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Inverse analysis of diffuse-reflectance spectra for surface-distributed PETN particles

Threat chemicals such as explosives may persist on surfaces, enabling them to be detected by non-contact or standoff optical methods such as diffuse IR reflectance. However, due to particle size effects and optical coupling to the substrate, their IR spectral signatures will differ from laboratory reference measurements of bulk materials. This study presents an inverse analysis of diffuse IR reflectance from sparsely surface-distributed particles of the explosive PETN. A methodology using spectrum templets is applied for inverse analysis of measured spectra. The methodology is based on a generalization of extended multiplicative signal correction (EMSC). The results of this study demonstrate application of the inverse analysis methodology for extraction of spectral features for surface-distributed particles of specified dielectric response.