UV Raman Microspectroscopy: Spectral and Spatial Selectivity with Sensitivity and Simplicity

Abstract

The high sensitivity, selectivity, spatial resolution, and ease of operation of UV Raman microspectr oscopy is demonstrated with the use of a new highly efficient UV Raman microspectrometer with excitation at 244 nm. Single spectrograph dispersion combined with special new filters for the rejection of Rayleigh scattering improves the throughput efficiency by a factor of approximately 4 in comparison to a triple-stage spectrograph. The instrument has a spatial resolution of approximately 3 μm × 9 μm in the lateral (X–Y) plane, and 10 μm or less in the axial (Z) plane. UV resonance Raman spectra of nucleic acids are selectively excited from spatially resolved areas of a single paramecium by using low continuous-wave (cw) excitation powers and short accumulation times to minimize sample damage. High signal-to-noise Raman spectra are excited from spatially resolved areas of chemical-vapor-deposited (CVD) diamond films. We demonstrate, for the first time, the ability to probe the spatial distribution of the nondiamond carbon impurities in CVD diamond films. The amorphous carbon band at ∼ 1553 cm −1 is resolved from the normally broad ∼ 1600-cm −1 nondiamond carbon band.