INDIAN INSTITUTE OF TECHNOLOGY MANDIiitmandi.ac.in/workshops/SEFM/files/Abstract_Booklet.pdf ·...

INDIAN INSTITUTE OF TECHNOLOGY MANDI

SPECTROSCOPY OF EMERGING FUNCTIONAL MATERIALS,

Program Schedule for MONDAY 9th October, 2017

Time Venue

Speaker Session

Chair

8.30-9.00 am Recreation

centre

Breakfast

Registration (A1-NKN)

9.00 -9.10 am

A1 NKN

Welcome

9.10-9.25 am Inaugural Function

9.25- 10.05am Prof. Tonu Pullerits,

Lund University (Plenary lecture)

Dr. Prem

Felix

10.05-10.40 am Prof. Anunay Samanta,

University of Hyderabad (Invited)

10.40-11 am A1 Ground

Floor

TEA

11.00-11.30 am

A1 NKN

Prof. J. P. Singh, IIT Delhi (Invited) Dr. Ajay Soni

11.30-12.00 pm Dr. Pradeep Kumar, IIT Mandi

12.00-12.30 pm Dr Kamal P Singh, IISER Mohali (Invited)

12.30-12.40 pm Mr Pawan Kumar, IIT Mandi

12.40-12.50 pm Mr Abdus Salam Sarkar, IIT Mandi

1.00-2.00 pm Recreation

centre

Lunch

2.00-2.30 pm A1 NKN Dr. Sobhan Sen, JNU (Invited)

Dr Chandra

Shekhar

2.30-2.40 pm Mr Ashish Tiwary, IIT Mandi

2.40-2.50 pm Mr Saurabh Singh, IIT Mandi

2.50-4.00 pm Recreation

centre

Tea & Poster (P1-P15)

4.00-4.30 pm A1 NKN Dr. Khadga Jung Karki,

Lund University (Invited)

Dr Kaustav

Mukherjee

4.30-5.00 pm Dr Suman Kalyan Pal, IIT Mandi

5.00-5.30 pm Dr Abir De Sarkar, INST Mohali

5.30-6.00 pm Dr Ajay Soni, IIT Mandi

7.15 pm Recreation

centre

Dinner

http://chemistry.uohyd.ac.in/~as/

https://www.jnu.ac.in/content/sens

http://iitmandi.ac.in/workshops/SEFM/


SPECTROSCOPY OF EMERGING FUNCTIONAL MATERIALS,

Program Schedule for TUESDAY (10th October)

Time Venue

Speaker Session Chair

8.30-9.00 am Recreation

center

Breakfast

9.00 -9.40am

A1 NKN

Prof. K Gonsalves,

IIT Mandi (Invited)

Dr Subrata

Ghosh

9.40- 10.10am Dr. Arijit Kumar De,

IISER Mohali (Invited)

10.10-10.40 am Dr. Y Dwivedi,

NIT Kurukshetra (Invited)

10.40-11.40am A1 Ground

Floor

Tea/Poster (P-16 Onwards)

11.40-12.10 pm A1 NKN Dr. Rajiv Singh, NPL (Invited) Dr. Jaspreert

Kaur Randhawa 12.10-12.35pm Dr. Aditi Halder, IIT Mandi

12.35-12.55 pm Dr Bhupinder Singh, IIT Roorkee

12.55-1.05 pm Mr Mandeep Hooda, IIT Mandi

1.05-1.20 pm Vote of thanks/Prize distribution

1.30-2.2.15 pm Recreation

centre

Lunch

https://sites.google.com/site/akdegroupiisermohali/

http://www.nplindia.in/users/rajivsinghnplindiaorg

Invited Talks

I-1

From Light Absorption to Separated Charges: From Fundamentals

Towards Applications

Tonu Pullerits

Department of Chemical Physics, Lund University

Email: [email protected]

In this lecture I will give an overview of the studies of light harvesting materials in my

group during last few years. The topics covered include excitation dynamics in photosynthesis,

particularly the recently discussed aspect of coherence; photoinduced dynamics in colloidal

semiconductor quantum dots and their composites with metal oxides and graphene; excited state

and charge carrier properties in organometal halide perovskites. All materials are studied by using

a broad set of advanced laser spectroscopies.

I-2

Fluorescence Blinking, Photoactivation and Ultrafast Charge Carrier

Dynamics in All-Inorganic Perovskite Nanocrystals (CsPbX3)

Anunay Samanta

School of Chemistry, University of Hyderabad, Hyderabad 500 046, India


Organic-inorganic lead halide perovskite nanocrystals have received great attention in

recent years due to their potential applications in low cost efficient photovoltaic devices [1]. More

recently, cesium based all inorganic perovskite nanocrystals have also come into prominence in

several promising applications [2]. However, despite growing interests on all-inorganic perovskite

nanocrystals, fundamental photo-induced processes, whose understanding is key to exploitation of

these substances in potential applications, have remained largely unexplored. In this talk, photo-

inducd behavior of all-inorganic perovskite nanocrystals, CsPbBr3, CsPbBr2I and CsPbBr1.5I1.5

will be presented [3,4]. Specifically, fluorescence blinking and photoactivation of these

substances, as revealed by fluorescence correlation technique, and complete ultrafast charge carrier

dynamics, as measured by femtosecond time-resolved pump-probe technique, will be discussed.

References:

[1] Green, M.A.; Ho-Baillie, A.; Snaith, H.J. Nature Photonics 8 (2014) 506.

[2] Yakunin, S.; Protesescu, L.; Krieg, F.; Badnarchuk, M.I.; Nedelcu, G.; Humer, M.; Luca,

G.D.; Fiebig, M.; Heiss W.; Kovalenko, M.V. Nature Communications 6 (2015) 8056.

[3] Seth, S.; Mondal, N.; Patra, S.; Samanta, A. J. Phys. Chem. Lett. 7 (2016) 266.

[4] Mondal, N.; Samanta, A. Nanoscale 9 (2017)

I-3

Surface Enhanced Raman scattering for Rapid and Sensitive

Detection of Pathogens

J. P. Singh

Physics Department, Indian Institute of Technology Delhi, HauzKhas, New Delhi 110016


Surface enhanced Raman spectroscopy (SERS) has emerged as a promising technique for chemical

and biosensing applications as it combines molecular fingerprint specificity with potential single-molecule

sensitivity. Although SERS has emerged as a potential technique for chemical and biological sensing it has

few limitations like all the other techniques. Silicon wafers and glass slides are two of the most common

substrates used for the growth of SERS active layers. However, these substrates are rigid and brittle and

hence, limit some applications such as packaging or tracking where a flexible SERS substrate would be

more appropriate. Another limitation of these SERS substrates lies in a fact that they are mostly two-

dimensional (2D) planar systems. In 2D ordered substrates the number of hotspots is limited to only one

Cartesian x-y plane.Due to their one-time use, and considering the valuableness of the noble metals, these

SERS substrates cannot be completely explored as a routine analytical technique. Therefore, research has

been focused on developing reusable SERS-active substrates. A simple and elegant method to produce

highly uniform and arrays of nanostructures is glancing angle deposition (GLAD). This is a physical vapor

deposition process, which utilizes the self-shadowing effect that appears at highly oblique particle incidence

angles to create highly porous nanostructures. We have formed buckled AgNRs-PDMS SERS

substrates,which providebetter entrapment and increased contact area for P. aeruginosabacteria onto the

AgNRs giving rise to enhancement in the Raman signal. We have also demonstrated a simple and facile

method to fabricate a highly sensitive, flexible and robust SERS active substrate. The AgNRs arrays on

these flexible substrates retain their SERS activity after repeated cyclic tensile tests. As a proof of concept,

thiram pesticide with concentrations value 1000-fold lower than the level currently permissible in farming

has been detected on apple peels. Photocatalytic recyclable SERS substrates were fabricated by combining

plasmonic metal (Ag) with semiconductor TiO2. The Ag- TiO2 SERS substrates recovered after 150 min

in presence of UV light illumination. These revived substrates have shown to be successfully reused for

further SERS analyses with a correspondingly small decrease (on average 5% for each cycle) in the Raman

intensity. A simple method of chemical etching to create nanogaps in a zig-zag AgNR arrays which act as

SERS active hot spots for increased SERS detection sensitivity is also demonstrated. It was found that

SERS intensity increases with increase in the number of arm of zig-zag structure. The extremely high

electric field at the nanogap hot spots is responsible for enormous enhancement in SERS intensity.

References

1. A Rajput, S Kumar, JP Singh, Analytical Chemistry 10.1039/C7AN00851A (2107) 2 S Kumar, P Goel, JP Singh, Sensors and Actuators B: Chemical241, 577–583 (2017).

2. P Goel, S Kumar, J Sarkar, JP Singh, ACS applied materials & interfaces7, 8419-8426 (2015).

3. S Kumar, DK Lodhi, P Goel, P Mishra, JP Singh, Chemical Communications51, 12411-12414 (2015).

4. JP Singh, HY Chu, J Abell, RA Tripp, Y Zhao, Nanoscale4, 3410-3414 (2012).

I-4

Anomalous Phonons and Quasi-Particle Excitations in Iron-based

Superconductors

Pradeep Kumar

School of Basic Sciences, Indian Institute of Technology Mandi, Mandi-175005, Himachal

Pradesh India


Superconductivity, the resistance free flow of charge carriers, is one of the most exotic phenomena

in condensed matter physics. The phenomena of superconductivity, though discovered nearly a

century ago in 1911, still possess many fundamental questions, in particular the microscopic

pairing mechanism in high temperature superconductors. Discovery of superconductivity in Fe-

based systems by Kamihara et al., in 2008 breaks the monopoly of Cuprates as the only high

temperature superconductors. Their discovery is fundamentally important, in the sense that the

glue for the pairing mechanism may have magnetic origin; as well as raises many pertinent

questions like what is the role of magnetic degrees of freedom (DOF), electronic-nematicity and

it’s relation to underlying superconducting state, does superconductivity and magnetism truly

coexists, etc.

I will begin my talk with introducing this new class of iron-based superconductors (FeBS). Then

will discuss our temperature dependent Raman studies on different families of FeBS. Our studies

revealed the ubiquitous role of spin-phonon coupling in FeBS and coupled nature of spin and

orbital DOF, signalling the intricate role of these DOF in the pairing mechanism. Our studies

uncovered the non-degenerate nature Fe dxz/yz orbitals suggesting the electronic nematicity of

Fe3d-orbitals, which have very prominent role in determining their magnetic, electronic as well as

superconducting properties and are being debated hotly in FeBS.

I-5

The Processing and Heterostructuring of Silk with Light

Kamal P Singh

IISER Mohali


The spider silk is an excellent biomaterial that is light weight, elastic yet tougher than steel.

In this talk, I will discuss, how we can use few-cycle fs pulses to process silk in air with nanoscale

precision exploiting its non-linear multiphoton interaction with light. We shall also show our

attempts to weld silk with metal, Kevlar and polymers to combine their favourable properties. This

allows silk-based novel topological structures and devices such as radiation-pressure force sensors

capable of operating in air, on water surface and in high vacuum.

I-6

Quantifying Reaction Kinetics in Solution at Single Molecule Level

Sobhan Sen

School of Physical Sciences, Jawaharlal Nehru University, New Delhi

E-mail: [email protected]

Ensemble averaged experiments are widely used to study molecular diffusion and chemical

reactions. However, from such experiments it is rather difficult to follow how individual molecules

in solution interact with others at the single molecular level – so as to perform the overall

ensemble-averaged molecular processes. Recent developments of single molecular fluorescence

techniques have encouraged tremendous applicability to uncover intricate details of simple kinetic

steps of complex chemical and biochemical reactions in solution and inside biological cells/tissues.

Fluorescence correlation spectroscopy (FCS) is such a technique which allows monitoring and

quantifying molecular diffusion and chemical kinetics down at single molecule level. This talk

will focus on the application of FCS to monitor and quantify the molecular interactions such as

association and dissociation rates of a fluorescent ligand to DNA and growth kinetics of nanorods

inside microemulsion droplets in solution. This talk will showcase how FCS as a technique can be

efficiently used to study molecular diffusion and chemical kinetic reactions at single molecule

level.

I-7

Linear and nonlinear functional spectroscopy based on modulated

light fields

Khadga Jung Karki

Department of Chemical Physics, Lund University


A Recently, there has been a resurgence of spectroscopic methods based on modulated

light fields to investigate electronic structure and dynamics in various systems. One of the key

features of such methods is that one can isolate different kinds of linear and nonlinear signals in

the incoherent response, such as fluorescence and photocurrent, from the sample. This allows one

to directly probe the contribution of specific energy levels on the external "useful signal", thereby

providing in depth information about how electronic structure relates to the functionality. In this

tutorial talk, I will explain different kinds of spectroscopic methods based on modulated light fields

and types of information they provide.

I-8

Lifecycle of Photocarriers in Nanoscale Semiconductors

Suman Kalyan Pal

School of Basic Sciences and Advanced Materials Research Center, Indian Institute of

Technology Mandi, Kamand, Mandi-175005, Himachal Pradesh, India.


Semiconducting nanomaterials, quantum dots (QDs), and layered transition metal dichalcogenides

(TMDs) have shown promise for various optoelectronic applications including light emitting

diodes and solar cells. Understanding of basic mechanism of charge carrier generation and

knowledge about the lifecycle of the photocarriers in these materials are crucial to utilize them in

devices. In this talk, I will focus on photoinduced processes leading to charge carriers in few of

these excitonic materials. I will demonstrate hole transfer from ZnO to CdS QDs [1] following

Auger-assisted transfer mechanism (Figure 1) with the help of time-resolve emission spectroscopy.

Dissociation of excitons at the heterostructures of zero/two-dimensional (0D/2D) materials,

especially CdSe (cadmium selenide) QD/MoS2 (molybdenum disulfide) nanosheet via hole

transfer [2] will be shown. Femtosecond transient absorption measurements show the dissociation

of biexciton at the 0D/2D interface indicating that exploitation of ‘Multiple Exciton Generation’

effect is a feasible scenario. Migration of exciton from CdS as well as ZnS to CdSe site in segmented

CdSe@CdS/ZnS quantum rods will be addressed in this talk. Finally, some of our recent results of time-

resolved spectroscopic measurements on few-layer tin sulfide (SnS) and organo metal halide perovskites

(OMHPs) QDs will be presented.

Figure 1. Driving force vs rate constant plot. Filled squares are experimental data points.

References

[1] S. Ghosh, M. Ghosh, P. Kumar, A. S. Sarkar, S. K. Pal, J. Phys. Chem. C 2016, 120 (48),

27717-27723.

[2] A. Mushtaq, S. Ghosh, A. S. Sarkar, S. K. Pal, ACS Energy Lett. 2017, 2, 1879−1885.

400 600 800 1000

1E8

1E9

kH

T (

S-1

)

GHole (meV)

Auger-assisted

regime

Inverted

regime

Normal

regime

(a)

mailto:[email protected]

I-9

Ab initio study of nanomaterials for energy conversion and clean

environment

Abir De Sarkar

Institute of Nano Science and Technology, Phase - 10, Sector – 64, Mohali, Punjab-160 062

Email: [email protected], [email protected]

URL: https://sites.google.com/site/abirdesarkar/; http://www.inst.ac.in/faculty/Dr_Abir.html

Transition metal dichalcogenide (TMC) monolayers have been emerging as promising

alternatives to graphene on account of their intrinsic semiconducting band gap, which is a

prerequisite in electronics. Besides their intrinsic semiconducting properties, piezoelectric

properties arise in these monolayers owing to the broken inversion symmetry. MoS2 turns out to

be the most widely studied TMC. A synergic coupling between these two properties in single layer

MoS2 has been explored in our studies [J. Phys. Chem. C 121 (2017) 9181–9190] based on the

density functional theory for the optimization of nanoelectromechanical energy

conversion/harvesting and nanopiezotronic properties. MoS2 is also found to be interesting for 2D

thermoelectrics. The mechanism underlying the thermoelectric energy conversion in monolayer

MoS2 has also been investigated using density functional theory coupled to Boltzmann transport

equation [J. of Phys.: Cond. Matt. 29 (2017) 225501]. n-type doping is found to favorably enhance

the thermoelectric power factor in monolayer MoS2 nanosheet. Electronic properties and band gap

are found to be similarly sensitive to the application of mechanical strain. Both the electronic band

gap and the n-type Seebeck coefficient are found to reach their maxima, while the electron mobility

drops to its minimum at 3% compressive strain. Au catalysis for clean environment will then be

presented in my talk. Although Au is a noble metal in the bulk form, it shows high catalytic

activities at the nanoscale. The role of Aun (n=3-10) clusters in activating C2H2 molecules adsorbed

on it for further catalytic conversion of toxic HCN gas molecules into useful compounds such as

vinyl isocyanide, a versatile chemical intermediate, will also be covered in this talk [PCCP, 18

(2016) 13830-13843].

http://www.inst.ac.in/scientists_detail.php

I-10

EUV DUV and MUV wavelengths: from the past and present to the

future- from micro to nanofabrication and beyond

Keneth Gonsalves

School of Basic Sciences, IIT Mandi


This presentation will outline the trends in IC fabrication based on current and future trends

based on exposure wavelengths. The challenges of materials design and development will be

discussed and solution sought.

I-11

Dynamics of light harvesting: From ensemble measurements towards

single particle spectroscopy

Arijit K. De

Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER)

Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India.


In this talk, starting with a brief introduction on the discovery and importance of quantum

coherence in sunlight harvesting by natural systems, I will give a brief overview of ultrafast

energy/charge transfer within three quite different systems that is being pursued in our group: 1)

Bio-mimetic/Bio-inspired systems: Aggregates of xanthenes dyes, 2) Engineered systems:

Quantum dots and 3) Fluorescent proteins: GFP (WT) vs YFP (Venus)

If time permits, I’ll discuss how one can envisage the idea of spectroscopy of optically trapped

nanoparticles in solution by a femtosecond laser tweezer.

I-12

Fabrication and Application of Laser Scribed Photonic Structures

Y. Dwivedi

Department of Physics, National Institute of Technology, Kurukshetra


Saga of Laser and its advancement is full of up and downs. Over the recent years, the laser

technology and its potentials have been exciting laser manufacturers as well as researchers and

industrial users. Lasers with their un-parallel precision and beam quality assured advantages and

improvements in high precision and material processing at the micro-scale. Besides the excellent

beam quality there are more advantages of the laser technology such as compact installation size,

high laser efficiency, moderate system price and easy to be integrated. Lasers are not only used as

a characterization tool but also can also be used as mechanical tool to manipulate the variety of

structures down to size micro and submicro meter. Laser structuring or Laser micromachining is a

general term that includes a variety of processes including hole drilling, ablation, milling, and

cutting. Lasers offer a wide range of wavelengths, pulse duration (from femtosecond to

microsecond) and repetition rates (from single pulse to Megahertz). These attributes allow

micromachining with high resolution in depth and lateral dimensions. Laser micromachining

techniques are currently used by the automobile and medical industries as well as in the production

of semiconductors and solar cell processing. The field of micro-machining includes manufacturing

methods like drilling, cutting, welding as well as ablation and material surface texturing, whereby

it is possible to achieve very fine surface structures ranging in the micrometer domain. Such

processes require a rapid heating, melting and evaporation of the material. The use of extremely

short nano- and pico- and even femtosecond pulse durations helps to minimize the thermal effects

such as melting and burr formation thus eliminating the need for any post processing measures. In

this lecture, in addition to the detailed discussion on laser micromachining and photolithography,

I will describe the application of femtosecond laser to writing different structures including

photonic structures like Grating, high quality fibers, lenses etc. and micro mechanical sensors for

car security systems, nozzle plates for printer, and optical elements for X-ray beam splitting.

Wherever the accuracy of etched silicon structures is not required, laser processes with short pulses

and small wave length can be an option with the advantage of shorter process time. A special

emphasis will be to describe waveguide (down to ~2 micrometer diameter) and volume grating

fabrication by a 1 MHz femtosecond Ti:Al2O3 laser in barium borate glasses and discuss its

structural and optical properties in detail. Waveguides fabricated are characterized by diffraction

and Raman analysis. Raman analysis indicates structural modification on fs laser irradiance.

Glasses doped with Pr and Eu show good emissive characteristics on excitation with UV/blue

radiations, spanning in the wide spectral range. Different emission pattern were obtained with

selective excitations in charge transfer band, 4f-5d band and 4f-4f band of Pr ion. Observed

properties will also be discussed in detail using absorption, excitation and lifetime analysis.

I-13

Charge Carrier Dynamics and Interfacial Interaction Study in

Organic Solar Cell

Rajiv Singh

National Physical Laboratory, K. S. Krishnan Marg, New Delhi


The carrier dynamics been investigated by ultrafast fast absorption spectroscopy in organic

solar cell materials has leads insight view of various energy states in molecules and its decay

dynamics. The effect of surface plasmons of nanoparticles and charge species can also be identified

specifically with respect to their energy levels appearing in ultrafast time domain. Improvement in

recombination resistance at the various interfaces can be demonstrated by impedance spectroscopy

study. These studies can cumulative map the progress in efficient internal charge transfer and

reduction in recombination mechanism in organic materials for energy harvesting.

I-14

Role of Spectroscopy In the area of Non-Platinum Group

Fuel Cell Catalysts

Aditi Halder

School of Basic Science, Indian Institute of Technology, Mandi

Nitrogen doped carbon supported iron (Fe-N-C) framework has gained tremendous attention as

an excellent alternative of platinum for catalysis of oxygen reduction reaction (ORR) of proton

exchange membrane fuel cell (PEMFC). Spectroscopy is a useful technique for evaluating the

different functionalities arisen into the final catalysts materials after the chemical and thermal

treatment of precursor molecules while synthesizing the catalyst. The influence of various nitrogen

groups and metal precursors on the properties of electrocatalysts can only be evaluated with the

help of different spectroscopic techniques like X-ray diffraction and X-ray photoelectron

Spectroscopy. Electrochemical studies including hydrodynamic rotating ring disk electrode

measurement along with the various spectroscopic measurement, reveals the exact mechanism

followed in the catalytic process.

Contributory Talks

O-1

Atomically sharp edges and faceted voids in CVD grown WS2

monolayers

Pawan Kumara and B. Viswanathb

School of Engineering, Indian Institute of Technology Mandi, Kamand, India-175005 [email protected], [email protected]

Research on 2-dimensional (2D) materials explored as a paradigm shift in the field of

nanoscale material with the discovery of graphene like other nano-sheets such as transition metal

dichalcogenides (TMDCs: MoS2, WS2, MoSe2, etc.) due to their superior properties with reduced

layer thicknesses. Monolayer MoS2 and WS2 provide better performance of photoluminescence

with structural stability at ambient condition among the group of TMDCs. Two dimensional

flatland having enormously larger active surfaces and atomic terminated edges are undergoing

considerable interest owing to many interesting phenomena and processes when it interact with

ambiguous environment. We have grown large single crystalline, atomically thin monolayers of

WS2 in atmospheric pressure CVD system and investigated their intriguing behavior with various

spectroscopic as well as microscopic techniques. Time dependent dynamic as well as static void

evolution in atomically thin monolayers provide the structural rearrangement in hexagonal WS2.

Photoluminescence and Raman spectral analysis have been carried out to investigate the

atomically terminated edges behavior as well as flatland surface properties. The ability to

manipulate edges and voids in atomic monolayers provide new opportunities to control the

properties locally towards various optoelectronics and nanoelectronics applications.

References:

1. Mak, K. F.; Lee, C.; Hone, J.; Shan, J.; Heinz, T. F. Atomically thin MoS 2: a new direct-gap

semiconductor. Physical review letters 2010, 105, 136805.

2. Ye, G.; Gong, Y.; Lin, J.; Li, B.; He, Y.; Pantelides, S. T.; Zhou, W.; Vajtai, R.; Ajayan, P. M. Defects

Engineered Monolayer MoS2 for Improved Hydrogen Evolution Reaction. Nano Lett 2016, 16, 1097-103.

3. Gutierrez, H. R.; Perea-Lopez, N.; Elias, A. L.; Berkdemir, A.; Wang, B.; Lv, R.; Lopez-Urias, F.;

Crespi, V. H.; Terrones, H.; Terrones, M. Extraordinary room-temperature photoluminescence in

triangular WS2 monolayers. Nano Lett 2013, 13, 3447-54.

4. Hou, J.; Wang, X.; Fu, D.; Ko, C.; Chen, Y.; Sun, Y.; Lee, S.; Wang, K. X.; Dong, K.; Sun, Y.;

Tongay, S.; Jiao, L.; Yao, J.; Liu, K.; Wu, J. Modulating Photoluminescence of Monolayer Molybdenum

Disulfide by Metal–Insulator Phase Transition in Active Substrates. Small 2016, 12, 3976-3984.

O-2

Photophysical Properties of Emerging Two-Dimensional Materials

and Their van der Waals Heterostructures

Abdus Salam Sarkar and Suman Kalyan Pal


Technology Mandi, Kamand, Mandi-175005, Himachal Pradesh, India.

Email: [email protected], [email protected]

Heterostructures of layered two-dimensional (2D) transition metal dichalcogenides

(TMDs) and organic semiconductors have emerged as promising candidates for next generation

electronics and optoelectronics. [1, 2] However, the development of advanced materials and detail

investigation of light-mater interactions are required to exploit them in real electronic

applications. In this talk, I will present a fully solution processable method (Figure 1) called

semiconductive polymer assisted chemical exfoliation (SPACE) of exfoliating layered

molybdenum disulfide (MoS2) forming polymer-MoS2 nanoheterojunctions. Efficient

dissociation of excitons in these heterostrojunctions will be demonstrated and explained.

Synthesized nanoheterojunctions show both photovoltaic and bipolar resistive switching effect.

[3] Temperature dependent Raman spectroscopic investigation has been undertaken to know

about the electron-phonon (e-p) interaction in these heterojunctions. [4] Furthermore, synthesis

and Raman spectroscopic studies of large area ultrathin (few-layer) tin(II) sulfide (SnS) will be

presented.

Figure 1. Schematic of SPACE method and atomic force microscopic image of ultrathin SnS

sheet.

References

1. K. F. Mak and J. Shan, Nat. Photon., 2016, 10, 216-226.

2. D. Jariwala, T.J. Marks and M. C. Hersam, Nat. Mater. 2017, 16,170-181.

3. A. S. Sarkar and S. K. Pal, J. Phys. Chem. C., 2017, DOI: 10.1021/acs.jpcc.7b07132.

4. A. S. Sarkar and S. K. Pal, ACS Omega, 2017, 2, 4333-4340.


O-3

Multifunctional magnetic and fluorescent hybrid core shell NPs

containing exceedingly small iron oxide nanocrystals for multimodal

imaging and biosensing Ashish Tiwari and Jaspreet Kaur Randhawa*

School of Engineering, Indian Institute of Technology Mandi, Himachal Pradesh, India


The present study involves fabrication of biocompatible multifunctional magnetic and fluorescent

hybrid core shell nanoparticles (MFCSNPs) in single step synthesis method. Magnetic core of MFCSNPs

is iron oxide (Fe3O4) providing superparamagnetic properties which can be exploited for magnetic

resonance imaging (MRI) in cancer diagnostics. Fluorescent shell is carbon coating which enable optical

properties in MFCSNPs; saturated with carbonyl and hydroxyl groups making them advantageous for

bioimaging in cancer detection and therapy. Multiple surface functionalities of MFCSNPs offer a choice to

feat them as a drug carrier with efficient drug loading and targeting ability. Structural and morphological

features showed spherical core shell NPs with an average particle size of 230 nm containing small iron

oxide nanocrystals with an average size of 8 nm. Successful carbon coating on iron oxide nanocrystals was

confirmed by STEM images and elemental mapping. MFCSNPs showed superior superparamagnetic

behaviour with minimum coercivity and saturation magnetization of 29.34 emu/gm. CLSM imaging

displayed multicolour fluorescence spectra with tunable excitation wavelength. Achieving strong

fluorescence, superparamagnetic behaviour and good biocompatibility, MFCSNPs can be internalized into

the cells following accumulation in cell cytoplasm, which parade desirable capability for bioimaging in

therapeutic application. Moreover, systemic investigation of in vitro molecular interactions between

MFCSNPs with bovine serum albumin (BSA) were elucidated appropriately. The microenvironmental and

conformational changes of BSA induced by MFCSNPs were investigated by multi spectroscopic methods.

These results suggested that conformational change of BSA was significantly at secondary structure level

and biological activity of BSA was weakened dramatically in the presence of MFCSNPs.

Figure 1. TEM, PL and VSM spectra of MFCSNPs and PL and CD spectra of interaction with BSA.

References 1. Xiao, Lisong, et al. "Water-soluble superparamagnetic magnetite nanoparticles with biocompatible

coating for enhanced magnetic resonance imaging." ACS Nano 5.8 (2011): 6315-6324.

2. Wei, He, et al. "Exceedingly small iron oxide nanoparticles as positive MRI contrast agents." Proceedings

of the National Academy of Sciences (2017): 201620145.

O-4

Experimental and Theoretical Study of Oxide Materials for

Thermoelectric Applications

S. Singh, S. K. Pandey

School of Engineering, Indian Institute of Technology Mandi, Kamand, H.P.-175005 India. Email: [email protected]

In the past few decades, research in the field of thermoelectric (TE) materials have attracted

much attention for an alternate source of energy. For high temperature TE materials, an

investigation of oxides materials have more advantageous due to its nontoxic character, availability

in nature, structural and chemical stabilities, oxidation resistant properties over the conventional

TE materials (Be-Te, Pb-Te based alloys). Therefore, TE properties of oxide materials have been

explored by using experimental tool and electronic structure calculations (DFT+U).[1]

Measurement of α was carried out for the ZnV2O4, LaCoO3, La0.82Ba0.18CoO3, and

La0.75Ba0.25CoO3 compounds in 300-600 K range. [2-6] Experimental data of these compounds in

230-600 K temperature range have been explained successfully from the effective mass and

transport coefficient calculations. The consideration of temperature dependent energy gap is found

to be more effective in understanding the behaviour of α in ZnV2O4 and LaCoO3 compounds [4].

Also, the dependency of chemical potential on effective mass of charge carriers through

temperature plays a crucial role in the study of TE behaviour of both the compounds. The electronic

structure calculations shows the half-metallic character for La0.82Ba0.18CoO3 and La0.75Ba0.25CoO3

compound. In both the compound, consideration of temperature dependent relaxation time of up

and down-spin channel gives a reasonably good matching between experimental and calculated

values of α in 300-600 K. For La0.82Ba0.18CoO3, electrical resistivity measurement was also carried

out in 300-600 K range. DFT+U method was used to estimate the values of σ/τ, where the

temperature dependent values of relaxation time (τ), almost linear for up-spin (τup) and non-linear

for dn-spin (τdn), were used in two current model and estimated values were found to be in good

agreement with experimentally data in the entire temperature range [6]. Theoretically calculated

values of ZT for p-type doped ZnV2O4 (in 900-1400 K) and n-type doped LaCoO3 (in 600-1100

K) are found to be ~0.3 and ~0.35, respectively [2,3]. These values of ZT are nearly one third of

the well know thermoelectric oxide NaxCoO2 (ZT ~1 in 700-1000 K), this suggest that doped

LaCoO3 and ZnV2O4 compound can be good materials for the thermoelectric applications in

thermal power plant, spacecraft exhaust, armored vehicles exhaust, steel industry, etc.

References:

1) S. Singh and S. K. Pandey, Measurement, 102, 26-32 (2017).

2) S. Singh, R. K. Maurya, and S. K. Pandey, J. Phys. D: Appl. Phys., 49, 425601-10 (2016).

3) S. Singh and S. K. Pandey, Philosophical Magazine, 97:6, 451-463 (2017).

4) S. Singh and S. K. Pandey, Mater. Res. Express, 3, 105501-7 (2016).

5) S. Singh, D. Kumar and S. K. Pandey, J. Phys.: Condens. Matter, 29, 105601-7 (2017).

6) S. Singh, D. Kumar and S. K. Pandey, Phys. Lett. A 381, 3101 (2017).

O-5

ICPMS: A VERSATILE TOOL

Bhupender Singh

Institute Instrumentation Centre, I.I.T. Roorkee, Roorkee-247667


Impurities at trace or ultra-trace level (ppm, ppb, ppt) significantly affect the physico-chemical

properties, efficiency and usability of the materials. In order to fabricate advanced functional

materials we need to monitor the elemental composition at the various stage. Inductively coupled

plasma–mass spectrometry (ICPMS) is the fastest and the sensitive tool multi-elemental analytical

technique to check the purity of the material. ICPMS technique have been widely used in area of

life sciences, environmental sciences, food sciences, health science, earth sciences, forensics,

material science, metallurgy, archaeological and other industrial applications. Advanced

hyphenated techniques have widened the scope of this technique

O-6

Enhanced Thermopower and low thermal conductivity in p-type

polycrystalline ZrTe5

M. K. Hooda and C. S. Yadav

School of Basic Sciences, Indian Institute of Technology Mandi, Mandi-175005 (H.P.) India


ZrTe5 is the well studied transition metal pentatelluride material due to its resistivity

anomaly in the temperature range 60 to 150 K and large thermoelectric power (S) which shows

electron dominance (negative S) below the anomaly temperature and above it hole dominance

(positive S) [1-2]. Recently another form of ZrTe5 (p-type) was discovered which shows hole

dominated S in the whole temperature range (2-340K) and semiconducting behavior [3-5]. We

have explored the thermoelectric properties of polycrystalline p-type ZrTe5 in temperature (T)

range 2 - 340 K. Thermoelectric power (S) is positive and reaches up to 458 V/K at 340 K on

increasing T. The value of Fermi energy 16 meV, suggests low carrier density of 9.5 1018 cm-

3. A sharp anomaly in S data is observed at 38 K, which seems intrinsic to p-type ZrTe5. The

thermal conductivity () value is low (2 W/m-K at T = 300 K) with major contribution from lattice

part. Electrical resistivity data shows metal to semiconductor transition at T ~150 K and non-

Arrhenius behavior in the semiconducting region. The figure of merit zT (0.026 at T = 300 K) is

~63% higher than HfTe5 (0.016), and better than the conventional SnTe, p-type PbTe and bipolar

pristine ZrTe5 compounds.

References:

[1] S. Furuseth, L. Brattas, and A. Kjekshus, Acta Chem. Scand. 27, 2357 (1973).

[2] H. Fjellavg and A. Kjekshus, Solid State Comm. 60, 91 (1986).

[3] A. Pariari and P. Mandal, Nature Scientific Reports 7, 40327 (2017).

[4] P. Shahi et al., arxiv:1611.06370 (2016).

[5] M. K. Hooda and C. S. Yadav, Appl. Phys. Lett. 111, 053902 (2017).

Poster Presentation

P-1

Analytical challenges in drug analysis and its impact and solution in

daily life

Ankur Kumar and Dr. Manjeet Agarwal

National Institute of Food Technology Entrepreneurship and Management

(Under Ministry of Food Processing Industries, Government of India), Haryana-131028


Drug discovery is a commonly known area of Research and Development. Today, The

pharmaceutical industries and The Research organization are facing a lots of challenges like-non

compliance of Food and Drug Administration(FDA) standard because of non-conformity of

analytical result, violation of good laboratory practice(GLP) and good manufacturing

practice(GMP) norms .Analytical data represents the final report of a product before going into the

markets. Analytical problem can be resolved by selecting correct route of synthesis from the

beginning, correct specification, by following correct methodology for the analysis with validated

analytical methods as per International conference on harmonization (ICH), which is

internationally recognized, correct reporting of analytical result with respect to the standard

specification value. Investigation of out of trend results (OOT) and out of specification results

(OOS) and the systematic reporting of deviations with proper justification and corrective and

preventive actions (CAPA).

Key words- Analytical challenges, Drug analysis, FDA, GMP, GLP and ICH.

P-2

Electron Beam Lithography of sensitive resist based on photoacid

generator integrated terpolymer: potentiality of high-resolution

pattern transfer Santu Nandi1, Midathala Yogesh1, Pulikanti Guruprasad Reddy1, Satinder K. Sharma2,

Chullikkattil P. Pradeep1, Subrata Ghosh1* and Kenneth E. Gonsalves1*

1School of Basic Sciences, Indian Institute of Technology Mandi, H.P. 175005, India. 2 School Computing and Electrical Engineering, Indian Institute of Technology Mandi, H.P.

175005, India. *e-mail: [email protected], [email protected]

Nanolithography technology has been extensively used in semiconductor fabrication process to

manufacture micro/nano electronics. Photolithography has been recognized to be the fundamental

technology in IC manufacture for a very long time because it has a significant role to define a number of

discrete devices per integrated circuit. Now a days developing new photoresist materials for different

lithography applications, starting from high to low nodes, the potential of the resist in successful

pattern transfer has been the key role in semiconductor industries. The current semiconductor

industries are looking sub-10 nm features for potential manufacture of sophisticated nano-

electronics, however, the materials with lower node features particularly at sub-100 nm regime is

also equally important for current IC industries especially in the CMOS technology. Considering

these, we have designed and synthesized a new terpolymer viz. GBLMA-MAMA-MAPDST

photoresists for the electron beam lithography (EBL) applications. EBL studies reveal that the

synthesized terpolymer resist (GBLMA-MAMA-MAPDST) is sensitive to the radiations and able

to show 100 nm (L/S) and 70 nm isolated positive tone line features after TMAH development. The

sensitivity (E0) and contrast (γ) of this resist were calculated from the contrast curve analysis as

36.5µC/cm2 and 0.08 respectively. At last, the potential to transfer positive higher resolution nano

features on the silicon substrate has been achieved by suitable dry plasma etching technique.

Fig. 1. (a) Structure of Terpolymer, (b) EBL pattern of 100 nm L/S, (c) AFM image of

transferred pattern onto Silicon.

References:

1. S. Ghosh, C. P. Pradeep, S. K. Sharma, P. G. Reddy, S. P. Pal and K. E. Gonsalves, RSC Adv. 2016,

6, 74462.

2. K. E. Gonsalves, M. Wang, C. T. Lee, W. Yueh, M. T. Tapia, N. Batinad and C. L. Henderson, J.

Mater. Chem. 2009, 19, 2797.

P-3

Emission enhancement and color tuning for Lanthanide activated

Bi2SiO5 nanophosphor

Pushpa Kumari, and Y. Dwivedi

Department of Physics, National Institute of Technology Kurukshetra, Kurukshetra, Haryana –

136119 India

Email:[email protected]

A series of Dy3+ and Tb3+ ions doped and co-doped Bi2SiO5 nanophosphors were

synthesized by hydrothermal, combustion and co-precipitation methods. Bi3+ ions are very good

sensitizers of luminescence, which can absorb the UV light and transfer this energy to the

activator center. Various structural characterizations were made using X-ray diffraction,

Scanning electron microscopy, transmission electron microscopy etc. Bi2SiO5 crystalline phase

analysis was confirmed by X-ray diffraction technique of size ~25 nm and no any significant

change in phase and size with doping. We have explored the various vibrational and optical

properties including FTIR, Raman, absorption, photoexcitation and emission of synthesized

samples. Dy3+ ions activated Bi2SiO5 nanophosphor yields yellowish white light, which

perception change with Tb3+ ions. The energy transfer phenomenon between Dy3+ and Tb3+ ions

was validated in Dy3+/Tb3+ co-doped Bi2SiO5 nanophosphor and confirming the fact that the

dipole–dipole interaction is responsible for the energy transfer process of Dy3+→ Tb3+ from 4F9/2→ 6H15/2 level. Spectroscopic characterizations of these energy transferred were explore by

time resolved spectroscopy. Detail photophysics of the materials were explored and will be

discuss during the presentation.

Acknowledgment:

I would like to acknowledge the financial support from fellowship HSCST/2015/1, Haryana State

Council for Science & Technology.

P-4

Development of ZnO/ Polyaniline core-shell nanostructure for room

temperature LPG Sensing

Lalit Kumar, Divyanshu Katiyar, Randheer Gautam

Department of Physics, Hindu College, University of Delhi, Delhi-10007.


Nanomaterials display great promise in the development of science and technology due to

their concomitant properties and interesting behaviour compared to their bulk counterparts.

Inorganic/organic hybrid semiconductor devices are being explored for their potential of added

electronic versatility by combining two contrasting but well-developed materials for novel

applications. In this work, hybrid inorganic-organic nanomaterial is investigated for gas sensing

property, with zinc oxide (ZnO) as inorganic part and polyaniline (PANI) as organic component.

We employed in-situ polymerization technique to synthesize ZnO/PANI core-shell structure. The

XRD pattern of core shell structure exhibited peaks corresponding to pure ZnO, indicating the

presence of pure ZnO in the core, which is further corroborated by SEM microscopy. We

investigated the LPG sensing property of ZnO/PANI core shell and found room temperature

response and recovery behaviour. Maximum sensitivity was achieved at 35 °C, indicating

suitability of ZnO/PANI core shell towards LPG sensing as compared to pure ZnO and PANI.

Figure: XRD pattern of pure ZnO, pure PANI and ZnO/PANI core-shell nanostructure

and TEM image of core-shell .

P-5

Fabrication of γ-MnS and γ-MnS/ S and N co-doped three-

dimensional graphene composite for electrochemical properties as an

electrode material for supercapacitors

Sushil Kumar, Khushboo Soni, Sk. Riyajuddin, Shivang Bajaj, Sabyasachi Karmakar and

Kaushik Ghosh*

Institute of Nano Science & Technology, Habitat Centre, Phase-10, Sector-64, Mohali- 160062


With the rising fossil fuel prices and the increasing environmental problems resulting from burning

fossil fuels, global community is looking for environment-friendly energy resources, which require to be

sustainable and renewable. Electrochemical energy generation and storage devices, such as supercapacitor

for high energy storage due to its attractive advantages in terms of high power density, long cycle life, low

maintenance cost, simplicity and better safety compared with secondary batteries such as Li-ion or Lead

Acid batteries. MnS has three different polymorphs: the green stable rock salt structure (α-MnS), the pink

metastable zinc blende structure (β-MnS), and the wurtzite structure (γ-MnS). Till now, various shapes of

MnS nanoand microcrystals have been achieved by a hydrothermal, solvo-thermal, thermolysis, and spray-

produced process. Generally, the synthesis of metastable phase γ -MnS is still a challenging and intriguing

task. For electrode active materials, a graphene coating is an efficient way to enhance conductivity. If

nanostructured graphene is used as the matrix for γ -MnS based composites, it cannot only well

accommodate the γ-MnS particles, but also offer a smooth electrode/electrolyte interface for the charge-

transfer reaction. Here we demonstrate the effect of γ -MnS /graphene-based composite material for solid-

state-supercapacitors. γ -MnS and γ- MnS/S,N-3DG composite was successfully fabricated via a facile one-

pot solvothermal route. The γ- MnS hollow spheres consisting of γ- MnS nanoparticles or γ- MnS rods with

hierarchical architectures which create a facile interface via S and N codoped graphene with 3D graphene

electrodes.

Fig1:(a) Cyclic Voltametric analysis of γ- MnS from scan rate (10-100 mV/s), (b) SEM analysis

γ- MnS and insert γ- MnS/S,N-3D graphene composite.

γ-

S,N-

(a) (b)

P-6

Functionalization of Graphene Oxide Dispersions for Conductive

Inks and Supercapacitor Applications Mahesh Soni, 1 Ajay Soni,2 Satinder Kumar Sharma1

1School of Computing and Electrical Engineering, Indian Institute of Technology Mandi-175005,

HP, India

2School of Basic Sciences, Indian Institute of Technology, Mandi-175005, HP, India


Recently, 2D layered materials such as graphene, derivatives graphene oxide (GO) and

reduced graphene oxide (rGO) have absorbed significant attention to explore novel functionalities

for technological applications like nano-electronics, photovoltaics, conductive inks, interconnects

and supercapacitors [1]. The interest towards GO/rGO is due to excellent electronic, optical,

mechanical properties, high surface to volume ratio and atomically thin dispersion in water [2].

Moreover, the electrical conductivity of the insulating GO can be tuned by reduction, rGO. The

rGO obtained via reduction of aqueous GO tends to agglomerate with time and hinders the

commercial scale applications for conductive inks and high-density energy storage. To address the

challenge, we will demonstrate a low-cost approach for large-scale production of rGO via photo-

catalytic functionalization of GO under UV illumination (λ ~ 253 nm) in presence of N-Methyl-

2-Pyrrolidone (NMP). The obtained rGO retains the long-term stable homogenous dispersion for

more than 160 days with 2D morphologies. The high stability of dispersion and electrochemical

performance of synthesized rGO is envisaged for potential applications in high density energy

storage and conductive inks for flexible electronics [3].

References

[1] X. Huang, Z. Yin, S. Wu, X. Qi, Q. He, Q. Zhang, et al., "Graphene‐based materials: synthesis, characterization,

properties, and applications," small, vol. 7, pp. 1876-1902, 2011.

[2] D. R. Dreyer, S. Park, C. W. Bielawski, and R. S. Ruoff, "The chemistry of graphene oxide," Chem Soc Rev, vol.

39, pp. 228-40, Jan 2010.

[3] M. Soni, P. Kumar, R. Kumar, S. K. Sharma, and A. Soni, "Photo-catalytic reduction of oxygenated graphene

dispersions for supercapacitor applications," Journal of Physics D: Applied Physics, vol. 50, 2017.

P-7

Band Modification and Soft Phonon Modes in Transition Metal and

Rare-Earth Element Doped SnTe

Somnath Acharya, Juhi Pandey and Ajay Soni*

School of Basic Sciences, Indian Institute of Technology Mandi, Mandi, Himachal Pradesh

175005, India

*Email: [email protected]

The advancements on thermoelectric materials research are associated with band

engineering and phonon engineering, which can modify the electronic band structure and phonon

transport.[1, 2] In past few years, tin telluride (SnTe) based alloys are regarded as promising

thermoelectric material analogous to lead chalcogenides due to identical crystal structure and

complex band structure. The optimization of carrier concentration is a major challenge for SnTe

which can be achieved by self-compensation of Sn and doping at inherent Sn sites.[3, 4] The

presentation will discuss on the results of thermoelectric performance of transition metal and rare

earth element doped SnTe. The enhancement in thermopower has been explained with electronic

band modification and poor thermal conductivity is understood based on point defect scattering

and appearance of impurity driven soft phonon mode.[5, 6] The appearance of the soft phonon

modes and blue shift in Raman spectra of Mn doped samples justifies the role of Mn for breaking

center of inversion symmetry and acting as point defect scattering center for the major part of

broad spectrum of phonon frequencies.

References

[1] Y. Pei, H. Wang, and G. J. Snyder, Advanced Materials 24 (2012) 6125.

[2] W. Kim, Journal of Materials Chemistry C 3 (2015) 10336.

[3] R. F. Brebrick and A. J. Strauss, Physical Review 131 (1963) 104.

[4] G. Tan, L.-D. Zhao, F. Shi, J. W. Doak, S.-H. Lo, H. Sun, C. Wolverton, V. P. Dravid, C.

Uher, and M. G. Kanatzidis, Journal of the American Chemical Society 136 (2014) 7006.

[5] S. Acharya, J. Pandey, and A. Soni, Applied Physics Letters 109 (2016) 133904.

[6] S. Acharya and A. Soni, AIP Conference Proceedings 1832 (2017) 110028.

P-8

Highly luminous white light emission from organic dyes in a binary

system for WLED

Rashmi, Y.Dwivedi*

Department of Physics, National Institute of Technology Kurukshetra – 136119, Haryana


Present works discuss spectroscopic investigations of organic laser dyes (C102, and Rh6G)

in mono and binary system in different polar environments namely (ethanol, acetone,

dimethylformamide, water, and cyclohexane). In the binary system energy transfer (ET) was

observed from C102 (donor) to Rh6G (acceptor) dye which was utilized in such a way to tune

white light. By properly tuning the mixing ratio of both the laser dyes (in ethanolic solution) to

achieve efficient energy transfer in order to balance the red and blue spectral emission contribution

of the binary system, a fairly pure and stable white light has been obtained with CIE-1931

chromaticity coordinates of (0.35, 0.33).

We have explored the various vibrational and optical properties including FTIR, UV-

Visible absorption, Photo-excitation and photoluminescence of samples. When compared, photo-

excitation and photoluminescence spectra (PLE and PL) of C102, Rh6G and binary system dye

shows different behavior like, variation in peak profile, FWHM, Stoke’s shift, and red-shift were

observed with the increase of the solvent polarity. The energy transfer and several related

parameters in the dyes were investigated and analyzed implementing time-resolved fluorescence

spectroscopy. Also, the thermal stability of the dyes was also investigated and a simple structure

which avoids color degradation is proposed. We have estimated various radiative parameters like

quantum efficiency, absorption and emission cross-section etc. Detail of the other result will be

discussed during presentation.

Reference

[1] K. Singh and G. C. Joshi, “Influence of donor-donor transport on excitation energy transfer

in binary system C343-Rh6G doped in Poly(methylmethacrylate),” IOSR J. Appl. Phys.,

vol. 7, no. 6, pp. 3–13, 2015.

P-9

Dynamics of different emissive states in CH3NH3PbBr3 perovskite

Supriya Ghosh,1 Suman Kalyan Pal,1 * Khadga jung Karki2*and Tonu Pullerits2*

1School of Basic Sciences, Indian Institute of Technology Mandi, H.P. 175005, India. 2 Department of Chemical Physics and NanoLund, Lund University, Lund, Sweden.

*Email: [email protected]

Organo metal halide perovskites (OMHPs) seem to have the potential to challenge

traditional silicon technology.1 Therefore, the understanding of the fundamental light-induced

processes in OMHPs from charge-photo generation, migration of charge carries2 through the

materials and finally their recombination is very important. We investigate the local changes in

photophysics at different micro-regions of a methyl-ammonium lead bromide (MAPbBr3)

perovskite crystal under illumination. The yield and spectrum of the emission from the structurally

homogeneous region does not vary with the illumination time, whereas inhomogeneous region

shown a distinct light induced changes in the spectra.3 Our results indicate that the bimolecular

band to band recombination is the main emission source for the homogenous region on the other

hand emission from the inhomogeneous regions is due to the defects. At long illumination time,

photo induced ion-migration passivate the defect centre and consequently inhibits the defects

related emission, thereby decreasing their contribution to the emission. The measurements of the

emission lifetime show that the kinetics is dominated by the defect related emission at short

illumination times and the band edge emission at the longer illumination times. Our work provides

a direct evidence for the light induced healing of the defect centers, which is important in the

design of photoactive devices of MAPbBr3.

Fig. 1. (a) Change of integrated PL with illumination time at homogeneous region (blue) and

inhomogeneous region (orange). (b) Illustration of defect passivation with illumination time.

References:

[1] S. D. Stranks, H. J. .Snaith, Nat. Nanotechnol. 2015, 10, 391-402.

[2] E. Mosconi, D. Meggiolaro, H. J. Snaith, S. D. Stranks, F. De Angelis, Energy Environ. Sci.

2016, 9, 3180-3187.

[3] S. Ghosh, S. K Pal, K. J. Karki, T. Pullerits S, ACS Energy lett. 2017, 2, 2133-2139.

0 10 20 30 40 50 60 70 80

105

106

Inte

gra

ted

PL

(a.

u.)

Illumination time (min)

(d)

δ+

e-

h+

e-

e-

h+

hνhν

Br-

2 ns

δ+

2 ns

Strongly emittingtrapping sites

Healing of the trappingsites due to halide ionmigration

Under lightillumination over time

(a) (b)

P-10

Enhancement of Luminescence Intensity in Red Emitting

NaYF4:Yb/Ho/Mn Upconversion Nanophosphors by Variation of

Reaction Parameters

K. Lingeshwar Reddy,a Vaddepally Srinivas,a Konathala Ravi Shankar,a,c Suneel Kumar,a Vipul

Sharma,a Ajay Kumar,a Ashish Bahuguna,a Kaustava Bhattacharyya,b and Venkata Krishnan*a aSchool of Basic Sciences and Advanced Materials Research Center, Indian Institute of Technology Mandi,

Kamand, Mandi, Himachal Pradesh, 175005, India. bChemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra, India. cCurrent address: School of Nano Sciences, Central University of Gujarat, Gandhinagar 382030, India

*E-mail: [email protected]

In the field of biomedicine, upconversion nanoparticles have wide ranging applications from

bioimaging to targeted cargo delivery, especially due to their excellent chemical and optical properties in

comparison to conventional fluorophores. However, their use in biomedical applications is largely hindered

due to strong absorption of short wavelength (< 600 nm) light by biological tissues/cells and feeble

luminescence. Hence, it is important to develop new strategies to increase the long wavelength (red)

emission efficiency. In this work, we report an effective strategy to improve the red luminescence efficiency

of NaYF4:Yb/Ho/Mn upconversion nanophosphors by varying the reaction conditions. The influence of

different synthesis parameters, such as solvent ratio, reaction temperature and reaction time, on the

luminescence, crystal phase and morphology of the upconversion nanophosphors has been studied in detail

and optimized. The improvement in the crystallinity of nanophosphors is claimed as the main origin for the

increase in the red emission intensity. This work could pave way for the versatile use of these bright red

emitting upconversion nanophosphors in biomedical applications.

Key words: Upconversion nanophosphors; NaYF4:Yb/Ho/Mn; red emission; enhanced luminescence;

synthesis parameters; crystal phase transition

Figure: Schematic representation of the synthesis of bright luminescent red emitting NaYF4:Yb/Ho/Mn

upconversion nanophosphors by variation of reaction parameters References [1] K. L. Reddy, V. Srinivas, K. R. Shankar, S. Kumar, V. Sharma, A. Kumar, A. Bahuguna, K. Bhattacharyya, V.

Krishnan, J. Phys. Chem. C, 121 (2017) 11783-11793.

P-11

Alternative route to ligand functionalization for understanding the

role of linker molecule in quantum dot sensitized solar cells

Monika Dahiya and Arijit K. De*

Indian Institute Of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81,

SAS Nagar, Punjab 140306, India.

Email: [email protected], *[email protected]

Dye sensitized solar cells (DSSCs) are inexpensive and have high efficiency but they are

facing limitations due to photo bleaching of dye and short lifetime [1]. Analogous to DSSCs,

Quantum dot sensitized solar cells (QDSSCs) have emerged as a promising approach for light

harvesting. They have opened up new ways of utilizing hot electrons and generate multiple exciton

upon absorption of a single photon. Significant efforts have been made during the past few years

to make them competitive with other existing thin films photovoltaic technologies but demands

further exploration. Our lab is interested in understanding the exciton dynamics within QDSSCs

using femtosecond resolved pump-probe spectroscopy. Due to the presence of bulky ligands

during synthesis, the surface needs to be modified with smaller ligands in order to increase the

adsorption of quantum dots (CdSe) on wide band gap semiconductor (TiO2 or ZnO). Our approach

is to modify the surface with cysteine linkers as they have shorter length which increases the

electron injection rate from quantum dots to wide band gap semiconductor [2]. It was reported that

electron injection from cysteine capped quantum dots is more efficient [3]. Also, we are interested

in understanding the role of trap states formed after functionalization and their role in electron and

hole transport. In this presentation, a new method of ligand functionalization for CdSe quantum

dots and how the dynamics of the charge carriers are modified for the two different approaches of

functionalization will be discussed.

References

[1]I.Robel, V. Subramanian, M. Kuno, P.V. Kamat; Quantum dot solar cells. Harvesting light

energy with CdSe nanocrystals molecularly linked to mesoscopic TiO2 films, Langmuir, 2006,

128, 2385-2393.

[2] J.Chang, Y.Ogomi, C.Ding, Y.Zhang, T.Toyoda, S.Hayase, K.Katayamae, Qing Shen; Ligand-

dependent exciton dynamics and photovoltaic properties of PbS quantum dot heterojunction solar

cells, Phys. Chem. Chem. Phys., 2017, 19, 6358-6367.

[3] X.Xua, S.Giménezb, I.Serób, A.Abateb, J.Bisquertb, G.Xua; Influence of cysteine adsorption

on the performance of CdSe quantum dots sensitized solar cells, Material Chemistry and Physics,

2010, 124, 709-712.

P-12

Identification of Bacterial strains by MALDI-TOF Mass Spectrometry

Rakesh Kumar and Ramdhan Yadav

Department of Biochemistry, Panjab University Chandigarh 160014


The MALDI-TOF (Matrix Assisted Laser Desorption/Ionization) mass spectrometer is a

very fast and usable technique to identify the cellular and protein component of bacteria. MALDI-

TOF uses in science in broad ways but in respect to the molecular weight of protein and peptide

have been used to identify bacteria. Many bacteria such as staphylococcus aureus, bacillus cereus,

pseudomonas fragi etc. are identified by MALDI-TOF MS. The sample of bacteria is ionized with

the help of laser. Population of ion is then passing through the electrostatic field and magnetic

analyzer. The analyzer monitors the selective ions that are able to produce the accurate information

of the sample under vacuum. The present poster covers the MALDI-TOF MS for bacterial

identification.

REFERENCE:

J.P. Anhalt and C. Fenselau; Anal. Chem., (1975) 47: 219–225

P-13

Multifunctional magnetic and fluorescent hybrid core shell NPs containing

exceedingly small iron oxide nanocrystals for multimodal imaging and

biosensing Ashish Tiwari and Jaspreet Kaur Randhawa*

School of Engineering, Indian Institute of Technology Mandi, Himachal Pradesh, India


The present study involves fabrication of biocompatible multifunctional magnetic and fluorescent

hybrid core shell nanoparticles (MFCSNPs) in single step synthesis method. Magnetic core of MFCSNPs

is iron oxide (Fe3O4) providing superparamagnetic properties which can be exploited for magnetic

resonance imaging (MRI) in cancer diagnostics. Fluorescent shell is carbon coating which enable optical

properties in MFCSNPs; saturated with carbonyl and hydroxyl groups making them advantageous for

bioimaging in cancer detection and therapy. Multiple surface functionalities of MFCSNPs offer a choice to

feat them as a drug carrier with efficient drug loading and targeting ability. Structural and morphological

features showed spherical core shell NPs with an average particle size of 230 nm containing small iron

oxide nanocrystals with an average size of 8 nm. Successful carbon coating on iron oxide nanocrystals was

confirmed by STEM images and elemental mapping. MFCSNPs showed superior superparamagnetic

behaviour with minimum coercivity and saturation magnetization of 29.34 emu/gm. CLSM imaging

displayed multicolour fluorescence spectra with tunable excitation wavelength. Achieving strong

fluorescence, superparamagnetic behaviour and good biocompatibility, MFCSNPs can be internalized into

the cells following accumulation in cell cytoplasm, which parade desirable capability for bioimaging in

therapeutic application. Moreover, systemic investigation of in vitro molecular interactions between

MFCSNPs with bovine serum albumin (BSA) were elucidated appropriately. The microenvironmental and

conformational changes of BSA induced by MFCSNPs were investigated by multi spectroscopic methods.

These results suggested that conformational change of BSA was significantly at secondary structure level

and biological activity of BSA was weakened dramatically in the presence of MFCSNPs.

Figure 1. TEM, PL and VSM spectra of MFCSNPs and PL and CD spectra of interaction with BSA.

References 1. Xiao, Lisong, et al. "Water-soluble superparamagnetic magnetite nanoparticles with biocompatible

coating for enhanced magnetic resonance imaging." ACS Nano 5.8 (2011): 6315-6324.

2. Wei, He, et al. "Exceedingly small iron oxide nanoparticles as positive MRI contrast agents." Proceedings

of the National Academy of Sciences (2017): 201620145.

P-14

Ag Nanoparticle Aggregates Assembled on 3D heterojunction Configuration

Using Rhododendron Flower Petals for SERS Applications

Ramachandran Balaji, Nisha Kumari, Vipul Sharma and Venkata Krishnana*


Technology Mandi, Kamand, Mandi 175005, Himachal Pradesh, India.


Novel biomaterial based SERS substrates fabricated on rhododendron flower petal surfaces

is reported in this work. The substrates were fabricated by taking advantage of the unique pattern

of the surface micro/nanostructures found on the petal surface and the SERS activity was

demonstrated by using a model chemical analyte. In one of the cases, a three dimensional

heterojunction mirror-like configuration was created by sputter deposition of a 5 nm thin film of

Au metal followed by assembly of Ag nanoparticle aggregates, which were synthesized via curry

leaf extract, over them to form a hetero nano-junction. This nano-junction based SERS substrate

performed better than another substrate fabricated by simple drop casting of Ag nanoparticle

solution on the flower surface, which could be attributed to the enhanced plasmonic interactions

between the Ag nanoparticle aggregates with the 5 nm Au thin film. Such facile nano-junction

based systems having nanoparticles on 3D heterojunction mirror-like configurations fabricated on

naturally occurring materials can be conveniently used for chemical, forensic and biomedical

analysis.

References:

[1] Vipul Sharma, Ramachandran Balaji, Rajat Walia, Venkata Krishnan, Colloid and Interface

Science Communications 18 (2017) 9–12

[2] V. Sharma, S. Kumar, A. Jaiswal, V. Krishnan, Gold deposited plant leaves for SERS: role of

surface morphology, wettability and deposition technique in determining the enhancement factor

and sensitivity of detection, Chem. Sel. 2 (2017) 165–174.

[3] S.-Y. Chou, C.-C. Yu, Y.-T. Yen, K.-T. Lin, H.-L. Chen, W.-F. Su, Romantic story or Raman

scattering? Rose petals as eco-friendly, low-cost substrates for ultrasensitive surface-enhanced

Raman scattering, Anal. Chem. 87 (2015) 6017–6024.


P-15

SCHOTTKY ANOMALY IN ReBaCuFeO5 (Gd, Ho and Yb)

Surender Lal, K. Mukherjee , C. S. Yadav

School of Basic Sciences, Indian Institute of Technology, Mandi, Mandi-175005, (H.P.) India


Keywords: Multiferroic, Heat capacity, Schottky Anomaly

Double perovskites materials are represented by general formula A'A''B'B''X6 where (A',

A'') sites are occupied by rare or alkaline earth metals, (B', B'') sites are occupied by transition

metal ions and X site is generally occupied by the oxygen or halide ions. Layered perovskite

materials are derivatives of double perovskites in which one of the oxygen is removed from the A'

plane [1]. Layered perovskite materials exhibits interesting structural, magnetic and multiferroic

properties [2,3]. These properties can be tuned by applying additional chemical pressure or

increasing the distortion in the system [4,5]. We present here the results of heat capacity of layered

perovskite ReBaCuFeO5 (Re = Gd, Ho, Yb) compounds, measured at different magnetic field. Low

temperature heat capacity shows an upside turn below 10 K. In the absence of any magnetic

transition, this anomaly is attributed to the Schottky anomaly [6]. This anomaly shifts towards

higher temperature on application of magnetic field. This anomaly can be attributed to the splitting

of ground sate levels of rare earth ions into two or more levels in the presence of crystalline electric

field. The crystalline electric field dominates the exchange interactions at low temperature (T < 10

K).

References

[1] L. Er-Rakho, C. Michel, P. Lacorre, and B. Raveau, J. Solid State Chem. 73, 531 (1988).

[2] V. Caignaert, I. Mirebeau, F. Bouree, N. Nguyen, A. Ducouret, J.-M. Greneche, and B.

Raveau, J. Solid State Chem. 114, 24 (1995).

[3] B. Kundys, A. Maignan, and C. Simon, Appl. Phys. Lett. 94, 72506 (2009).

[4] M. Morin, E. Canévet, A. Raynaud, M. Bartkowiak, D. Sheptyakov, V. Ban, M.

Kenzelmann, E. Pomjakushina, K. Conder, and M. Medarde, Nat. Commun. 7, 13758

(2016).

[5] S. Lal, S. K. Upadhyay, K. Mukherjee, and C. S. Yadav, EPL (Europhysics Lett.) 117,

67006 (2017).

[6] L. Xie, T. S. Su, and X. G. Li, Phys. C Supercond. 480, 14 (2012).

P-16

Orbiton-Phonon coupling in Ir5+(5d4) double perovskite Ba2YIrO6

Birender Singh1, G. A. Cansever2, T. Dey2, A. Maljuk2,S. Wurmehl2,3, B. Büchner2,3 and Pradeep

Kumar1

1School of Basic Sciences, Indian Institute of Technology Mandi,Mandi-175005, India 2Leibniz-Institute for Solid State and Materials Research, (IFW)-Dresden, D-01171 Dresden,

Germany 3Institute of Solid State Physics, TU Dresden, 01069 Dresden, Germany


Ba2YIrO6, a Mott insulator, with four valence electrons in Ir5+d-shell (5d4) is supposed to be non-

magnetic, with Jeff = 0, within the atomic physics picture. However, recent suggestions of non-zero

magnetic order parameter have raised some fundamental questions about its origin. Focussing on

the phonon dynamics, probed via Raman scattering, as a function of temperature and different

incident photon energies, as an external perturbation. Our studies reveal strong renormalization of

the phonon self-energy parameters and integrated intensity for first-order modes, especially

redshift of the few first-order modes with decreasing temperature and anomalous softening of

modes associated with IrO6octahedra, as well as high energy Raman bands suggesting the

proposed magnetic nature may have its origin in strong electron-phonon coupling via orbital

excitations.The distinct renormalization of second-order Raman bands with respect to their first-

order counterpart suggest that higher energy Raman bands have strong contribution from orbital

excitations. Our observation reveals that strong anharmonic phonons coupled with electronic

degrees of freedom via orbital excitations provides a knob for tuning the conventional electronic

levels for 5d-orbitals, and this may give rise to non-zero magnetic order parameter as postulated

in recent theoretical calculations with rich magnetic phases.

References

B. Singh et al., arXiv:1702.00724

P-17

Amalgamated CaTiO3-g-C3N4 Heterojunction Photocatalyst for

Organic Pollutant Degradation Ashish Kumar, Christian Schuerings, Suneel Kumar, Ajay Kumar and Venkata Krishnana*




Perovskite based materials are currently used widely for photovoltaic and photocatalytic

applications, due to their superior properties as compared to the conventional materials. In this

work, a promising amalgamation of organic with inorganic semiconductor photocatalyst (g-

C3N4/CaTiO3) was performed in 1:1 ratio through a facile thermal method.1 The organic

semiconductor (g-C3N4) was prepared through pyrolysis of dicyandiamide, while perovskite

(CaTiO3) was prepared by polyacrylamide gel route.2,3 The as-prepared photocatalyst was

characterized by powder x-ray diffraction (XRD), scanning electron microscopy (SEM),

transmission electron microscopy (TEM), thermogravimetric analysis (TGA), UV-vis diffuse

reflectance spectroscopy (DRS) and photoluminescence (PL) spectroscopy. The mechanistic

analysis revealed that amalgamation of organic semiconductor stimulated the utilization of solar

spectrum by enhancing the light absorption towards visible region, whereas perovskite activated

close interfacial interactions lead to enhanced efficiency of electron migration. The

photoluminescence spectroscopic study (PL) indicated the prolongation of the photogenerated

charge carriers. The photocatalytic activity of the perovskite composite was examined under UV,

visible and sun light by monitoring the degradation a model pollutant dye (Rhodamine B) and a

non-photosensitizing compound (Bisphenol A). The photocatalytic investigations clearly revealed

the dominant solar light harvesting capability of the developed perovskite amalgamated organic

photocatalyst.

References:

(1) K. H. Leong, Z. Z. Tan, L. C. Sim, P. Saravanan, D. Bahnemann and M. Jang, Chemistry

Select 2 (2017) 84.

(2) T. Xian, H. Yang and Y. S. Huo, Phys. Scr. 89 (2014) 115801.

(3) P. Niu , L. Zhang , G. Liu and H. M. Cheng, Adv. Funct. Mater. 22 (2012) 4763.

P-18

Structurally engineered biocompatible molecular probes for live

cell-imaging and localization of native DNA Pankaj Gaur and Subrata Ghosh

School of Basic Sciences, Indian Institute of Technology Mandi,Mandi-175005, India


Because of their vitality toward genetic inheritance, governing and functioning of cellular

activities, nucleic acids have earned the prime focus out of other biomolecules. Therefore, deep

insight of their structural dynamics and its influence on the cellular functioning could be of great

importance in the physiological and pathological investigations. Hence, it became crucial to

visualize their dynamics in the cellular milieu, and the same directed the immense attention of the

researcher for the development of useful techniques for their real time monitoring at cellular level.

In this continuation, fluorescence microscopy using emissive molecular probes has grown as a

non-invasive optical tool for in-vitro/in-vivo cellular imaging to understand the role of various

biomolecules toward physiological changes and their influences at the cellular level. The

promising molecular markers with enhanced optical properties, cytocompatibility, photobleaching

resistance and target specificity constitute the backbone of fluorescence microscopy. Although,

the dedicated efforts led to the appreciable development of the molecular probes and their

successful employment for visualization of nucleic acids, the common shortcomings such as poor

photostability, cell-impermeant nature and photoinduced toxicity restrict their real applicability in

the biological fields. Moreover, the incorporation of aforementioned requisite parameters in a

single molecular probe has been rare and a challenging task. In this concern, we focused our keen

interest to crack these challenges and to bring the appreciable contributions toward the advanced

biochemical research. The molecular probes with a tailored donor-acceptor conjugated (D-π-A and

D-π-A-π-D pull-push systems) molecular architecture have been devised and synthesized. Their

optical behavior was studied both in solution as well as cellular milieu to explore their candidature

as promising DNA markers.

P-19

Modified Atomic Orbital Overlap: Molecular Level Proof of the

Nucleophilic Cleavage Propensity of Dinitrophenol-Based Probes Mangili Venkateswarulu,* Sunil Kumar, and Subrata Ghosh

School of Basic Sciences, Indian Institute of Technology Mandi, Mandi, Himachal Pradesh

175005, India


Out of six possible positional isomers of dinitrophenol, only 2,4-DNP has been used extensively

by many researchers for developing reactive molecular probes. But the question remains

unanswered: why has only the 2,4-isomer emerged as a labile protecting group? To answer this

question, six molecular probes using available DNP isomers were developed and investigated to

evaluate the effect of the extent of atomic orbital overlap on their reactivity. We have proved for

the first time at the molecular level that the o-NO2 group contributes less compared to the p-NO2

group toward the reactivity of 2,4-DNP-based probes. Crystal structure analysis revealed that the

2p orbital of N atom and the 2p orbital of the adjacent ring C atom to which the o-NO2 is attached

are inclined at >30° to each other, leading to substantial reduction in π overlap (as these two p-

orbitals loose coplanar state) resulting in a very weak −M effect of the o-NO2 group, whereas the

2p orbitals of the N atom of the p-NO2 group and the adjacent ring C atom are almost coplanar

(11° inclined to each other), leading to strong π overlap. Hence, the p-NO2 group contributes

largely toward the molecular reactivity through its −M effect.

Reference:

1. M. Venkateswarulu, P. Gaur, S. Sinha, A. Pramanik and S. Ghosh, J. Phys. Chem. C., 2015,

119, 19367-19375.

2. M. Venkateswarulu, Sunil kumar, and S. Ghosh, J. Org. Chem., 2017, 82, 4713–4720.

P-20

Multifunctional Metal organic framework for organic

transformation and photocatalysis application

Harpreet Kaur, M. Venkateswarulu, Pankaj Gaur, Suneel Kumar,Venkata Krishnan and Rik Rani

Koner*

School of Engineering and Basic Sciences, Indian Institute of Technology Mandi, Kamand,

Mandi 175005, Himachal Pradesh, India.

Email id – [email protected],[email protected]

In recent times, there is an enormous demand for developing materials, which can be used as

multifunctional materials for several industrial applications. Among the various kinds of materials,

metal organic frameworks(MOFs) have been found to be promising materials due to their tunable

structural property with different functional groups, high surface area etc.[1]MOFs have interesting

applications in the field of photocatalysis,[2] electrocatalysis as well as in various other areas. In

this direction, cadmium based MOF with 4,4’-bipyridine and 2-aminoteraphthalic acid moieties

has been developed[3]and investigated for sorption of iodine.Subsequently, the captured iodine was

employed for catalyzing various industrially relevant organic transformation reactions.The iodine

loaded MOF showed tremendous catalytic activity in the organic transformation of benzaldehyde

and o-phenylenediamine into benzimidazoles in a very short time (6 hr), which otherwise takes

more than 24h in the presence of simple molecular iodine. The same catalyst also showed

appreciable activity in the synthesis of 2-aminobenzothiazoles.In addition, this developed MOF

showed excellent photocatalytic activity towards the degradation of organic pollutant (MB dye)

under visible light irradiation.

References :

1. Li, Y. L., Zhao, Y., Wang, P., Kang, Y. S., Liu, Q., Zhang, X. D., & Sun, W. Y. 2016,Inorg.

Chem., 55(22), 11821-11830.

2. Wang, C. C., Li, J. R., Lv, X. L., Zhang, Y. Q., &Guo, G. 2014, Energy &Environ. Sci., 7(9),

2831- 2867.

3. Jiang, H. L., Tatsu, Y., Lu, Z. H., & Xu, Q. 2010, J. Am. Chem. Soc., 132(16), 5586-5587.

4. Kaur H.,Venkateswarulu M., Gaur P., Kumar S., Krishnan V., Koner R. 2017, manuscript

under preparation.



P-21

Tuning the surface enhanced Raman scattering activities of gold

nanorods by controlled coating of platinum

R. Gogoi, V. Sharma, N. Sinha, S. Dutt, M. Chawla and P. F. Siril*

Indian Institute of Technology Mandi, Mandi, (.H.P.)


Gold is known to be a very good surface enhanced raman spectroscopy (SERS) active substrate. It can be further

enhanced when it is coated with non SERS active materials like Pt.1 But, the synthesis of core shell nanorods by

the galvanic replacement of silver (Ag) by platinum (Pt) on bi-metallic core shell nanorods (NRs)

having gold (Au) core and silver shell (Au@Ag) resulted in discontinuous coating of Pt over Au

(Au@Pt-DC) NRs due to the high cohesive and surface energies of Pt.2 However, a novel method

has been developed for the preparation of Au NRs having smooth and continuous coating of Pt

(Au@Pt-C NRs) in presence of

sulfuric acid as a source of

selective blocking agent. Here,

the role of the sulfuric acid in the

formation of differently coated

Au@Pt was analysed and the

effect of the nature of Pt shell

(i.e. whether continuous or

discontinuous) on SERS activity of the NRs was investigated with methylene blue (MB).

Additionally, prepared Au@Pt NRs have showed catalytic reduction of MB and 4- nitrophenol in

the presence of NaBH4 with Au@Pt-DC NRs showing almost three times better activity than Au

and Au@Pt-C NRs.

References

[1] L. Guerrini, E. Lopez-Tobar, J.V. Garcia-Ramos, C. Domingo, S. Sanchez-Cortes chem.

Commun., 47 (2011), p. 3174.

[2] E. Bus, J.A. van Bokhoven J. Phys. Chem. C, 111 (2007), p. 9761.

Figure 1: Galvenic replacement of Ag by Pt during the formation Au@Pt NRs.

http://www.sciencedirect.com/science/article/pii/S0021979715302812#!





P-22

Preparation and spectroscopic analysis of fluorescent banana fiber

A. Prasad

National Institute of Technology, Kurukshetra


Banana fiber is a lingo-cellulosic fiber, which obtained from the pseudo-stem of the banana

plant. This constituted of cellulose, hemicellulose, lignin, pectin, wax and water-soluble

components. The abundance of this fiber combined with the case of its processing is an attractive

feature, which makes it a valuable substitute for synthetic fibers. In the present, we have extracted

banana fiber using a unique fiber extraction technique which preserves most of the fiber’s

mechanical and structural properties. The estimated mechanical properties of banana fibers were

found to be a function of diameter, testing speed, density etc. The thermal properties of the

composites have been evaluated using DSC and TGA while structural and spectroscopic properties

were explored using Scanning electron microscopy, Fourier transformed infrared and UV-Visible

absorption spectroscopy, PL etc. The prepared fibers emit bright yellow-red colors; however, a

clear shift in emission band was noticed. Detail result and analysis will be discussed during the

presentation.

P-23

Role of Nitrogen in the Activity Descriptor of Oxygen Reduction

Reaction in Iron based Catalysts

Ankita Mathur1, Aditi Halder2

1School of Engineering, Indian Institute of Technology Mandi, Mandi, HP, India

2School of Basic Sciences, Indian Institute of Technology Mandi, Mandi, HP, India


Transition metal- nitrogen- carbon (M-N-C) based materials are suitable alternative of

platinum and effective electrocatalysts for oxygen reduction reaction (ORR) of polymer electrolyte

membrane fuel cell (PEMFC). Fe-N-C framework show very good catalytic activity towards ORR.

Nitrogen atoms have been found to play a significant role in creating active sites for the adsorption

of oxygen, such that with increase in FeN2 or FeN4 sites, the catalytic activity also increases.

Herein, we have prepared Fe-N-C based material by low cost hydrothermal treatment and annealed

in nitrogen atmosphere at 800°C. The electrocatalysts were characterized by X-Ray Diffraction

(XRD) for crystal structure, Field emission scanning electron microscope (FESEM) for structural

morphology and elemental composition determination, Raman Spectroscopy for vibrational modes

identification and X-Ray photoelectron spectroscopy (XPS) for determining the chemical bonding

between the elements. Electrochemical activity was also evaluated by rotating disc electrode and

rotating ring disc electrode. The reduction of oxygen occurs via four electron pathway, following

first order kinetics, leading to the formation of water as final product. By correlating the results of

physical and electrochemical characterizations it has been concluded that an optimum quantity of

nitrogen atoms create active sites and enhance the activity, beyond which they play no role in

activity descriptor.

Keywords: Polymer electrolyte membrane fuel cell, Oxygen reduction reaction, Non platinum

cathode electrocatalyst, iron oxide, Nitrogen atoms.

P-24

Perovskite (MAPbBr3) quantum dots: a potential color convertor Rajeev Ray, Supriya Ghosh, and Suman Kalyan Pal

Indian Institute of Technology Mandi, Kamand, Mandi, (.H.P.)

[email protected], [email protected]

Nowadays light-emitting diodes (LEDs) are used for both illumination and data communication in

the fields of solid-state lighting (SSL) and visible light communications (VLCs) [1]. However,

suitable materials for white and visible light emitting LEDs are still lacking. In this context, we

synthesize quantum dots (QDs) of MAPbBr3, which show green photoluminescence (PL) with

very high PL quantum yield (QY). The PL lifetime of the synthesized QDs are found to be 14.6

ns. A highly luminescent green emitting LED device was fabricated by embedding MAPbBr3 QDs

in a polymer matrix (PMMA) and using a blue LED. The fabricated device exhibits external

quantum efficiency as high as 47% suggesting the usefulness of the pervoskite QDs as colour

converter. Nonetheless, we investigate carrier dynamics of MAPbBr3 QDs using transient

absorption spectroscopy (TAS) to elucidate their PL properties.

Figure 1. (a) PL decay of MAPbBr3 QDs monitored at 505 nm. (b) Green emitting LED fabricated

using blue LED.

Reference

1. Burchardt, H.; Serafimovski, N.; Tsonev, D.; Videv, S.; Haas, H.VLC: Beyond point-to-

point communication. IEEE Commun. Mag. 2014, 52, 98−105.



P-25

Multiple Exciton Dissociation at CdSe-MoS2 Heterostructure

Aamir Mushtaq, Supriya Ghosh, Abdus Salam Sarkar and Suman Kalyan Pal

School of Basic Sciences and Advanced Material Research Center, Indian Institute of Technology Mandi,

Kamand 175005, H.P, India.


van der Walls heterojunctions of layered transition metal dichalcogenides (TMDs) have shown promise for

the dissociation of excitons via fast charge transfer.1 Nowadays, scientists are trying to combine quantum

dots (QDs) and two-dimensional nanosheets into one nano-heterostucture for efficient energy and charge

transfers. We prepared a heterostructure of CdSe (cadmium selenide) QD and MoS2 (molybdenum

disulfide) nanosheet. Our steady state study reveals that the emission intensity of CdSe QDs found to be

greatly quenched in this heterostructure due to hole transfer from QD to MoS2 nanosheet as shown in the

figure 1(a).2 We have also obtained Transient absorption spectra for CdSe QDs with MoS2 nanosheets

following low laser fluences as shown in the figure 1(b) at 2.58 eV excitation. Our femtosecond transient

absorption studies divulge that exciton dissociates via hole injection in the timescale of 600 ps. Nonetheless,

we demonstrate extraction of two holes via dissociation of biexciton at the QD/nanosheet heterojunction.

We noticed that the first hole injects within 42 ps followed by slow injection of the second one as shown in

figure 2. Our study suggests that the exploitation of multiple exciton generation (MEG) effect by harvesting

multiple holes is possible.

Figure 1. (a) PL spectra of CdSe QDs and CdSe-MoS2 at 2.8 eV excitation. (b) TA spectra of

CdSe QDs with MoS2 nanosheets following 2.58 eV excitation(laser fluence 78J/cm2/pulse)

Figure 2. Biexciton dissociation and extraction of two holes at QD/MoS2 heterojunction.

(1) Hong, X.; Kim, J.; Shi, S.-F.; Zhang, Y.; Jin, C.; Sun, Y.; Tongay, S.; Wu, J.; Zhang, Y.; Wang, F. Ultrafast

charge transfer in atomically thin MoS2/WS2 heterostructures. Nat. Nanotechnol. 2014, 9, 682-686.

(2) Mushtaq, A.; Ghosh, S.; Sarkar, A. S.; Pal; S. K. Multiple Exciton Harvesting at Zero-Dimensional/Two-

Dimensional Heterostructures, ACS Energy Lett. 2017 (DOI: 10.1021/acsenergylett.7b00544).


P-26

Enantioselective gel formation and collapsing: A horizon for chiral

recognition

Diksha Gambhir, Gourab Dey, Venkata Krishnan and Rik Rani Koner*

School of Engineering and School of Basic Sciences, Indian Institute of Technology Mandi,

Kamand, Mandi 175005, Himachal Pradesh, India.

Gels are fascinating materials that can be encountered in everyday life in medicines, food items

and cosmetics. They exhibit interesting behaviors that are neither of a typical solid or a liquid thus

finding applications in a wide variety of fields including biotechnology, pharmacy, chemistry, and

material science. Enantioselective recognition garners a lot of attention due to its crucial role in

controlling events in pharmacological applications such as chiral sensors, enantioselective

separation and catalysis. Enantiomers tend to behave in the same manner in an achiral

environment, whereas in chiral environment they exhibit different properties. Therefore, different

chiral moieties have been designed in the last few decades such as chiral molecules(1), MOFs(2),

polymers(3), supramolecular gels(4) etc.. When chiral moiety is self-assembled into a gel, not only

the site selection but spatial selection could also be enhanced which in turn leads to enhanced chiral

recognition.(5) Thus, many research groups have keen interest in developing supramolecular gels

as chiral sensors.. Herein we report the self-assembling of an amino acid based optically active

pure ligand into gel by the selective incorporation of enantiomeric chiral amines and amino

alcohols. Additionally, the collapsing of gel in presence of different enantiomers validated its

enantioselective nature. The enantioselectivity is further supported by circular dichroism (CD)

spectroscopy.

References:

(1) Xu, S.-Y.; Hu, B.; Flower, S. E.; Jiang, Y.-B.; Fossey, J. S.; Deng, W.-P.; James, T. D.; Gao, H. J.;

Zhao, J. Z.; James, T. D. Chem. Commun. 2013, 49 (75), 8314.

(2) Wanderley, M. M.; Wang, C.; Wu, C.-D.; Lin, W. J. Am. Chem. Soc. 2012, 134 (22), 9050–9053.

(3) Yashima, E.; Iida, H.; Okamoto, Y. In Topics in current chemistry; 2013; Vol. 340, pp 41–72.

(4) Chen, X.; Huang, Z.; Chen, S.-Y.; Li, K.; Yu, X.-Q.; Pu, L. J. Am. Chem. Soc. 2010, 132 (21), 7297–

7299.

(5) Tu, T.; Fang, W.; Bao, X.; Li, X.; Dötz, K. H. Angew. Chemie Int. Ed. 2011, 50 (29), 6601–6605.

P-27

N-doped ZnO-MoS2 Binary Heterojunctions for Visible Light Driven

Photocatalytic Degradation of Tetracycline

Suneel Kumar,a Vipul Sharma,a Kaustava Bhattacharyyab and Venkata Krishnana*

aSchool of Basic Sciences and Advanced Materials Research Center, Indian Institute of


bChemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra, India.


Abstract

Pharmaceutical waste materials, mainly antibiotics such as tetracycline, have generated serious

threats to ecosystem and human life and their degradation into non-toxic compounds is of utmost

importance. In this work, we report the fabrication of binary semiconductor heterojunctions

comprising of N-doped ZnO nanorods loaded with two-dimensional MoS2 nanoflowers in varying

amounts, using a facile hydrothermal synthesis method. These semiconductor heterojunctions have

been demonstrated as highly efficient photocatalysts with enhanced performance under visible

light irradiation for the degradation of a pharmaceutical pollutant, tetracycline. The superior

photocatalytic activity of the heterojunctions can be attributed to the synergistic effect of N-doping

of ZnO and loading of MoS2 leading to higher absorption of visible light, efficient separation of

photo generated charge carriers and rapid charge transfer to reaction sites, as per the conduction

band potentials of both N-doped ZnO and MoS2. In addition, the two-dimensional nanoflower

morphology of MoS2 provides more reaction sites for the adsorption of pollutant, due to its large

surface area. Furthermore, the transfer of holes from the valence band of N-doped ZnO to the

valence band of MoS2 prevents the photocorrosion of N-doped ZnO resulting in enhanced

photostability of the catalyst during the reaction.

.

References:

[1] S. Kumar, V. Sharma, K. Bhattacharyya and V. Krishnan, N-doped ZnO-MoS2 binary heterojunctions: Dual role

of 2D MoS2 in the enhancement of photostability and photocatalytic activity under visible light irradiation for

tetracycline degradation, Mater. Chem. Front., 2017, 1, 1093-1106.


P-28

Lanthanide-doped NaYF4@CdS-Au-RGO nanocomposite with

upconversionluminescence property for photocatalytic applications Ajay Kumar, Kumbam Lingeshwar Reddy, Vipul Sharma, Suneel Kumar,Ashish Kumar and Venkata

Krishnan*

School of Basic Sciences and Advanced Materials Research Center, Indian Institute of Technology

Mandi, Kamand, Mandi 175005, Himachal Pradesh, India.


In our work, we have made an attempt to prepare a novel multicomponent material, lanthanide-

doped NaYF4@CdS-Au-RGO nanocomposite and use this material for photocatalytic application.

Lanthanide-doped NaYF4@CdS core-shell structures decorated with Au nanoparticles supported

on reduced graphene oxide nanosheets were prepared using multi-step hydrothermal method. The

prepared nanoheterostructures were characterized by scanning electron microscopy (SEM),

transmission electron microscope (TEM), Raman spectroscopy, upconversion luminescence

(UCL), powder x-ray diffraction (PXRD) and x-ray photoelectron spectroscopy (XPS). As

Upconversion nanoparticles (UCNP) have the capability of converting infrared radiations into

visible light, they could be exploited for utilizing the infrared region of the sunlight for various

applications. Specifically in this work, we have utilized our multicomponent nanoheterostructures

for photocatalytic applications under natural sunlight. The different components of the prepared

nanoheterostructure could be efficiently used to utilize both the visible and infrared regions of the

sunlight. The photocatalytic application has been demonstrated by investigating the degradation

of a colored and a colorless pollutant.

References

(1) K. L. Reddy, M. Rai, N. Prabhakar, R. Arppe, S. B. Rai, S. K. Singh, J. M. Rosenholm, and V. Krishnan,

Controlled synthesis, bioimaging and toxicity assessments in strong red emitting Mn2+ doped NaYF4:

Yb3+/Ho 3+ nanophosphors. RSC Advances, 2016. 6(59), 53698-704.

(2) Z. Chen, S. Liu, M. Yang, and Y. Xu, Synthesis of Uniform Cds Nanospheres/Graphene Hybrid

Nanocomposites and Their Application as Visible Light Photocatalyst for Selective Reduction of Nitro

Organics in Water, ACS applied materials & interfaces, 2013. 5, 4309-19. (3) J. Zhang, Y. Huang, L. Jin, F. Rosei, F. Vetrone, and J. P. Claverie, Efficient Upconverting Multiferroic

Core@Shell Photocatalysts: Visible-to-Near-Infrared Photon Harvesting. ACS Applied Materials &

Interfaces, 2017, 9(9), 8142-50.

(4) Y. Tang, W. Di, X. Zhai, R. Yang, and W. Qin, NIR-responsive photocatalytic activity and mechanism of

NaYF4: Yb, Tm@ TiO2 core–shell nanoparticles. ACS Catalysis, 2013, 3(3), 405-12.

P-29

Spin-phonon coupling and exchange interaction in Gd substituted

YFe0.5Cr0.5O3

Karan Singh* Mohit K. Sharma and K. Mukherjee

School of Basic Sciences, Indian Institute of Technology Mandi, Mandi 175005, Himachal

Pradesh, India


We report the evolution of physical properties due to partial substitution of Gd on the Y site in a

mixed metal oxide YFe0.5Cr0.5O3.This compound exhibits negative magnetization at low applied

fields. Our investigations on Y1-xGdxFe0.5Cr0.5O3 (x = 0.0, 0.2, 0.4 and 0.6) compounds is

carried out through magnetization and Raman spectroscopy studies. It is observed that even with

20% Gd substitution, the negative magnetization observed in YFe0.5Cr0.5O3 is suppressed. Due

to magnetic rare earth ion Gd3+, additional exchange interaction of the form GdO-Fe/Cr dominates

the magnetic interaction arising due to the transition metal ions. This results in positive

magnetization in Gd-substituted compounds. Temperature dependent Raman spectroscopy along

with magnetization studies revealed that the observed shifts of Raman mode is due to spin-phonon

coupling. Hardening of Raman mode observed below 240 K in YFe0.5Cr0.5O3 weakens and

softening of phonon modes was observed for Y0.4Gd0.6Fe0.5Cr0.5O3 compound. This implies

that additional magnetic interactions due to Gd ions play a dominating role in dictating the

behavior of the Gd-substituted compounds.

P-30

Facile Synthesis Of Pristine Graphene-Palladium Nanocomposites

With Extraordinary Catalytic Activities Using Swollen Liquid

Crystals

Tripti Vats1, Sunil Dutt2 , Raj Kumar 3and Prem Felix Siril 4

1 Indian Institute of Technology Mandi (IIT Mandi),Mandi ,INDIA

2,3,4 Indian Institute of Technology Mandi (IIT Mandi),Mandi ,INDIA


Amazing conductivity, perfect honeycomb sp2 arrangement and the high theoretical surface area

make pristine graphene as one of the best materials suited for application as catalyst supports.

Unfortunately, the low reactivity of the material makes the formation of nanocomposite with

inorganic materials difficult. Here we report an easy approach to synthesize nanocomposites of

pristine graphene with palladium (Pd-G) using swollen liquid crystals (SLCs) as a soft template.

The SLC template gives the control to deposit very small Pd particles of uniform size on G as well

as RGO. The synthesized nanocomposite (Pd-G) exhibited exceptionally better catalytic activity

compared with Pd-RGO nanocomposite in the hydrogenation of nitrophenols and microwave

assisted C-C coupling reactions. The catalytic activity of Pd-G nanocomposite during nitrophenol

reduction reaction was sixteen times higher than Pd nanoparticles and more than double than Pd-

RGO nanocomposite. The exceptionally high activity of pristine graphene supported catalysts in

the organic reactions is explained on the basis of its better pi interacting property compared to

partially reduced RGO. The Pd-G nanocomposite showed exceptional stability under the reaction

conditions as it could be recycled upto a minimum of 15 cycles for the C-C coupling reactions

without any loss in activity.


P-31

Highly linear response Piezoresistive Strain Sensor based on

PDMS/g- C3N4/Graphene Heterostructure with tunable Bandgap

Sk Riyajuddin, Khushboo Soni, Aakanksha Sud, Sushil Kumar, Ehesan Ali, Kaushik Ghosh*

Institute of Nanoscience & Technology, Habitat Centre, Phase-10, Sector-64, Mohali- 160062,

India

Fig 1: Different Stacking pattern of graphene/gC3N4

Abstract:

Layered graphitic carbon nitride exhibit anomalous piezoresistivity attributed to the presence of

periodically spaced triangular holes resulting into a significant change in polarization on the

application of strain[1].This strain has also been used to modulate the electronic bandstructure of

graphene thereby enhancing piezoresistive behavior. Here Graphitic carbon nitride (g-C3N4)

nanosheets were encapsulated between a transparent and flexible heterostructures and uniaxial

strain upto ~22% was applied by two point bending setup. Resistance change has also been

reflected in IV characteristics with varying strain. This experimental analysis are strongly

supported by First-Principle Density Functional theory which predict a band-gap opening of

2.46eV for graphene/gC3N4 heterostructures under 20% uniaxial strain. For performing DFT we

Fig2: Band gap of graphene/gC3N4 bilayer

(a)

Graphene grown

on Cu foilC3N4 solution

Drop castPouring

PDMS

Curing

PDMSCopper

Etching

PDMS/gC3N4/Graphene

HeterostructureGraphene

Copper

PDMS

g-C3N4

(b)Bend 3(Max Bend)

No Bend

Bend 2

Bend 1

PDMS

Heterostructure

Graphene

Copper

PDMS

g-C3N4

Graphene grown

on Cu foil

Drop Casting of

C3N4 solution

Pouring

PDMS liquid

Curing PDMS

Etching of Copper

PDMS/gC3N4/Graphene

Heterostructure

(a)

0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.22 0.24

0.10

0.15

0.20

0.25

0.30

R

/R0

0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.22 0.24

-0.24

-0.22

-0.20

-0.18

-0.16

-0.14

-0.12

-0.10

-0.08

I/

I 0

(c)

0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.22 0.24

0.0

0.4

0.8

1.2

1.6

2.0

Gauge Factor

Sensitivity

Ga

ug

e F

acto

r/S

en

siti

vit

y(

(d)

-1.0 -0.5 0.0 0.5 1.0

-5.00E-012

0.00E+000

5.00E-012

1.00E-011

1.50E-011

2.00E-011

2.50E-011

3.00E-011

I

V

PDMS / g-C3N

4 Max Bend

PDMS/ Graphene Max Bend

(e)

0.0 0.5 1.0

0.00E+000

2.00E-012

4.00E-012

6.00E-012

8.00E-012

1.00E-011

1.20E-011

I

V

PDMS / Graphene No Bend

PDMS / Graphene Max Bend

(f)

0.0 0.5 1.0

1.00E-011

2.00E-011

3.00E-011

4.00E-011

No Bend

Bend 1

Bend 2

Bend 3

I

V

(g)

0.0 0.5 1.0

0.00E+000

5.00E-012

1.00E-011

1.50E-011

2.00E-011

2.50E-011

3.00E-011

3.50E-011

I

V

PDMS/ g-C3N

4 Max Bend

PDMS/ g-C3N

4 No Bend



(h)

(c)

(d)

(e)(f)

(b)

0.00 0.05 0.10 0.15 0.20 0.25

-0.25

-0.20

-0.15

-0.10

-0.05

0.00

I/

I 0

Strain (%)

Equation y = a + b*x

Weight No Weighting

?$OP:A=1 Intercept

?$OP:A=1 Slope

0.0 0.5 1.0

12

18

24

30

36 0%

7.6%

15.2%

22.2%

Cu

rren

t (

A)

Voltage (V)

500 1000 1500 2000 2500 3000

PDMS

Raman shift (cm-1)

PDMS/Graphene

Inte

nsi

ty

PDMS/C3

N4/Graphene

480

605

699 PDMS/ g-C3N4/Graphene Max Bend

PDMS/ g-C3N4/Graphene No Bend



0.0 0.5 1.00

5

10

15

20

25

30

35

Cu

rren

t (

A)

Voltage (V)

0 4 8 12 16 20 24

0.00

0.05

0.10

0.15

0.20

0.25

0.30 Data points

Linear fit

R

/R0

Strain (%)

Equation y = a + b*x

Weight No Weighting

Residual Sum of Squares

6.62963E-4

Pearson's r 0.99341

Adj. R-Square 0.98028

?$OP:A=1 Intercept

?$OP:A=1 SlopeGF = 1.38

Fig3: Increase in relative resistance change with the

strain

Fig4: Band structure opening in graphene/gC3N4

bilayer

consider the generalized gradient approximation (GGA) with PBE-D2 fictional using the plane

wave basis Vienna Ab initio Simulation package (VASP) code. The structural optimization and

electronic structure calculations, the convergence tolerance of force on each atom was set at 0.01

eV Å-1. The convergence criterion for energy is chosen as 10-6 eV. The 2-D Brillouin zone is

sampled by 11x11x1 k-points within the Monkhorst-Pack scheme. The graphene/g-C3N4

heterostructure was constructed using a supercell which contains one g-C3N4 monolayer and one

graphene monolayer. The lattice parameters of graphene and g-C3N4 are 2.46 Å and 7.10 Å,

respectively. The lattice parameter of g-C3N4 is about three times larger than graphene monolayer,

which means a 1x1 supercell g-C3N4 and a 3x3 supercell graphene are used .In geometric

optimization, the position of all atoms in supercell are fully relaxed but the shape and volume of

supercell are fixed. We consider four staking patterns which are as follows(1)pattern I ,N atoms of

g-C3N4 are placed above C atoms of the graphene .(2)pattern II, C atoms of g-C3N4 are placed

above C atoms of graphene. (3) Pattern III, N and C atoms of g-C3N4 are placed right above C

atoms of graphene. (4) Pattern IV, part of C atoms of g-C3N4 are placed on bridge sites of graphene

surface as shown in Fig 1. Among all, pattern II (C atoms of g-C3N4 are placed above C atoms of

graphene) is more favourable than others because of higher binding energy. For understanding the

effect of band gap changes with strain applications [2]we have applied a uniaxial strain from -12%

to +20 % on pattern II (most stable) with interlayer distance of 3.14 Å .We found that the pattern

II can withstand strain from -4% to +20% without distorting the structure. For strains less than -

4% the structure gets unstable moreover the bilayer will be bent. The band gap increases with

increasing applied strain.[3]Fig2. For the strain of -6% the band gap increase to 0.64 eV and it

increase to 2.46 eV for strain of +20%. These results strongly support the enhancement of

resistance on the application of strain which may pave the way for tuning the bandgap of

semiconducting materials. Moreover, the proposed heterosture can serve as a good alternative for

developing new sensor which can be embedded into structural material and operate as

multifunctional sensor with high strain resolution on nanoscale.

References:

[1] M. Zelisko, Y. Hanlumyuang, S. Yang, Y. Liu, C. Lei, J. Li, P.M. Ajayan, P. Sharma,

ARTICLE Anomalous piezoelectricity in two-dimensional graphene nitride nanosheets, Nat.

Commun. 5 (2014).

[2] Xinru Li, Ying Dai, Yandong Ma,Shenhao Han , Baibiao Huang,Phys. Chem. Chem. Phys.,

2014.

[3] M.M. Dong,C.He,W.X.Zhang ,J.Mater.Chem.C,2017.

P-32

Dielectric Relaxation Phenomena of N,N-Dimethylformamide in

Different Solvents from Conductivity Measurement under 9.90 GHz

Electric Field.

Soumya Sundar Pattanayak, Tushar Bachar, Swagatadeb Sahoo

Department of Electronics & Instrumentation Engineering, National Institute of Technology,

Silchar, Assam 788010, India.


Dielectric relaxation studies of N,N-dimethylformamide(DMF)(j) dissolved in various nonpolar solvents(i)benzene

(C6H6),dioxane (C4H8O2) and carbon tetracholaride (CCl4) at 250,350,450 and 550C are attempted by measuring the

conductivity of the solutions under 9.90 GHz electric field using Debye theory.Microwave has capacity to detect weak

molecular association[1,2].Measured dielectric properties are an intermediary vehicle for understanding, explaining

and empirically relating certain physico-chemical properties of the test material[3,4].Permittivity(εij) of polar-non

polar liquid mixture is measured using Rohde & Schwarz made ZNB-20 Vector Network Analyzer, Dielectric

Assessment Kit (DAK) and DAK Evaluation software .The estimated relaxation time (τj’s) and dipole moment (µj’s)

agree well with the reported values[5] signifying the validity of the proposed method. Solute-solvent and solute-solute

molecular associations are ascertained in different molecular environments[6,7]. The associational aspects are taken

into consideration from theoretical µtheo from the standpoint of inductive, mesomeric and electromeric effects within

the polar groups of the molecules. The thermodynamic energy parameters are calculated from Eyring rate theory to

predict the molecular dynamics of the system[8].

20 30 40 50 60

1.00E-029

1.20E-029

1.40E-029

1.60E-029

(I)

(II)

(III)

j

t in 0C

a)

b)

Figure 1. Variation of µj’s of polar-nonpolar

mixture at 250, 350, 450 and 550C temperatures

under 9.90 GHz electric field. (I) ── ──

DMF+C6H6 (II) ── ── DMF+ dioxane (III)

── ── DMF + CCl4 respectively.

Figure 2. Solute-solvent and solute-solute molecular

associations: a) DMF + CCl4 b) DMF + DMF.

References: [1] M. Robinovitz, A. Pines J. Am .Chem. Soc., 1969, 91(7), pp 1585-1589.

[2] R. Kumar, R. K. Chaudhary, V. S. Rangra Indian . J. Phys., 2012, 86(7), pp. 635-640.

[3] S. Sahoo , S. K. Sit Mat. Sc. EnggB., 2009, 163, pp. 31-39.

[4] S. Sahoo , S. K. Sit Can. J. Phys., 2016, 94, pp. 1-12.

[5] K. V. Gopalakrishna Trans. Faraday Soc., 1957, 53, pp. 767- 770.

[6] S. K. Sit, K. Dutta, S. Acharyya, T. Pal. Majumder , S. Roy Journal of Molecular Liquids., 2000, 89, pp. 111-126.

[7] S. Sahoo , S. K. Sit Pramana. J. Phys., 2017, 88, pp. 11-23.

[8] S. Sahoo,T. R. Middya , S. K. Sit Pramana. J. Phys., 2014, 83(4), pp. 579-595.


SPECTROSCOPY OF EMERGING FUNCTIONAL MATERIALS, OCT 9-10, 2017

The following committees have been formed for the organization of the symposium.

Registration & Welcome

Dr. Ajay Soni (Convener)

Members: Dr. Rik Rani Koner, Ms Stuti Sharma, Mr Supriya Ghosh, Juhi Pandey, Dr Dushyant

Kushavah, Diksha Gambhir, Shailija Sharma, Bulti Pramanick, Ms. Diksha Thakur

Program and Venue management

Dr Jaspreet Kaur (Convener)

Members: Dr Suman Kalyan Pal, Mr Prakash Negi, Mr Aamir Mushtaq, Ashish, Abdus Salam

Sarkar, Somnath Acharya

Accommodation & Transportation

Dr. Kaustav Mukherjee (Convener)

Members: Dr Pradeep Kumar, Mr Pavin Samuel, Mr. Rakesh Bhatt, Kavita Yadav, Rajeev Ray,

Birender Singh, Mohit Kumar Sharma

Food & Refreshments

Dr. Prem Felix Siril (Convener)

Members: Mr Anoop Kumar, Rituporn Gogoi, Surender Lal, Prateep Singh Sagara, Nagaraju

Nakka

Public Relation & Media Management

Dr. Chandra Shekhar Yadav (Convener)

Members: Dr. Subrata Ghosh, Ms. Chandan Sharma, Santu Nandi

INDIAN INSTITUTE OF TECHNOLOGY MANDIiitmandi.ac.in/workshops/SEFM/files/Abstract_Booklet.pdf ·...

Documents

Transcript of INDIAN INSTITUTE OF TECHNOLOGY MANDIiitmandi.ac.in/workshops/SEFM/files/Abstract_Booklet.pdf ·...