Long-Wave, Infrared Laser-Induced Breakdown (LIBS) Spectroscopy Emissions from Energetic Materials

Abstract

Laser-induced breakdown spectroscopy (LIBS) has shown great promise for applications in chemical, biological, and explosives sensing and has significant potential for real-time standoff detection and analysis. In this study, LIBS emissions were obtained in the mid-infrared (MIR) and long-wave infrared (LWIR) spectral regions for potential applications in explosive material sensing. The IR spectroscopy region revealed vibrational and rotational signatures of functional groups in molecules and fragments thereof. The silicon-based detector for conventional ultraviolet–visible LIBS operations was replaced with a mercury–cadmium–telluride detector for MIR–LWIR spectral detection. The IR spectral signature region between 4 and 12 μm was mined for the appearance of MIR and LWIR–LIBS emissions directly indicative of oxygenated breakdown products as well as dissociated, and/or recombined sample molecular fragments. Distinct LWIR–LIBS emission signatures from dissociated-recombination sample molecular fragments between 4 and 12 μm are observed for the first time.