Deep UV Raman/Fluorescence (DUV-RF) Stand-Off Sensor for Lunar Science

This proposal enables development a miniature, low power consumption, fused deep UV Raman and native fluorescence (DUV-RF) stand-off sensor. The proposed fused instrument has the ability to measure the spatial distribution of chemical species containing C, N, H, O, S, Cl, and/or water, ice, and hydrated minerals on a 1-5 mm spatial scale enabled by a novel set of wide aperture, high sensitivity ultraminiature deep UV Raman spectrometers. Raman spectroscopy is a non-contact, non-destructive, method of identifying unknown materials without the need for sample acquisition and processing. This technique is ideal for in situ exploration from extraterrestrial Rovers or landers. There are three main advantages of deep UV Raman methods over near-UV, visible or near-IR counterparts. 1) Rayleigh-law: signal enhancement of 20x at 248nm compared to excitation at 532nm. 2) Resonance: much higher signal enhancements; for water 5 times greater than Rayleigh-law enhancement alone, for a combined effect over 120x between 248 nm and 532 nm. 3) With excitation below 250nm, Raman scattering bands occur in a fluorescence-free region of the spectrum. At longer excitation wavelengths fluorescence from target or surrounding materials overwhelm Raman emissions and require gating with high power lasers with narrow pulse widths leading to sample alteration/damage. When deep UV Raman is combined with native fluorescence, it becomes possible to characterize mineral alterations and detect trapped chemicals with exquisite sensitivity and differentiability. The New Frontiers has placed a South pole-Aitken Basin sample return as a future mission scenario. Using the enhanced detection capabilities of DUV-RF, water, ice and chemical species can be detected and mapped to provide an understanding of their distribution in the lunar regolith.