Combining grazing incidence X-rays and micro-diffraction for qualitative phase identification in forensic powdered...

Area of Science:

• Materials Science
• Analytical Chemistry
• Forensic Science

Background:

• Characterizing small samples (milligrams) is typically done with capillary diffraction or microdiffraction.
• Grazing incidence (GI) diffraction methods are used for thin film analysis.
• Analyzing microgram quantities of powder samples presents significant challenges.

Purpose of the Study:

• To develop and evaluate a novel X-ray diffraction technique for analyzing extremely small powder samples (micrograms).
• To improve the intensity of diffraction peaks for trace powder samples.
• To provide an alternative to conventional methods when sample quantity is limited.

Main Methods:

• Utilized standard Bragg-Brentano X-ray powder diffraction geometry.
• Employed grazing incidence X-ray micro-diffraction (GIµXRD) with a micro focusing source.
• Analyzed forensic samples (soils, cosmetics, pyrotechnics, explosives) with incident beam angles from 1 to 5 degrees and sample shaking.

Main Results:

• The combined technique, particularly with a fixed incident beam angle of 3-5 degrees, significantly improved peak intensity compared to conventional Bragg-Brentano methods.
• Different incident angles yielded varying improvements in specific regions of the diffraction patterns.
• Successful analysis of diverse microgram-quantity forensic samples was demonstrated.

Conclusions:

• The novel data acquisition technique, combining Bragg-Brentano and GIµXRD, is effective for analyzing trace powder samples.
• This method offers a powerful alternative for characterizing minute samples in forensic science and other fields like nanomaterials and medicine.
• It potentially reduces the need for sample transport and access to large-scale facilities.