Ion Beam Analysis for Forensic Science. Dr. Melanie J. Bailey Surrey Ion Beam Centre, University of Surrey, UK

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1 Ion Beam Analysis for Forensic Science Fighting Crime with Ion Beams Dr. Melanie J. Bailey Surrey Ion Beam Centre, University of Surrey, UK

2 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

3 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

4 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)

5 Background : IBA in forensics Courtesy of Steve Sugden, Harwell Consulting

6 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)

7 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

8 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

9 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)

10 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 ~ ppm 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 GRR

11 Rutherford Backscattering Spectrometry Energy of ions scattering from nuclear collisions depends on mass and depth Depth profiling with depth resolution <10nm Detection limit around 0.1% Makes PIXE and PIGE quantitative and absolute Courtesy of T. Calligro, C2RMF, France Al Au Ti Pd Ga Spectrum of Ti/AuPd layer on Alumina Substrate

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

13 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

14 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

15 Contents Why use IBA techniques in forensic science? Example 1: Gunshot residues Example 2: Soil analysis Example 3: Glass analysis Complementary IBA / SIMS Example 4: Fingerprints Conclusions

16 The Gunshot Residue Problem in Forensics Gunshot residue (GSR) particles : primer, bullet, bullet jacket, cartridge casing, gun barrel

17 Uniqueness of GSR LGC Forensics (UK) : Classification of gunshot residue into 5 different types using SEM-EDS elemental composition

18 Gunshot Residue in UK Casework

19 SEM-EDSEDS Technique of choice for GSR analysis Imaging of GSR Automated analysis of GSR Cheap

20 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

21 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)

22 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

23 PIXE and EDX spectra Cu K Pb L Sn K 100 Sb K 10 Fe K M J Bailey, K Kirkby and C Jeynes, J. X Ray Spec, accepted Dec 2008, DOI /xrs.1142

24 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)

25 Accurate Quantification of GSR particles by PIXE/RBS M J Bailey and C Jeynes, /j.nimb (2008) Fitted RBS spectrum Fitted PIXE data Fitted depth profile Quantitative analysis possible by PIXE/RBS C substrate GSR particle

26 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.

27 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

28 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

29 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)

30 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

31 Can PIXE be used to identify different Can PIXE be used to identify different provenances (grain types) of quartz?

32 Sample 3: Mixed Sample 1: 2 grain types Pure Quartz Sample 2: Real 1 grain type

33 How reproducible is the technique? Typical PIXE maps from sample 1 Typical PIXE maps from sample 2

34 How reproducible is the technique? Concentra ation (ug/g) grain 1 grain 2 grain 3 grain 4 grain 5 ion (ug/g) Concentrat 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

35 Typical PIXE maps for Sample 3 Mixed (two grain types) Two major classes of map: Either: Or: +Sr, Ba and Rb + luminescence

36 Can we distinguish i i one source from another? (ug/g) Fe Mixed Real Pure Quartz Ca (ug/g)

37 Can we distinguish i i one source from another? (ug/g) Fe Mixed Real Pure Quartz Ca (ug/g)

38 Work in Progress Quartz grains from previous murder investigations will be studied d using PIXE PIGE IBIL Mapping to study the microstructure

39 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

40 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?)

41 PIXE in casework The paper contains many impurities Note in particular S, K, Ba, Pb, Rb

42 PIXE in casework 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 ) S K Ca Ti Mn Fe Cu Zn Ga As Rb Sr Ba Pb Manso et al (Nucl. Instr. Meth. Res. B, 580 (2007), )

43 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

44 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

45 Example 4 : Fingerprint Analysis by SIMS (secondary ion mass spectrometry) Thames Valley Police, Scotland Yard + Steve e Hinder and John Watts University of Surrey

46 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?

47 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)

48 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)

49 Fingerprint i Analysis Using MeV SIMS 10 MeV O4+ TOF SIMS, 4 micron beam Nivea for women Fingerprint H

50 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?

51 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

52 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

53 Thank you