Standard Guide for Using Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy (SEM/EDS) in Forensic Polymer Examinations

Importancia y uso:

4.1 This guide is intended to advise and assist the analyst in the preparation of polymer samples (for example, paint and tape) for SEM/EDS, the collection of data by SEM/EDS, and the interpretation of images and data resulting from these analyses.

4.2 When polymers are constructed as layered materials, SEM/EDS analysis is conducted on each polymeric layer individually. This analysis can be hindered by a non-discernable layer structure (for example, smear, irregular segregation within the layer system).

4.3 SEM-EDS data can be useful in:

4.3.1 Layer Elucidation—SEM images provide insight into the layer structure of a sample.

4.3.2 Texture Elucidation—SEM images and elemental maps provide insight into the texture (for example, surface topography, distribution of inclusions).

4.3.3 Element Identification—Determination of the elements detected in a sample layer.

4.3.4 Relative Elemental Abundance Determination—An EDS spectrum permits the relative abundance of elements in samples to be compared.

4.4 In the context of a forensic polymer comparison, the evaluation of SEM/EDS results are intended to provide insight into the following forensic tasks:

4.4.1 Comparison of structure, texture, and elemental data.

4.4.2 Support for results from other instruments (for example, the presence of calcium, oxygen, and carbon in the EDS spectrum obtained from discrete particles indicates the presence of calcium carbonate as observed in an infrared spectrum). Refer to Guides E2937 and E3085 for further details.

4.4.3 Significance of results given the presence of certain elements, layer structures, or textures.

Subcomité:

E30.15

Referida por:

E1610-18, E1732-24E01, E3234-20

Volúmen:

14.02

Número ICS:

07.140 (Forensic science), 17.180.30 (Optical measuring instruments), 87.040 (Paints and varnishes)

Palabras clave:

EDS; energy dispersive X-ray spectrometry; paint; polymers; scanning electron microscopy; SEM; tape;