Characterisation of 0.22 Caliber Rimfire Gunshot Residues by Secondary Ion Mass Spectrometry (SIMS) (CAT#: STEM-ST-1734-CJ)

Secondary Ion Mass Spectrometry (SIMS) is a technique used to analyze the composition of solid surfaces and thin films by sputtering the surface of the specimen with a focused primary ion beam and collecting and analyzing ejected secondary ions. The mass/charge ratios of these secondary ions are measured with a mass spectrometer to determine the elemental, isotopic, or molecular composition of the surface to a depth of 1 to 2 nm.

Forensic Science

1. Sample preparation: The sample is prepared by cleaning it to remove any contaminants that could interfere with the analysis. The sample may also be coated with a thin layer of conductive material to prevent charging during analysis.
2. Primary ion bombardment: The sample is bombarded with a beam of high-energy primary ions, typically from an ion gun. The primary ions interact with the atoms on the surface of the sample, causing the ejection of secondary ions, neutrals, and electrons.
3. Secondary ion extraction: The secondary ions are extracted from the sample surface using a high voltage electric field. The extracted ions are accelerated towards the mass spectrometer.
4.Mass separation: The ions are separated by their mass-to-charge ratio (m/z) using a mass spectrometer. The ions are then detected by an ion detector, which measures their abundance.
5. Data analysis: The data is analyzed to determine the elemental and isotopic composition, as well as the chemical structure and molecular fragmentation patterns of the sample. This information can be used to identify the material and understand its properties and behavior.

• Sample: Solid thin layer; Flat surface material; Powder; Metals; Semiconductors and Insulators & More
• Equipment: Dynamic Secondary Ion Mass Spectrometry (D-SIMS) instruments

1. Surveys of all masses on material surfaces; these may include single ions (positive or negative), individual isotopes, and molecular compounds.
2. Elemental and chemical mapping on a sub-micron scale.
3. High mass resolution, to distinguish species of similar nominal mass (mass resolution is at least 0.00x amu).
4. High sensitivity for trace elements or compounds, on the order of ppm to ppb for most species;.
5. Surface analysis of insulating and conducting samples.
6. Depth profiling (in the near surface environment, on the order of individual atomic layers to 10s of nanometers).
7. Non-destructive analysis.
8. Retrospective analysis, for post-data acquisition analysis and interpretation of stored images and spectra.