Uv Raman Microscopy: Spectral and Spatial Selectivity and Even High Sensitivity

Abstract

We have constructed a new UV Raman microspectrometer designed around an Olympus microscope, a single spectrograph and an intensified CCD detector (Fig. 1). We utilize CW excitation from either an intracavity frequency doubled Ar+ laser (257, 244, 229 nm) or a Kr+ laser (206 nm). We optimized the throughput by utilizing specially prepared dielectric coated Rayleigh rejection filters.In one application we used this instrument to speciate and determine the spatial distribution of non diamond carbon species in CVD diamond samples (Fig. 2). We find that these non diamond carbon species are localized in the interstitial areas between diamond crystals.In another application we demonstrated the utility of UV Raman microspectroscopy for the rapid, incisive and non-destructive characterization of meteorites and interplanetary dust particles (IDP). In addition to probing the structure and distribution of predominant mineral matrices of these materials, UV excitation enables us to the characterize the small but significant carbonaceous components included within these samples.