Instrument Development: A Miniature, High-resolution, Stationary Grating Spatial Heterodyne UV Raman Spectrometer-Towards Miniature UV Raman Sensors and "Raman on a Chip"

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With support from the Chemical Measurement and Imaging program in the Division of Chemistry, Prof. Stanley M. Angel and his students at the University of South Carolina, will develop miniature deep-UV Raman spectrometers of unprecedentedly small size. The miniature Raman spectrometer design is based on a stationary grating, spatial heterodyne spectrometer (SHS) and will have high spectral resolution, a large spectral range and high light throughput. The proposed UV Raman spectrometer is a radically new design that allows mm-size spectrometers with spectral characteristics equal to or better than larger instruments and with higher light throughput than conventional Raman instruments of comparable size, and with high acceptance angle. The proposed work is designed to move towards miniature Raman chemical sensors. The spectrometer will substantially broaden the applicability of Raman for on-line, in-situ, in-vivo, and standoff measurements, in wide-ranging applications. This project will include studies in four major areas: 1) what are the fundamental size limitations of a SHS based Raman spectrometer, 2) how do noise and background sources scale with instrument size, 3) how can an interferometer output be coupled to an external detector, and 4) what new applications are made possible by the availability of a miniature UV Raman spectrometer. The implications of on-line spectroscopic sensors to chemical process monitoring and advanced and additive manufacturing will be explored. Raman spectrometers provide information about the molecular composition of samples by recording small changes in the wavelength (color) of incident light produced by molecular vibrations in the sample. In this project, miniature spectroscopic tools will be developed using cutting-edge technology, opening up whole new areas of analytical measurement possibilities because the small size and UV spectroscopic performance of the miniature SHRS proposed will substantially broaden the range of Raman spectrometer applications. Areas of potential use include chemical process monitoring, on-line chemical kinetics measurements, imaging of biological tissues and cells, standoff forensics analysis, planetary exploration, hand held geological instruments, deep-ocean oceanographic measurements, electronics device characterization, high explosives detection, and many others. This project also provides outstanding opportunities for undergraduates and graduate students to acquire knowledge and skills in spectroscopy, lasers and optics as well as applications of analytical chemistry.