Wavelength Dependence on the Forensic Analysis of Glass by Laser Induced Breakdown Spectroscopy

Abstract

The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Laser Induced Breakdown Spectroscopy (LIBS) can be used for the chemical characterization of glass to provide evidence of an association between a fragment found at a crime scene to a source of glass of known origin. Two different laser irradiances, 266 nm and 1064 nm, were used to conduct qualitative and quantitative analysis of glass standards. Single-pulse and double-pulse configurations and lens-to-sample-distance (LTSD) settings were optimized to yield the best laser-glass coupling. Laser energy and acquisition timing delays were also optimized to ABSTRACTLaser Induced Breakdown Spectroscopy (LIBS) can be used for the chemical characterization of glass to provide evidence of an association between a fragment found at a crime scene to a source of glass of known origin. Two different laser irradiances, 266 nm and 1064 nm, were used to conduct qualitative and quantitative analysis of glass standards. Single-pulse and double-pulse configurations and lens-to-sample-distance (LTSD) settings were optimized to yield the best laser-glass coupling. Laser energy and acquisition timing delays were also optimized to result in the highest signal to noise ratio. The crater morphology was examined and the mass removed was calculated for both the 266 nm and 1064nm irradiations. The analytical figures of merit suggest that the 266 nm and 1064 nm wavelengths are capable of good performance for the forensic chemical characterization of glass. The results presented here suggest that the 266 nm laser produces a better laser-glass matrix coupling resulting in a better stoichiometric representation of the glass sample. The 266 nm irradiance is therefore recommended for the forensic analysis and comparison of glass samples.

Short Communication on “Direct compositional quantification of (U-Th)O2 - MOX nuclear fuel using ns-UV-LIBS and chemometric regression models”

“…With the reduction of laser wavelength, the mass removal increase, whichis due to the better energy coupling provided, combined with reduced plasma shielding. Due to higher mass removal at 266 nm than 532 nm and 1064 nm, the crater effect occurs with fewer number of laser pulses[5,17,18] .…”