Deep-ultraviolet resonance Raman spectroscopy (DUVRRS) is a promising approach to stand-off detection of explosive
traces due to large Raman cross-section and background free signatures. In order to design an effective sensor, one must
be able to estimate the signal level of the DUVRRS signature for solid-phase explosive residues. The conventional
approach to signal estimation uses scattering cross-sections and molar absorptivity, measured on solutions of explosives
dissolved in an optically-transparent solvent. Only recently have researchers started to measure solid-state cross-sections.
For most solid-phase explosives and explosive mixtures, neither the DUV Raman scattering cross sections nor the
optical absorption coefficient are known, and they are very difficult to separately measure. Therefore, for a typical solid
explosive mixture, it is difficult to accurately estimate Raman signal strength using conventional approaches. To address
this issue, we have developed a technique to measure the Raman scattering strength of optically-thick (opaque)
materials, or “Raman Albedo”, defined as the total power of Raman-scattered light per unit frequency per unit solid
angle divided by the incident power of the excitation source. We have measured Raman Albedo signatures for a wide
range of solid explosives at four different DUV excitation wavelengths. These results will be presented, and we will
describe the use of Raman Albedo measurements in the design and current construction of a novel stand-off explosive
sensor, based on dual-excitation-wavelength DUVRRS.