Surface Enhanced Raman Spectroscopy (SERS) and …

Surface Enhanced Raman Spectroscopy (SERS) and Databases

for the Characterization of Dyes

Deanna O’Donnell, Ph.D.

The following research was conducted at

City College of New YorkMetropolitan Museum of Art

New York, NY

Trace Evidence SymposiumKansas City, Missouri

August 11th, 2011

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Research Objectives• To validate SERS in a forensic context, and show the conditions under which

Raman spectroscopy and especially SERS contribute to the value of forensic science.

• To compare both SERS and normal Raman spectra, and to explore the conditions in which each may be of value.

• To validate certain specialized SERS techniques

• To provide useful protocols for use of field workers

• To provide a searchable database for rapid and reliable field use.

Patrick Buzzini - Forensic & Investigative Science Program,West Virginia University

Marco Leona - The Metropolitan Museum of Art, New YorkPhilip Antoci - NYPD Crime LaboratoryJohn Lombardi - Center for the Analysis of Structures and Interfaces,

City College of New York 2

Principle Investigators (left to right):

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Why Raman Spectroscopy?

600 400 200 0 -200 -400 -600

Anti-Stokes

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0

31

2

21

7

- 2

17

- 3

12

- 4

60

o

Stokes

Raman Shift cm-1

Stokes and Anti-stokes Raman Spectrum of CCl4

217 cm-1 312 cm-1 460 cm-1

E1

E0

StokesScattering

Anti-StokesScattering

RayleighScattering

0- mn 0+ mn0

virtualstates

mn mn

Em m

Em nmn

IR Absorption

Raman is non-destructive and allows in-situ detectionRaman spectra may readily be obtained in aqueous solution (not possible with IR)

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Why Raman Spectroscopy?

600 400 200 0 -200 -400 -600

Anti-Stokes

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0

31

2

21

7

- 2

17

- 3

12

- 4

60

o

Stokes

Raman Shift cm-1

Stokes and Anti-stokes Raman Spectrum of CCl4

217 cm-1 312 cm-1 460 cm-1

E1

E0

StokesScattering

Anti-StokesScattering

RayleighScattering

0- mn 0+ mn0

virtualstates

mn mn

Em m

Em nmn

IR Absorption

Raman is non-destructive and allows in-situ detectionRaman spectra may readily be obtained in aqueous solution (not possible with IR)

However…..Normal Raman intensity is weak & fluorescence can contaminate spectrum

Solution!!Surface Enhanced Raman Scattering (SERS)

Surface Enhanced Raman Spectroscopy (SERS)

Silver Particle

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Molecule in solution

Silver Particle

Molecules on silver surface

Surface Plasmon Resonance

Advantages:• Highly sensitive: Very large enhancements of the Raman signal. This

enables us to detect and identify extremely small quantities of trace chemicals.

• Suppresses fluorescence: Suppression of fluorescence interference, which normally makes such identification impossible.

• Type of metal nanoparticle; usually silver• Size and shape of particle• Excitation wavelength• Presence of ions such as Cl -, SO4

2-, NO3- enhanced electric field

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Factors that alter SERS intensity:

Silver Particle

Molecules on silver surface

Surface Plasmon Resonance

Advantages:• Highly sensitive: Very large enhancements of the Raman signal. This

enables us to detect and identify extremely small quantities of trace chemicals.

• Suppresses fluorescence: Suppression of fluorescence interference, which normally makes such identification impossible.

• Type of metal nanoparticle; usually silver• Size and shape of particle• Excitation wavelength• Presence of ions such as Cl -, SO4

2-, NO3- enhanced electric field

7


Factors that alter SERS intensity:

SERS has its own set of challenges…• small number of compounds studied so far• large difference in SERS efficiency even for closely

related compounds• lack of searchable databases• interferences due to impurities or matrix components

(not a separation technique)• SERS still requires removing a sample - however

microscopic - from the object under analysis

Instrumentation

The Metropolitan Museum of Art

City College of New York

488nm, 633 nm and 785 nm

488nm, 514 nm, 633 nm and 785 nm

488nm, 514 nm, 593 nm, 633 nm

and 785 nmTi-sapphire laser

Dye laser

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x and y focus

stage

objective

cutoff filterwavelength

specific

z focuscourse/fine

DETECTORSOURCE

488 nm514.5 nm632.8 nm785 nm

Raman Microscope

Basic Steps to SERS

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5 l of Ag colloids 1 l of 10-4-10-7 M aqueous dye

1 l of 0.5-0.1 M aggregate

Current Research Projects

• Need ways to acquire trace amounts of analyte in a “non-destructive manner”Gel Extraction

• Need a reliable substrate to yield reproducible spectraSERS substrate

Developing Methods Applications

• Art History/Conservation

Xanthene Dyes

• Forensic Science: Controlled Substances

SERS + Amphetamine

• Forensic Science/Anthropology

SERS of Tattoo Inks

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Extraction Method Refine Technique Application: Dyes Application: Drugs Application: Tattoos

Gel Extraction Method

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GOAL: Develop Non-Destructive Gel Extraction Method

Idea

• Ink or dye can be extracted from a medium using a hydroxy gel

• The gel extracts such a small amount of dye that it leaves the test subject virtually unchanged

o Important in trace analysis

• The extracted dye can then be analyzed and identified using normal Raman spectroscopy or SERS

Model System

• Ball Point Pen Ink on Whatman FilterPaper



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Questioned Document Extraction Materials

Gel in extraction

solvent(1% EDTA in

a 1:1 H2O and DMF)

Gel Size

1 mm

Position of the Gel

Gel

Microscope Slide

Gel, post extraction

Area of Analysis

Before

After

Gel with 5 l Ag NPsAg NPs

Dispersive Raman Scope



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SERS spectrum of Extracted Ink on hydroxy gel

Identification of Ink Component

Pen Extract

Methyl Violet

Multiple Extractions from Same Sample Area

First Extraction

Second Extraction


Conclusion• The gel extraction method is a fast, simple, versatile, and non

destructive method for extracting inks and dyes • Coupled with SERS, it becomes a powerful tool for chemical

analysis

Nondestructive Identification of Natural and Synthetic Organic Colorants in Works of Art by Surface Enhanced Raman Scattering, Leona, M.; Decuzzi, P.; Kubic, T.A.; Gates, G.; Lombardi , J.R., Anal. Chem., 2011, 83(11), 3990–3993.

http://upload.wikimedia.org/wikipedia/commons/c/cd/Methyl_Violet_10B.png

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GOAL: Produce and Characterize Reproducible/Stable Ag surface for SERS

Historic Method:Lee-Miesel Silver NPs (AgNO3 + citrate)

broad absorption (FWHM > 120nm)broad size distribution (3 - 50 nm)not stable over time

Our Method:Microwave Reduction (Ag2SO4 + glucose + citrate)

narrow absorption (FWHM ~ 50 nm)narrow size distribution (3 - 10 nm)stable over 5 - 12 monthsreproducible SERS spectra over time

Refining SERS TechniqueMicrowave Silver NPs

AgNO3 (aq) + citrate Ag 0 Ag Nanoparticles (NP) oxidizing

agent

reducing agent

one hour

Ag2SO4 (aq) + sugar (+ citrate) Ag 0 Ag NP

90 sec

oxidizing agent

reducing agent


Leona, M., PNAS, 2009, 106 (35), 14757-14762

Lee, P.C.; Meisel, D., J. Phys. Chem., 1982, 86, 3391-3395.

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Historic Method:Lee-Miesel Silver NPs (AgNO3 + citrate)

broad absorption (FWHM > 120nm)broad size distribution (3 - 50 nm)not stable over time

Our Method:Microwave Reduction (Ag2SO4 + glucose)

narrow absorption (FWHM ~ 50 nm)narrow size distribution (3 - 10 nm)stable over 5 - 12 monthsreproducible SERS spectra over time

Microwave Silver NPs

200 300 400 500 600 700 8000.0

0.5

1.0

1.5

O

D

Wavelength nm

via microwave reduction

with AgSO4

via Lee-Miesel method

with AgNO3

lmax = 400 nmFWHM = 56 nm

lmax = 422 nmFWHM = 125 nm

Lee-MieselAgNO3

MicrowaveAg2SO4

Lee-Miesel

MicrowaveAg2SO4


Microwave Silver

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SERS Model System:4-mercaptopyridine

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0.0

0.2

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0.6

0.8

1.0

1.2

1.4

O

D

wavelength nm

measured n days after synthesis

0 days

7 days

14 days

145 days

200 300 400 500 600 700 800

0.0

0.2

0.4

0.6

0.8

1.0

1.2

O

D

wavelength nm

Different Lots of Particles

measured n days after synthesis

145 days

55 days

0 days


SERS of Various Dyes Classes


Dye Class Publication

Protoberberines

Arylmethane

Surface-enhanced Raman Spectroscopy study of the red dye laccaic acidCañamares, M.V., et al., J. Raman Spectrosc., 2007, 38, 1259-1266.

Surface Enhanced Raman Spectroscopy of Indanthrone and FlavanthroneChang, J.; et al., J. Raman Spectrosc., 2009, 40, 1557-1563.

Raman and Surface Enhanced Raman Spectra of Flavone and Several Hydroxy-Derivatives

Teslova, T.; et al., J. Raman Spectroscopy, 2007, 38, 802-818.

Raman and Surface Enhanced Raman Spectra of Chrysin, Apigenin and LuteolinCorredor, C.; et al., Vibrational Spectroscopy, 2009, 49, 190-195.

Raman and Surface Enhanced Raman Spectra of 7 and 3’,4’ HydroxyflavoneCañamares, M.V.; et al., Journal of ePreservationScience (Proceedings of the IRUG-8, Vienna Austria, Conference), 2009, 6, 81-88.

DFT, SERS, and Single Molecule-SERS of Crystal VioletCañamares, M.V.; et al., J. Phys. Chem. C, 2008, 112, 20295-20300.

Application of Raman spectroscopy and surface-enhanced Raman scattering to the analysis of synthetic dyes found in ballpoint pen ink

Geiman, I.; et al., J. Forensic Sci., 2009, 54, 947-952.

Surface-enhanced Raman scattering of protoberberine alkaloidsCañamares, M.V.; et al., J. Raman Spectrosc., 2008, 39, 1907-1914.

Flavones

Anthraquinones

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Art History Application

• Want to Identify Dyes in Art

o Art Conservation

o Art History

o Archeology

• large number of dye classes

o we have investigated 10 dyes classes (75 dyes total)

• Van Gogh was known to use Xanthene Dyes

GOAL: Characterize SERS spectrum of Halogenated Xanthene Dyes

FlouresceinFrom Xanthene Dye Family


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Xanthene Dyes: A Spectroscopic Study

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Eythrosine

Rose Bengal

Eosine

Phloxine

Fluorescein

Research Strategy:

Acquire normal Raman spectrum of each dye

Acquire SERS spectrum of each dye

laser

solid dye

solid dye

Ag NP(aq)

laser

dye on Ag(aq)

normal Raman

spectrum

SERSspectrum

Assign Raman Bands to Vibrational Modes

Generate SERS Library


SERS spectra

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Xanthene Dyes: A Spectroscopic Study

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Eosine

Erythrosine

Phloxine

Rose Bengal

Raman Shift cm-1

1700 1600 1500 1400 1300 1200 1100 1000 900 800

Raman Shift cm-1

flourscein

eosine

erythrosine

phloxine

rosebengal

Normal Raman spectra

• Spectra varies upon Halogenation• Should be able to differentiate in

mixtures


Surface-Enhanced Raman Scattering of Phenethylamines

Ecstacy

Phenethylamine

Over 175 different Phenethylamines


The METH makeover

Previous SERS work on Controlled Substances:“Surface-Enhanced Raman Spectroscopy for Trace Identification of Controlled Substances: Morphine, Codeine, and Hydrocodone”Rana, V.; Cañamares, M.V.; Kubic, T.; Leona, M.; Lombardi, J.R.; Journal of Forensic Sciences, 2010, 55(1), 200-207.

wide variety of therapeutic classes, including but not limited to..

• appetite depressants• vascoconstrictors• psychotropic drugs • bronchodilators

• antidepressants• Antiparkinson agents• neurotransmitters 21

SERS of Phenethylamines

Research Strategy:

Acquire normal Raman spectrum of Phenethylamines

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GOAL: Acquire SERS of Amphetamines for trace analysis

Phenethylamine

MDMA (Ecstasy)

Ephedrine

Amphetamine

Methamphetamine

Acquire SERS spectrum of Phenethylamines, refining experimental conditions

laser

solid drug

solid drug

Ag NP(aq)

laser

drug on Ag(aq)

normal Raman

spectrum

SERSspectrum


Normal Raman and SERS of Phenethylamine

Phenethylamine

1600 1400 1200 1000 800 600

0

494621

1002

1029

1207

15861

605

14

9

21

7

28

2

34

249

261

9

74

0

77

881

7

89

994

2

99

91

02

5

10

74

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37

11

72

12

04

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61

13

13

13

91

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54

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03

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75

1

99

9

10

25

16

00

11

90

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79

16

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NR Phenethylamine

SERS Phenethylamine 1

58

3

Raman Shift cm-1

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1600 1400 1200 1000 800 600

Raman Shift cm-1

MDMA

Ephedrine

Methamphetamine

Amphetamine

Phenethylamine

SERS of Phenethylamine

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Surface-Enhanced Raman Scattering of MDMA (Ecstasy) and AnalogsTaplin, F.; O’Donnell, D.; Kubic, T.; Leona, M.; Lombardi, J.R., Forensic Science International - submitted

Raman Scattering of Tattoo Inks

Pulled from the Headlines….

Worst tattoo ever? Amateur pranks friend by giving him obscene ink instead of yin-yang he asked forNY DAILY NEWSTuesday, October 26th 2010, 4:28 PM

Anthropological Implications

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Extraction Method Separation Method Refine Technique Application: Dyes Application: Drugs Application: Tattoos

GOAL: Acquire SERS of Tattoo Inks

Raman Scattering of Tattoo Inks

Skin Candy (17)- USA

Iron Works Brasil (10)- Brazil

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• Most work on Tattoo inks in the past have used Absorption Spectroscopy, IR, XRD and SEM.

• Some work has been done using Dispersive Raman looking at carbonous materials in tattoos*

* Poon, K.; I. Dadour, I.; McKinley, A., J. of Raman Spectroscopy, 2008, 39, 1227-1237.

Poon, K.W.C., M.S./Ph.D. Thesis, The University of Western Australia, 2008.

C:\Users\Michelle\Documents\Administrative Documents\PhD DISSERTATION\The Metropolitan Museum of Art\9-01-2010 Tattoo Inks\IWB Vermelho (Red).2 IWB Vermelho (Red) Iron Works Brasil Tattoo Inks9/1/2010

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C:\Users\Michelle\Documents\Administrative Documents\PhD DISSERTATION\The Metropolitan Museum of Art\9-01-2010 Tattoo Inks\IWB Vermelho (Blue aggregate).2 IWB Vermelho (Blue aggregate) Iron Works Brasil Tattoo Inks9/1/2010

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RAW DATARed Region (785nm)

RAW DATABlue Aggregate (785nm)

50x


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C:\Users\Michelle\Documents\Administrative Documents\PhD DISSERTATION\The Metropolitan Museum of Art\9-01-2010 Tattoo Inks\IWB Vermelho (Blue aggregate).2 IWB Vermelho (Blue aggregate) Iron Works Brasil Tattoo Inks

C:\Users\Michelle\Documents\Administrative Documents\PhD DISSERTATION\The Metropolitan Museum of Art\9-01-2010 Tattoo Inks\IWB Vermelho (Red).2 IWB Vermelho (Red) Iron Works Brasil Tattoo Inks

9/1/2010

9/1/2010

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Vermelho-Iron Works BrasilIngredients (according to packaging; translated): toxic pigment (mineral/organic) deionized water, surfactant, humectant, preservativeNOTE: No color information provided

Tattoo Inks - Normal Raman Spectra

Overlay of Normal Raman Spectra to demonstrate differences



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A Closer Look at the Red Aggregate


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Raman Shift cm-1

Experimental Normal Raman Spectrum

Literature Normal Raman SpectrumPigment Red 170CI 12475

Scherrer, N., Z., et al., Spectrochimica Acta Part A, 2009, Vol. 73, 505-524.

96

4 15

51

15

13

14

89

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59

14

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13

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0

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4686

2

77

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61

157

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51

349

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42

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37

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07

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10

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Of the 38 major bands in Pigment Red 170, the red aggregate matched 30 bands

28


16

06

15

26

14

90

14

51

14

34

13

63

13

43

13

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A Closer Look at the Blue Aggregate


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Raman Shift cm-1

Of the 22 major bands in Pigment Blue 15:2, the blues aggregate matched 17 bands

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Pigment Blue 15:2C.I 74160

68

0

77

859

4

13

06

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30 1

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Scherrer, N., Z., et al., Spectrochimica Acta Part A, 2009, Vol. 73, 505-524.

Experimental Normal Raman Spectrum

Literature Normal Raman Spectrum

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633 nm 785 nm

Razberry CreemSkin Candy

Pigment Red 122

Normal Dispersive Raman Spectrum excited at 488 nm


SERS of Tattoo Inks

• High Fluorescence in Background• Pigment not identifiable by Normal

Dispersive Raman

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36

13

14

30

15

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Razberry CreemSkin Candy

Pigment Red 122

SERS Spectrum excited at 488nm

Note: Enhancement of three weak bands ( 1568, 1316 and 1238 cm-1) and additional peaks resolved


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SERS Spectrum of Pigment Red 122488nm

SERS Spectrum of Razberry Creem (Skin Candy)488nm


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Research Summary

Gel Extraction• Successfully extract and identify

trace amounts• Methodology is system specificSERS substrate• Ag NP synthesis by microwave

reduction yields reliable,reproducible surface

• Stable for at least 5 months

Developing Methods ApplicationsXanthene Dyes• Developing SERS Library• Future Work: MixturesSERS + Phenethylamine• 5 Phenethylamines characterizedSERS of Tattoo Inks• Tattoo Inks are heterogeneous,

present challenge• Work is ongoing

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TLC + SERS

• SERS can improve detection limit beyond visible detection

• Separation and Identification of complex mixtures

SERS of Dye/Drug mixtures

• Engineered Mixtures and Real Samples

Other Areas of Research

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AcknowledgmentsProf. John Lombardi – research advisor (CCNY)

Dr. Marco Leona – research advisor (Metropolitan Museum of Art)

Patrick Buzzini - collaborator (West Virginia University)

Phillip Antoci - collaborator (NYPD Crime Labs)

Current StudentsDane Christie – Undergraduate student (CCNY)

Federica Pozzi - Graduate Student (Metropolitan Museum of Art)Francis Taplin – Graduate student (John Jay)

Peter Decuzzi – Graduate student (John Jay)

Michelle Miranda – Graduate student (John Jay)Kathryn Luppino - Undergraduate student (CCNY)

Yi Pan – Graduate student (CCNY)

Former StudentsDr. Richard Livingstone – Graduate studentLoes Vermeij – Undergraduate student

Elizabeth Sefton – Undergraduate student, WVU

Chara Themistokleous – Undergraduate student

Faiza Anwar – Graduate student

FundingDepartment of Justice (Award Number: 2009-DN-BX-K185)Center for Exploration of Nanostructures in Sensors and Energy Systems (CENSES)

TLC + SERS and Ag NP Gel Extraction

Phenethylamines

Xanthene Dyes

Tattoo Inks

Surface Enhanced Raman Spectroscopy (SERS) and …

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