W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

Unified Organic, Inorganic, and Morphological 

Analysis of Forensic Samples via SEM/TES

W. Bertrand (Randy) Doriese

Quantum Electronics & Photonics Division (686)

Physical Measurement Laboratory

NIST (Boulder)
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

the basic idea...

SEMs are widely used in forensics.

SEM

SEM images from

Forensic Magazine,

Dec., 2008

(Hans Kruesemann) 
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

the basic idea...

A very common technique: energy 

dispersive X-ray spectroscopy 

(SEM/EDS) to analyze elemental 

composition.

SEM

data from Forensic Magazine, Sept., 2012

(Allison C. Murtha and Linxian Wu) 

EDS
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

the basic idea...

A very common technique: energy 

dispersive X-ray spectroscopy 

(SEM/EDS) to analyze elemental 

composition.

SEM

data from Forensic Magazine, Sept., 2012

(Allison C. Murtha and Linxian Wu) 

EDS

Answer the question:

“What is in this sample?”
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

the basic idea...

Our proposal: replace standard 

EDS with NIST high-resolution 

TES X-ray spectrometer (SEM/TES)

• improved X-ray elemental 

analysis of inorganics.

• entirely new X-ray chemicalanalysis method for organics

• retain imaging capability of SEM 

(small spots in context of whole 

sample)

TES SEM
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

the basic idea...

Crime labs are almost always 

operated in a resource-starved 

condition (time; labor).

SEM/TES benefits:

• use same technique on many 

different kinds of 

samples/problems

• as a “first-look” method for 

mixed/unknown samples, may 

eliminate time-consuming, 

serial analysis steps

TES SEM
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

acknowledgements

Co-champions (NIST):

 Kent Irwin, Joel Ullom (Quantum Electronics and Photonics Div., PML)

Terry Jach (Surface and Microanalysis Science Div., MML)

Forensics collaborators:

 Robin Cantor, Ad Hall (Star Cryoelectronics, Santa Fe, NM)

 John Rehr (University of Washington Physics Dept., Seattle, WA)

NIST TES team (Boulder, CO):

Brad Alpert Jim Beall Doug Bennett Colin Fitzgerald

Joe Fowler Gene Hilton Rob Horansky Vince Kotsubo

Luis Miaja-Avila Carl Reintsema Frank Schima Dan Schmidt

Dan Swetz Jens Uhlig Leila Vale

Synchrotron team (NIST / NSLS) (Brookhaven, NY):

Daniel Fischer Cherno Jaye Bruce Ravel Joe Woicik
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

acknowledgements

Special thanks for science discussions:

 Sue Kazanjian, Jason Brewer (FBI Crime Lab, Quantico, VA)

Special thanks for discussion of explosives safety:

 Bill MacCrehan, Greg Gillen, Matt Staymates,

 Tom Bruno, Brian Brass (NIST)
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

outline

1. SEM/EDS vs. SEM/TES.

2. Elemental analysis of inorganics.

3. Chemical analysis of organics.

4. Identification of unknown threat 

powders.

5. Detection of gunshot residue (GSR).
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

silicon-drift detector

The silicon drift detector (SDD) 

is a semiconductor X-ray 

spectrometer.

• impinging X-ray creates 

electron-hole pairs

• size of resulting signal pulse 

proportional to X-ray energy.

(image from Amptek website)
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

silicon-drift detector

The silicon drift detector (SDD) 

is a semiconductor X-ray 

spectrometer.

• is called an “energy 

dispersive spectrometer” 

(EDS) because it uses no 

-dispersive elements 

(gratings, crystals)

(image from Amptek website)
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

SEM/EDS

SEM/EDS uses characteristic 

X-ray lines to identify / quantify 

elements in sample.

(image from Amptek website)

(from “X-ray Data Booklet”)
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

SEM/EDS

SEM/EDS advantages:

• large collecting area

• high QE

• acquire entire spectral ROI 

at once

• fast electronic response

• ubiquitous commercial avail.

• large body of literature on 

spectral interpretation

• little sample prep required

• non-destructive of sample. (image from Amptek website)
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

SEM/EDS vs. SEM/TES

SEM/EDS main disadvantage:

• energy resolution limited to 

~125 eV (FWHM, @ 6 keV)

• by contrast, NIST’s TES 

spectrometer achieves 

E ~ a few eV.
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

microcalorimeter basics

Tbath

temperature

time

C

E

G

C

τ =

X ray (E) thermometer

absorber: 

heat 

capacity 

(C) thermal 

conductance 

(G)
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

transition-edge sensor (TES)

resistance

T

R

R

T

d

d

Tc

temperature

superconducting transition

Tbath

Energy resolution (Johnson & 

thermal fluctuation noise): Best E  low Tc

(~ 100 mK)

 high (~ 75)

 low C (< 1 pJ /K)

k T C

E

2

FWHM

4 B c ~ 2.355

thermometer

absorber: 

heat 

capacity 

(C) thermal 

conductance 

(G)
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

SEM/TES commercialization

Star Cryoelectronics TES array

on a Hitachi SEM
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

SEM/TES commercialization

Star-Cryo TES specs:

• 16-element spectrometer

• E ~ 10–15 eV (FWHM)

• count rates ~ 10 kc/s

Possibly appropriate for 

mobile forensics labs!

recent ad in Microscopy Today
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

continued NIST TES development
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

inorganic example #1: stainless-steel

Ni K

Cr K

Fe K

Fe K

Mn K Cr K

X-ray emission energy (eV)

counts / 2 eV bin

SS-316 ball-shot

StarCryo SEM/TES

 ESEM = 16 keV

EFWHM ~ 17 eV

ID/quantify Mn in the presence of Cr?
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

inorganic example #1: stainless-steel

Ni K

Cr K

Fe K

Fe K

Mn K Cr K

X-ray emission energy (eV)

counts / 2 eV bin

SS-316 ball-shot

StarCryo SEM/TES

 ESEM = 16 keV

EFWHM ~ 17 eV

Forensics: SS-420 (knife blades).
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

inorganic example #2: S / Mo / Pb overlaps

ID/quantify S in presence of Mo (forensics: carbon steels)

Mo L 1,2

S K 1,2

Mo L 1

Pb M 1

Pb M

S K

MoS2 dry lube

NIST SEM/TES

EFWHM ~ 5 eV
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

inorganic example #2: S / Mo / Pb overlaps

co-ID/quantify S and Pb (forensics: copper alloys)

Mo L 1,2

S K 1,2

Mo L 1

Pb M 1

Pb M

S K

MoS2 dry lube

NIST SEM/TES

EFWHM ~ 5 eV
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

inorganic example #3: As content in Pb

Crucial line overlap:

• As K 1(10.544 keV)

• Pb L 1(10.552 keV)

NIST SEM/TES should be able to resolve (no data yet).

image from website of National Park Service

In analysis of Pb bullet fragments, 

As content (typically 1–5 %) can 

ID the Pb alloy.
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

organic chemical analysis

Organic chemicals all contain basically the same 

elements: C, N, O, and then S and some other stuff.

To ID them, you need to know the chemistry.

X-rays: need to measure few-eV shifts in line 

positions/shapes. THIS IS HARD!

Recently demonstrated with NIST TES spectrometer 

installed at the NSLS (synchrotron).
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

chemical-shifts in TES spectra

C (dirt) O

N

C

N

O

scattered beam

Observe two explosives at the 

NSLS synchrotron with TES:

• RDX: major component of 

C4 plastic explosive

• ammonium nitrate (fertilizer; 

can be used to build fertilizer 

bombs)

excite @ 425 eV 

(well above N edge) to simulate 

excitation by SEM.
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

chemical-shifts in TES spectra

zoom in on nitrogen peak 

in each spectrum:

C (dirt) O

N

C

N

O

scattered beam
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

chemical-shifts in TES spectra

RDX is clearly distinguishable 

from NH4NO3.
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

chemical-shifts in TES spectra

NH4NO3 has four resolved 

features that are associated 

with:

• NH4

+

(highly reduced N)

(2)

• NO3

–

(highly oxidized N)

(1, 3, 4)

(feature ID’s from F.D. Vila, et al., 

1 J Phys. Chem. A, 115, 3243-3250 [2011])

2 3

4
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

NIST X-ray chemical database

Generalization of this method will require NIST database of 

C, N, O spectral-emission features.

from F.D. Vila, et al.,

J Phys. Chem. A,

115, 3243-3250 [2011])
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

Terry Jach (Div. 637) and collaborator John Rehr (UW) 

have begun a pilot program to build such a database.

NIST X-ray chemical database

from F.D. Vila, et al.,

J Phys. Chem. A,

115, 3243-3250 [2011])
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

Will combine high-res. spectra from a synchrotron grating 

spectrometer with StoBe and FEFF8 theoretical models.

NIST X-ray chemical database

from F.D. Vila, et al.,

J Phys. Chem. A,

115, 3243-3250 [2011])
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

mixed/unknown threat powders

If not anthrax, what is it?

• Explosive?

• Toxin?

• Baby powder?

• Table salt?

• Wheat flour?

• Several of these together?
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

mixed/unknown threat powders

If not anthrax, what is it?

Presently, methods include:

• FTIR spectroscopy

• PL microscopy

• GC-MS

• LC-MS

• SEM X-ray microanalysis

• Raman spectroscopy

• XRD crystallography
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

SEM/TES for mixed GSR detection?

SEM/EDS is presently used to 

detect primer gunshot residue.

data from Forensic Magazine, Sept., 2012

(Allison C. Murtha and Linxian Wu) 

Key primer materials:

• lead styphnate (initiator)

• barium nitrate (oxidizer)

• antimony sulfide (fuel)
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

SEM/TES for mixed GSR detection?

Organic residue of unburned propellant 

can be detected by LC-MS / GC-MS:

• nitrocellulose

• nitroglycerin

• nitroguanidine

• dinitrotoluene (DNT)

• diphenylamine (DPA)

• ethyl centralite

• resorcinol
W.B. Doriese. Forensics@NIST. Gaithersburg, MD. November 29, 2012 

SEM/EDS v SEM/TES inorganics organics threat powders GSR

conclusions

• SEM/TES is available commercially, but is also 

being further developed and improved by NIST.

• Can provide instant improvement to X-ray 

microanalysis of inorganics.

• Have begun a program to assess X-ray 

microanalysis of organics.

• Mixed organic/inorganic capability could save a lot 

of time and effort.

 doriese@boulder.nist.gov