M. Falke, et al.

From Nanoparticles to Single Atoms, EDS of Electron Transparent Samples

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Presenters

Dr. Meiken Falke

Product Manager EDS/TEM, Bruker Nano Analytics, Berlin, Germany

Dr. Igor Nemeth

Application Scientist,Bruker Nano Analytics, Berlin, Germany

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M. Falke, et al.

From Nanoparticles to Single Atoms, EDS of Electron Transparent Samples

Outline

Nanoparticles / Nanoobjects – what is this about

SDD Technology

Examples of nanoanalysis using various combinations of EDS and EM

Conclusions: options to characterize NP, their distribution and environment

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SEM

nanoclay in polymer1 nm

Cs-corr. STEM

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STEM

300 nmSENi C

T-SEM

CNT+catalyst NP CNT+catalyst NP

Cs-corr.STEM

Core-shell NPCell+NP

Single atom

From Nanoparticles to Single Atoms, EDS of Electron Transparent Samples

wikipedia

Ω ∼ Asurf / r2 [sr]

Detector Types for SEM/T-SEM andTEM/STEM andSolid Angle for X-Ray collection

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Spezial Systems with radial symmetry:FEI 0.9 sr (4 x 30 mm2)FEI High res. PP 0.7 sr (4 x 30 mm2)FlatQuad 1.2 sr (4 x 15 mm²)

FEI

Single/multiple stand alone Systems:ΩEDS-SEM ~ 0.01 – 0.05 srΩEDS-S/TEM ~ 0.1 – 0.4 – 0.7 srNion+Bruker ~ 0.7sr (0,91sr)

d Ω

!

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Geometric limits (TEM/STEM)

solidangleTOATOA

TOA

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Inverse solid angle! … how much of the surroundings do we see?A small collimator opening is better to avoid system peaks.

Solid angle by Nestor Zaluzec: http://tpm.amc.anl.gov/NJZTools/XEDSSolidAngle.html

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Detector quantum efficiency and Windows of in situ reaction cells

Moxtek window:Polymer + Si support grid

Contact layer

Si detector crystal

Si dead layer

gas

Detector w/wo window

+ reaction speciessticking to cell walls

Window ofreaction cell

Lines above 50 keV can be used

Powder of pure Dy2InSb07

Sample courtesy: Maria Bacia, CNRS Grenoble;Data courtesy: Philippe Lasson, Synergie 4

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In situ: Comparing EDS spectra at RT, 800, and 900 oC

• Noise mostly at low E, from radiation

• The window material of the SDD blocks 99% of the light

• Yes, we can do spectrum imaging up to ~ 800 oC

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---- RT ---- 800 oC---- 900 oC

SDD

Jane Y. Howe (ORNL), Christianne Beekman (Florida State Uni)Bruker 30mm2 SDD on SEM (Zeiss Merlin)

500nmBF

PS

Ag

C O

NOs

EDS for Life ScienceYeast Cell: Element mapping ofprotein labels and light and heavy elements

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30 mm2, 0.12 sr (Standard EDS); Conventional STEM

Iron intake in food vacuole, since the parasite is digesting

hemoglobin

science.nationalgoegraphic.com science.nationalgoegraphic.com

Anopheles mosquito

The parasite multiplies by destroying red blood cells.

Data courtesy: C. Biot and C. Slomianny, Laboratory of Cell Physiology, University of Lille, France; STEM CM300

EDS for Life Science at 0.1srMalaria Parasite: Plasmodium Falcip. in erythrocyte treated with Chloroquine

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Malaria can betreated e.g.by

Chloroquine

Peak Separation

measured

Os

P

Os+P+…

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Peak Separation

measured

Os

P

Os+P+…

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Ix = NA σA ωA (Ω/4π) ε Ne = nA t σA ωA (Ω/4π) ε Ne

Ix number of X-ray photons in a characteristic peak of species A

N number of atoms per unit volumen t number of atoms per unit area times thickness

σ ionization cross section (Casnati et al., 1982, Bote et al., 2009)ω fluorescence yield (Hubbell et al., 1994, Krause, 1979)Ω/4π solid angle / geometrical collection efficiencyε detection quantum efficiencyNe number of incident electrons

+ absorption

TEM EDS Quantification;

R. Egerton 1994, line intensity for a particular element line / transition

CB

CA=kAB

IA

IB kAB can be determined experimentally or theoreticallyCliff andLorimer:

Zeta-Factor

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• For testing we used Si3N4a single layer (30nm) as the sample a double layer (60nm) as the standard

• STEM probe current: 344pA

30nm 60nm

Si3N4

CL: Si at% N at% d nmSi3N4_expected 42,86 57,14Si3N4_60nm_st. 42,86 57,14Si3N4_30nm 43,84 56,16Zeta:Si3N4_30nmZeta 41,96 58,04 30

• Zeta Method: M. Watanabe J. ofMicr. 2005

• Further tests with Al2O3, TiO2, GaAs• Very sensitive to

- probe current and- thickness variations

TEM EDS QuantificationZeta vs CL

Pt shell not closed due to fabrication procedure

Data courtesy: Dogan Ozkaya,Johnson Matthey Technology Center.Jeol STEM

EDS for Catalysis, QuantificationPt-Pd Core Shell Particles

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mass%, 30 mm2, 0.12 sr (Standard EDS); Cs-corr. STEM

Simultaneous EDXS and EELS from a single Si atom

ADF image of a defect in monolayer graphene recorded after spectra were acquired. Arrow points to a tracked Si impurity atom.

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Nion UltraSTEM100, 60 keV, Daresbury UK. Bruker SDD EDXS, Gatan Enfina EELS

EDXS and EELS data recorded simultaneously.

Ip = 190 pA, 0.09sr, 224 s acquisition;

Thereof ~10s beam close to the atom.

Tracking movie of 1 Si atom on graphene as recorded during EDS spectrum acquisition

E ELS

ED(X)S

30mm2, SLEW; CFEG, Cs corrected STEM

Single atom spectra

T. C. Lovejoy et al., APL 100, 154101 (2012)

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224s single Si atom spectrumC115 counts

Si51 counts

Grid?Cu23 counts

C+Pt374 counts

Pt206

Cu208 Pt

Fe45

Co48

245s single Pt atom spectrum

Grid?Polepiece?

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100mm2

EDS with 100 mm2 windowlessoval detector area; Nion UltraSTEM, Cs-corrected, high brightness source

EDXS at ~0.7 sr … flat, collimated

100mm2 / (10.5mm)2 = 0.91sr

TOA: 13.4°

Wikipedia: solid angle

Identifying atoms by EDXS, one-by-one

HAADF image of meteorite nanodiamondwith impurities > not as ideal as graphene! Nion UltraSTEM200, 60 keV,Bruker Quantax XFlash UHV windowless SDD.courtesy Rhonda Stroud, NRL, M&M (2015)R. M. Stroud et al., APL 108, 163101 (2016)

EDXS of atom 1,9.4 sec, 74 Si

counts

EDXS of atom 2,8 sec, 33 S counts*

*tracking area was ~2x larger for S, hence the lower counts. Cu is a system peak due to sample holder & polepiece caps.

E / keV E / keV

100 mm2 SDD at 10.5 mm => 0.7 sr

Si

CuCu

S

x 0.001cps/eV

Polymer composite containing organo clay

2 µm

XFlash QUAD vs Single detectorin SEM:

XFlash Flat QUAD detector Single 30mm2 XFlash

Sample courtesy by Dalto et al., Universidade Federal do Rio de Janeiro, Data courtesy T. Salge (Bruker / NHM, London);

3 kV, 220pA, 10 kcps, 320 s, 1024x768 pixel

3 kV, 220pA, 0.8 kcps, 320 s, 1024x768 pixelShadow effects due to rough surface

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Flat Quad XFlash 5060

N. J. Zaluzec, Detector solid angle Formulas for use in EDS, Microsc. Microanal., 15 (2009) 93

http://tpm.amc.anl.gov/NJZTools/XEDSSolidAngle.html

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Flat Quad XFlash 5060

max solid angle atd = 2.5mm:Ω > 1.1 sr

dΩ

Solid angle and OCR vs distance d

Cu, 1nA, 5kV

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T-SEM-EDX of NPTypical Overview

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Analysis: T. Salge (Bruker/NHM)

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TSEM-EDX of fluorescent core shell NP; Silica nanoparticles coated with Alexa® dye

XFlash FlatQUAD, 5 kV, 520 pA , 22.5 kcps, 250x250 pixel, 2 nm pixel size, 377 s

K. Natte, T. Behnke, G. Orts-Gil, C. Würth, J. F. Friedrich, W. Österle and U. Resch-Genger, J Nanopart Res, 2012, 14, 680;

Analysis: T. Salge; Hitachi SEM

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T-SEM-EDX of SiO2 NP;PA: Classification, Statistics

„bulk“ NP

„hollow“ NP

unclassified NPSDD10 mm2

Flat QUAD

Acq time (s per NP) 120 2

ICR (kcps) 0.3 ≥20

Solid angle (sr) 0.01 1

NP identified 25 127

3nmAnalysis: T. Salge (Bruker/NHM); Hitachi SEM

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EDS; Characterization of Nano-Objects;Possible Steps

SEM/T-SEM > Overview / embedding/ statistics on mm-nm scale> Using annular detector> Combine with other analysistechniques (TKD, µXRF, µCT)

Standard / Cs-corrected STEM + Standard EDS

> Q-Mapping in at% and nm formaterials and life science

Cs-corr. STEM + high Ω EDS> Single atoms

> in situ (liquids, gases, temp.)

Q&A

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