Date of Award

June 2018

Degree Name

Master of Science (MS)

Department

Chemistry

Advisor(s)

Timothy M. Korter

Keywords

gunshot residue, low-frequency Raman spectroscopy, nitroguanidine, solid-state density functional theory, Terahertz spectroscopy

Subject Categories

Physical Sciences and Mathematics

Abstract

Low-frequency spectroscopic techniques, including terahertz time-domain spectroscopy and THz-Raman spectroscopy, are used in conjunction with solid-state density functional theory simulations to investigate the vibrational modes of the explosive propellant nitroguanidine and three gunshot residues. Terahertz spectroscopy and low-frequency Raman spectroscopy are used to probe these small organic crystalline systems because the low-frequency (sub-200 cm-1) spectra for these systems are either, in the case of terahertz, not yet published in the spectral range obtained in this work, or in the case of Raman, not focused on in the literature. Low-frequency spectra and the corresponding solid-state density functional theory simulations can provide information on the vibrations and torsions within the crystal that are unique to the system and can be used to detect and identify these organics. Since all the organics studied in this work are found in dangerous materials, having the spectral fingerprints available in the low-frequency range to expand the reference database can facilitate the detection of nitroguanidine-containing explosives or help identify the presence of gunshot residues at the scene of a crime, or on a suspect, when a firearm was discharged.

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Open Access

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