Ion Beam Analysis for Forensic Science - SPIRIT

Ion Beam Analysis for Forensic Science 

Fighting Crime with Ion Beams 

Dr. Melanie J. Bailey 

Surrey Ion Beam Centre, University of Surrey, UK

Contents 

• Why use IBA techniques in forensic science 

• Example 1: Gunshot residues 

• Example 2: Soil analysis 

• Example 3: PIXE in case work 

• Complementary IBA / SIMS 

• Example 4: Fingerprints 

• Conclusions

Contents 







• Conclusions

Background : IBA in forensics 

Industrial Collaborators: 

National Police Improvement Agency, Surrey Police, Scotland Yard, Merseyside Police, 

the Home Office, the Forensic Science Service, LGC Forensics 

• IBA was used in the case of Markov and the poison umbrella in 

1979 

• Only a very small number of academic publications exist on this 

subject 

• IBA has been used only recently in UK casework (by Surrey)

Background : IBA in forensics 

Courtesy of Steve Sugden, Harwell Consulting

Can Ion Beams Be Useful in Forensics 

Industrial Collaborators: 

National Police Improvement Agency, Surrey Police, Scotland Yard, Merseyside Police, 

the Home Office, the Forensic Science Service, LGC Forensics 

• IBA was used in the case of Markov and the poison umbrella in 

1979 

• Only a very small number of academic publications exist on this 

subject 

• IBA has been used only recently in UK casework (by Surrey)

What Do Forensic Analysts Need 

• Trace evidence analysis: establish 

provenance of material (e.g glass, paints, 

fibres) on a suspect or found at crime scene 

• Analysis techniques for trace evidence that 

are 

• Non-destructive 

ti 

• Accurate / reproducible 

• Highly discriminating 

• Need no sample preparation

Ion Beam Analysis 

RBS 

Energy of scattered protons or He give 

light element composition and elemental 

depth profiles 

MeV protons 

or He 

Sample 

PIXE 

Characteristic i X-ray emission 

i 

Simultaneous part-per-million 

detection of trace elements from 

Na to U 

PIGE/NRA 

Nuclear reactions give characteristic 

gamma rays and/or particles from light 

nuclei (e.g. Li, B, F) 

IBIL 

Ion beam induced 

luminescence

Particle Induced X-ray Emission 

•Analogous to SEM-EDX EDX but using MeV protons or He 

•Information is from femtograms of material 

•Imaging resolution determined by beam size 

•Fully quantitative and absolute 

Courtesy of T. Calligro, C2RMF, France 

•Detection of Na to U 

•ppm sensitivity 

Intensit ty (log scale e) 

Mo 

Si 

Ca 

Fe 

Cu 

Se 

As 

Mo 

X Ray Energy (KeV)

Particle Induced Gamma-ray Emission 

• MeV protons can tunnel through the Coulomb barrier 

of light nuclei to induce gamma-emitting g nuclear 

reactions 

• Gamma energy is characteristic of specific isotopes 

• Detection limits ~ 10-100ppm 

• Useful for light elements: Al, F, Li, B, Na, Mg 

• Sharp resonances in the excitation function can be 

used for depth profiling 

^3 f:\pc_users\jpn\971118\490001g4._ : Tourmaline std: GRR573 

^2 

F 

F 

Li 

B Al Al 

Na 

^1 

^0 

Tourmaline standard 

GRR573 

100 300 500 700 900 1100 1300 1500 1700

Rutherford Backscattering Spectrometry 

• Energy of ions scattering from nuclear collisions 

depends on mass and depth 

• Depth profiling with depth resolution

Ion Beam Induced Luminescence 

• Analogous to cathodoluminescence on SEM (CL) 

• Visible light emitted under ion impact 

• Yields chemical information : 

– Impurities 

– Structural defects 

– Valence states 

Malquvist et al: NIMB 109/110 (1996) 337-233 

Courtesy of S. Calusi, INFN Firenze, Florence, Italy

Why Use Ion Beams in Forensics 

• Analysis does not destroy the samples 

• Very high sensitivity to trace elements 

• Fully quantitative and absolute 

• Analysis can take place in air or in vacuum 

• Can produce elemental maps on a sub 

micron scale 

• Most samples do not need any preparation 

treatments prior to analysis

What Do Forensic Analysts Need 

• Comparison of particles found on suspect with 

particles found at crime scene 

• Analysis techniques es for trace evidence such 

as glass, paints, fibres, soils that are 

• Non-destructive 

• Accurate / reproducible 

• Highly discriminating 

• Need no sample preparation 

a

Contents 




• Example 3: Glass analysis 



• Conclusions

The Gunshot Residue Problem in Forensics 

Gunshot residue (GSR) particles : 

primer, bullet, bullet jacket, 

cartridge casing, gun barrel

Uniqueness of GSR 

LGC Forensics (UK) : 

Classification of 

gunshot residue into 5 

different types using 

SEM-EDS elemental 

composition

Gunshot Residue in UK Casework

SEM-EDSEDS 

• Technique of choice for GSR analysis 

• Imaging of GSR 

• Automated analysis of GSR 

• Cheap

PIXE and SEM-EDS EDS for GSR Analysis 

Residue No. of GSR Firearm Ammunition 

Reference particles 

studied 

Residue 1 12 Ruger Old Army 45 

Pistol 

Residue 2 8 Franchi 12 bone 

Semi Automatic 

Shotgun 

Pyrodex powder 

and Perdesol bullet 

Rottweil 12 cal 

70mm Dynamite 

Nobel 

Residue 3 11 Marlin 357 Gallery 

Magtech 357 

Rifle 

Cowboy Action 

Loads 

Residue 4 8 Parker Hale Rifle Radwell Green 

7.62mm, 155gr 

Samples were collected on an SEM stub with a high purity C sticky pad

SEM-EDS results 

K 

Cu 

S 

Fe 

•Small differences in K, Cu, S and Fe 

•All detected close to the detection limit (at%) 

•Non-quantitative technique 

F ll i t th b d t f f i 

•Fall into the same broad category as far as forensics 

providers are concerned (Pb:Ba:Sb)

PIXE 

2.5 MeV protons, SiLi 50mm 2 detector with 130um Be filter 

• Particles studied by EDS were located using a Cu finder grid 

• Backscattered particle image and Pb signal was used to image particles 

• 10 minute point spectra (on average) were recorded 

d 

BSE image analogue

PIXE and EDX spectra 

100000 

Cu K 

Pb L 

10000 

1000 

Sn K 

100 

Sb K 

10 

Fe K 

1 

0 500 1000 1500 2000 2500 3000 

M J Bailey, K Kirkby and C Jeynes, J. X Ray Spec, accepted Dec 2008, DOI 

10.1002/xrs.1142

PIXE 

K Cl Ca Ni Sn 

•PIXE detects additional differences in Ni, Cl, Ca, Zn and Sn which 

are not detected by EDS 

•These differences are well above the detection limit (at% cf ppm)

Accurate Quantification of GSR particles by PIXE/RBS 

M J Bailey and C Jeynes, 10.1016/j.nimb.2009.03.031 (2008) 

• Fitted RBS spectrum 

• Fitted PIXE data 

• Fitted depth profile 

• Quantitative analysis 

possible by PIXE/RBS 

C substrate 

GSR 

particle

Work in Progress.... 

• Round robin project with LGC Forensics and police forces from 

across the UK to characterise GSR from different sources 

• PIXE will be used to determine to what extent GSR can be further 

sub-categorised.

Contents 







• Conclusions

Quartz Grain Texture Analysis 

R Morgan and P Bull, University of Oxford / Jill Dando Institute for Crime Science 

• Frequently used in UK casework 

• Quartz grains used to provenance soil particles 

recovered from forensic investigations 

• Texture of the quartz is studied by SEM 

• Different quartz grains have different textures 

depending on: 

• the parent rock 

• subsequent processes

Quartz Grain Texture Analysis 

Examples.... 

Grain type I 

“Well rounded grain with impact features (caused 

by river transportation) and subsequent grain 

surface solution (caused by soil acids 

following deposition)” 

Grain type II 

“Very angular grain with no edge abrasion 

(derived from a rock comprising of angular 

grains) with crystal growths on the surface of 

the grain (diagenetic features formed when 

the nearby sandstone had been turned into 

rock millions of years ago)”

Why use PIXE 

• Need an independent technique to verify conclusions 

• PIXE gives completely independent information to quartz 

texture t analysis (elemental l cf topographical) 

• PIXE is more sensitive to trace elements than SEM-EDX 

and mapping is quicker

Can PIXE be used to identify different 

Can PIXE be used to identify different 

provenances (grain types) of quartz

Sample 3: 

“Mixed” Sample 1: 

2 grain types 

“Pure” 

Quartz 

Sample 2: 

“Real” 

1 grain type

How reproducible is the technique 

Typical PIXE maps from sample 1 Typical PIXE maps from sample 2

How reproducible is the technique 

1000000 

1000000 

100000 

100000 

Concentra ation (ug/g) 

10000 

1000 

100 

10 

grain 1 

grain 2 

grain 3 

grain 4 

grain 5 

ion (ug/g) 

Concentrat 

10000 

1000 

100 

10 

grain 1 

grain 2 

grain 3 

grain 4 

grain 5 

grain 6 

grain 7 

grain 8 

grain 9 

grain 10 

1 

Si P S Cl K Ca Ti Cr Mn Fe Cu Zn Rb Sr Ba 

1 

Si P S Cl K Ca Ti Cr Mn Fe Cu Zn Rb Sr Ba Zr 

Sample 1 Sample 2 

• There is a clear distinction between sample 1 and 

sample 2 

• The grain to grain variability is demonstrated

Typical PIXE maps for Sample 3 “Mixed” (two grain types) 

Two major classes of map: 

Either: 

Or: 

+Sr, Ba and Rb 

+ luminescence

Can we distinguish i i one source from another 

100000 

10000 

(ug/g) 

Fe 

1000 

100 

Mixed 

Real 

Pure Quartz 

10 

1 

1 10 100 1000 10000 100000 

Ca (ug/g)

Can we distinguish i i one source from another 

100000 

10000 

(ug/g) 

Fe 

1000 

100 

Mixed 

Real 

Pure Quartz 

10 

1 

1 10 100 1000 10000 100000 

Ca (ug/g)

Work in Progress 

• Quartz grains from previous murder investigations will be studied 

d 

using 

– PIXE 

– PIGE 

– IBIL 

– Mapping to study the microstructure

Contents 







• Conclusions

PIXE in casework 

• June 2008, Surrey IBC 

• Document from a murder investigation 

• External beam PIXE used to establish the age of the document 

• i.e. was it current (>2006) or old (c1960)


• The paper 

contains many 

impurities 

• Note in 

particular S, K, 

Ba, Pb, Rb


• A previous study of newspaper 

from three different dates by 

XRF 

• Earlier paper contained a 

greater concentration of 

impurities 

• In modern day paper, Pb, Ba, 

S, K and Rb should not be 

present 

Concentration (μg g -1 ) 

1919 

100000 

1941 

2005 

10000 

1000 

100 

10 

1 

S K Ca Ti Mn Fe Cu Zn Ga As Rb Sr Ba Pb 

Manso et al (Nucl. Instr. Meth. Res. B, 580 (2007), 732-734)

Contents 







• Conclusions

Secondary Ion Mass Spectrometry 

• Primary ion beam (KeV or MeV) is used to sputter target material 

• Secondary ions are analysed in mass spectrometer 

• Surface mass spectrometry 

• High sensitivity– ppb 

• Molecular specificity 

• Quantification difficult

Example 4 : Fingerprint Analysis by SIMS (secondary 

ion mass spectrometry) 

Thames Valley Police, Scotland Yard + Steve e Hinder and John Watts – University of Surrey

SIMS Imaging of Fingerprints 

i 

• Fingerprints are still used in police 

investigations 

• To back up DNA evidence 

• Where it cannot be used 

• Can we obtain chemical information from 

fingerprints 

• Smoker 

• Diet 

• Cosmetics

Can We Detect Moisturiser i in Fingerprints i Nivea for Men : Moisturiser 

Glycerin; sugar-alcohol of varied use 

Na Laureth sulphate; detergent/surfactant used widely in personal care products. 

Tocopheryl acetate; vitamin E acetate used in skin creams 

Bisabolol; fragrance, has perceived skin care properties. 

PEG-7 glyceryl cocoate; fatty acid mixture from coconuts 

Xanthan Gum; polysaccharide chain used as rheology modifier 

Benzophenone; UV blocker 

Phenoxyethanol; range of properties, often found in skin creams 

Parabens; Methyl, Ethyl, Propyl & Butyl : used as an antifungal preservative. 

Na carbomer. 

Na methyl cocoyl taurate. 

Farnesol; perfume/flavouring agent 

Imaged molecule : polyethylene terephthalate (PET) 

Substrate : poly(vinylndene difluoride) (PVdF)

C 3 F 4 H + 

Green = fingerprint 

149 m/z 

C + 

3 F 5 H 

Blue = PVdF topcoat 

197 m/z 

Substrate (PVdF) Moisturiser (PET)

Fingerprint i Analysis Using MeV SIMS 

• 10 MeV O4+ TOF SIMS, 4 micron beam 

• Nivea for women 

Fingerprint 

600 

H + 500 

300 

400 

200 

100 

0 

0 100 200 300 400 500

Future Prospects 

• MeV SIMS : in air analyses 

• Will allow larger molecular fragments to be imaged – i.e. chemical 

information from fingerprints 

• Can we develop fingerprints on difficult surfaces 

– Patterned surfaces : e.g. money 

– Reagent development issues : covert analyses 

• Can we use SIMS/MeV SIMS to detect the sequencing of fingerprint 

/i ink

Conclusions 

• PIXE / PIGE / RBS / IBIL can be carried out simultaneously and are 

highly discriminating compared with other non-destructive 

techniques. 

• Work is in progress to establish the use of these techniques in police 

casework 

• SIMS / MeV SIMS are useful techniques for new types of fingerprint 

analysis

Ak Acknowledgements ld 

Surrey IBC Staff 

Chris Jeynes 

Karen Kirkby 

Geoff Grime 

Matt Christopher 

Jill Dando Institute for Crime Science 

Ruth Morgan 

NPIA and Surrey Police 

John Armstrong 

Martin Hanly 

Scotland Yard 

Gary Pugh 

LGC Forensics 

Chris Moynehan 

Oxford University 

Peter Bull

Thank you

Ion Beam Analysis for Forensic Science - SPIRIT

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?