NCJ Number
218775
Date Published
October 2002
Length
16 pages
Annotation
This article provides a review of methods for scanning electron microscopy in forensic paint examinations.
Abstract
Following a brief bibliography and glossary, the article considers the significance and use of the scanning electron microscope, which can be used to define and compare the layer structure of multilayered samples, the structure of individual layers, the composition of individual layers, and the elemental composition of individual particle compounds within paints and coatings. Procedures for sample handling are enumerated followed by a discussion of sample preparation, which notes that samples should first be examined with a stereomicroscope for size, structure, and overall homogeneity measurements. Moreover, it is fairly typical for extraneous materials to be present on the surface of a specimen submitted for analysis. These extraneous materials can be noted and removed during the stereomicroscopic examination. Methods of attaching a sample to a scanning electron microscope mount are described followed by a demonstration of how to expose the internal structure of the sample for analysis. The analytical procedures for scanning electron microscopy are outlined and include notes on instrument calibration, structural imaging, and the selection of scanning electron microscopy/energy dispersive X-ray spectrometry operating conditions. This section of the article also discusses qualitative analysis, comparisons of a small particle to a bulk sample, and how to analyze smears and organic layers. Notes are offered on the assessment of results during analysis and on the interpretation of scanning electron microscopy/energy dispersive X-ray spectrometry data. The final section of the article discusses the procedures for documentation. It is noted that the method employed depends on the sample size, sample suitability, and laboratory equipment. References