Forensics

Raman and LIBS (Laser Induced Breakdown Spectroscopy) analyses methods are considered to be the most modern and efficient methods of obtaining conclusive microscopic sample images from trace evidence.
The SPE-f metal.ID+raman.ID offers many advantages over similiar products because it combines spectroscopic methods in one robust machine while omitting sample transference issues, speeding up analysis time and ensuring quality results.

The Raman Spectroscopic component of the unit determines the molecular composition of a sample while the LIBS component simultaneously performs multi-elemental composition analysis. The ability to perform both analyses on one sample offers quick micro particle sample determination especially useful in forensic science.
Match an array of specimens including soils, unconsolidated sediments, dusts, powders, paint chips, glass and other particulate materials to their origin with unprecedented certainty.

SPE applications for a forensic examiner

RAMAN+LIBS COMBINED SPECTROSCOPY

Forensic Paint Analysis

Loose or transferred paint materials such as paint chips and flakes are often found at crime scenes and offer critical evidence for investigations. Paint origin can be determined or matched to different materials using industrial paint procedure analyses.

Paint chip samples, for example, can lead to the exact make and model of the car from which they originated. Combination spectroscopy can be utilized to piece together an entire crime scene from sparse debris.

Paint is a combination of organic binders, polymers and additives such as organic or inorganic colors and sometimes even effect pigments. Due to the painting process, samples are made up of multiple layers of different materials and colors. Paint is an ideal candidate for the SPE-f raman.ID+metal.ID combination unit for combined Raman and LIBS differentiation and identification analyses because of its multi-material composition and structure.

Pigments, inorganic colors and cations used in dyes and colors have distinctive LIBS spectra. LIBS laser ablation is equipped to accurately analyze these kinds of multi-layer samples and provide pragmatic origin clues. Raman spectroscopy can further identify and measure each organic layer, color and binder material separately using a confocal setup.

Sample: Paint Chips

The paint chip spectra above, for example, indicated a mixture of Titanium Dioxide with an organic backbone of Polyester when analyzed using Raman signals. Phthalocyanine Blue, a widely used pigment for creating the color blue, was identified in other areas of the sample and emitted substantial Raman signals within 30 seconds of exposure time. The single shot LIBS spectra (1sec/shot) revealed Titanium and Copper elements as well.

This paint chip example demonstrates the advantages of using combined and complementary spectroscopic methods for unprecedented material discrimination. The SPE, in contrast to other systems, requires minimal sample preparation and uses laser ablation, which prevents most sample damage. As a result, the SPE is a next generation unit providing more material information, requiring less manpower, cutting analysis time and all of these features at a fraction of the price.

(Several hundred paint chips can be identified in just 30 minutes using automated (Raman and LIBS) scan functions. Statistical data interpretation has significantly improved a forensic examiner’s ability to discriminate different samples and accurately identify substances.)

The rap.ID SPE-f metal.ID system addresses other application areas of paint examinations that are not addressed with comparative LIBS techniques. Color is the most discriminating characteristic in paint samples, making the optical platform a good tool for evaluating this aspect in situ. rap.ID Particle Systems technology enables the user to discern color beyond optical microscopy, conduct organic (Raman) and inorganic (LIBS) layer-by-layer evaluation discrimination and simultaneously compare
these search results to a well developed matrices database including various binders, fillers, pigments and other components. No other current technology has all these capabilities in one robust unit.

References:

Erin McInteea, Emilie Viglinoa, Caitlin Rinkea, Stephanie Kumora, Liqiang Nib, and Michael E. Sigmana, “Comparative analysis of automotive paints by laser induced breakdown spectroscopy and nonparametric permutation tests”, 2010 Spectrochimica Acta Part B: Atomic Spectroscopy doi:10.1016/j.sab.2010.04.021

Romain Bruder “An example of the complementarity of laser-induced breakdown spectroscopy and Raman microscopy for wall painting pigments analysis”.2007; Journal of Raman Spectroscopy

Material Science

Geology Raman Spectroscopy and Laser Induced Breakdown Spectroscopy (LIBS) are considered revolutionary methods because of their potential to deliver complete images of microscopic samples such soil or other geological samples.

Elemental information reveals material origin, the presence of ores and clues to geological events such as volcanic eruptions from sedimentary layers. Molecular/ vibration Raman information reveals either the presence of organic carbon or the chemical structure of the sample.

Raman and LIBS measure identical areas of micro samples using laser beams. Microscopic images, including shape analysis, are produced and documented for each micro sample. The SPE-f metal.ID + raman.ID combines spectroscopic methods and image analysis technology and yet is still small and robust enough to take into the field, making it an invaluable tool for geoscientists.

LIBS delivers multi-elemental composition analysis whereas Raman yields information about the molecular composition. Spectroscopic combination analyses, in one unit, deliver a unique tool for quick micro-particle sample determination especially useful in geological applications.

Exploration & Geological Science Through Soil Investigation
LIBS/ Raman combined spectroscopy were used in exploratory studies to assess prominent molecular vibration peaks. Raman spectra illustrated that different soils show a close relationship to the amount of organic carbon present. The integrated SPE-f raman.ID+metal.ID system facilitates elemental analysis of heterogeneous environmental and biological matrices by reducing sample preparation and analysis times. It can also provide semi-quantitative results on a regular basis and quantitative results in particular cases.

Quick debris detection and identification makes the technology exceptionally useful in geological applications. Hundreds of separate soil samples can be identified in just 30 minutes using automated (Raman and LIBS) scan functions. Statistical data interpretation has significantly improved a forensic examiner’s ability to discriminate different soil samples and to specifically and accurately identify substances.

Sediment Core Scanning
Sediment cores are collected from hard to reach locations such as oceans, enclosed seas and large lakes. These materials reveal records of past processes such as climate change or extreme events such as floods, storms and volcanic incidents. Typically, Micro XRF X-ray core scanners are used to scan these cores with a resolution of 200 µm. The SPE-f raman.ID+metal.ID unit, however, can scan a core with a resolution as small as 20 µm (14 hours per meter) with virtually no damage to the sample. Additional information from the vibration spectroscopy reveals organic, carbon or chemical core structure material.

Sample: Geology-Soil

Combination Raman/LIBS spectroscopy coupled with a built-in database significantly increasing the value to forensic soil examination. The system automatically separates different size fractions and applies automated size morphology and chemistry analyses against the built-in database. Raman combination is also a tremendous advantageous here as well due to the organic materials (i.e. pesticides, treatments, carbonaceous materials, etc.) that are inherent to top layers of soil, which are most commonly analysed, in forensic casework.

Application:

Archeology/Anthropology: determine colors, clay mixtures or soil origin immediately and in the field.
Geology / Mineralogy: use a highly robust mobile system in the field to explore and detect minerals and trace elements.

Forensic Glass Analysis
Glass samples are often found on crime scenes, and therefore quick and reliable glass origin determination is a standard task in forensic laboratories.

A Refractive Index (RI) typically performs glass fragment type identification but, unfortunately, RI data often overlaps itself, and therefore additional information is required for glass fragment origin determination.

In contrast, SPE-f metal.ID (LIBS) spectroscopy quickly determines elemental composition leading to glass origin determination. LIBS is able to detect lighter elements such as Sodium and Boron that traditional SEM-EDX analysis cannot detect. The SPE obtains unique chemical fingerprints from the glass samples using minimal ablation preserving sample integrity.

Additional integrated Raman spectroscopy analysis offers much higher discrimination and match certainty. Glass frequently transmits a relatively broad Raman spectrum due to color additives mixed into glass or organic protective layers used in car glass to prevent it from breaking. However, even these types of glass samples can still be easily and quickly identified with the SPE-f raman.ID+metal.ID unit.
A combination of both spectroscopic methods delivers a very high level of discrimination between several fragments and glass samples.

Yet another added benefit is the system’s ability to analyze hundreds of small glass fragmentsusing automated (Raman and LIBS) scan functions in just 30 minutes. Statistical data interpretation has significantly improved a forensic examiner’s ability to discriminate different samples and to specifically and accurately identify substances.

Sample: Glass

The identification of a glass particle since.

LIBS provides a quick, accurate, and cost effective solution for forensic glass examination.

The Single Particle Explorer System’s foremost asset is its ability to analyze large number of particles quickly and automatically. This feature allows an examiner to gain an overall view of each particle within several minutes. Sample preparation is minimal in general and GSR samples require even less preparation. A swab sample can be scanned directly.

The presence of small ammunition particles is an indicator that a firearm has been used. The ammunition particles can be searched in order to identify the manufacturer and whether the particles contain the elements Barium (Ba), Lead (Pb) and Antimony (Sb.) Normally, SEM-EDX and imaging analysis are used to identify the presence of these particles.

Example of the Analysis:
The SPE-f metal.ID unit can scan an area as small as 1x1 cm of a swab sample. For example, integrated image analysis found 1,298 individual particles within such a sample in just 2 minutes. The automated particle id then measured 10% of the identified particles (~100.) The majority of them were identified as gun shot residue in just one second because, among other things, they emitted a spectra of Pb and Ba . The entire analysis time, including mounting the swab into the system, took just 4 minutes. The system’s 4-fold automatic sample changer enables an analyst to measure 4 samples in just 20 minutes.

The SPE-f metal.ID is an ideal tool for forensic examiners because it is capable of quickly identifying large number of samples such as gun shot residue using virtually no sample preparation.

GSR Sample

References

VALET, O., LANKERS, M., (2008), Higher Yield and Quality through Particle Identification, Journal of the IEST, October 2008

VALET, O., (2006), Application: Safe and Simple Component Cleanliness, rap.ID Particle Systems GmbH

LANKERS, M., (2003), Higher Productivity through Particle Identification - Manufacturing of Parenterals, Annual Meeting der PDA 2003

VALET, O., (2002), Made to Measure, Cleanroom Technology, Polygon Media

LANKERS, M., (2002), Determining particle composition: Consider the path to the source, Cleanrooms, PennWell