APPLICATIONS OF A NEW 206.5-NM CONTINUOUS-WAVE LASER SOURCE - UV RAMAN DETERMINATION OF PROTEIN SECONDARY STRUCTURE AND CVD DIAMOND MATERIAL PROPERTIES

We demonstrate the utility of a new 206.5-nm continuous-wave UV laser excitation source for spectroscopic studies of proteins and CVD diamon d, Excitation at 206.5 nm is obtained by intracavity frequency doublin g the 413-nm line of a krypton-ion laser, We use this excitation to ex cite resonance Raman spectra within the pi-pi amide transition of the protein peptide backbone. The 206.5-nm excitation resonance enhances the protein amide vibrational modes. We use these high signal-to-noise spectral data to determine protein secondary structure, We also demon strate the utility of this source to excite CVD and gem-quality diamon d within its electronic band-gap. The diamond Raman spectra have very high signal-to-noise ratios and show no interfering broad-band lumines cence. Excitation within the diamond bandgap also gives rise to narrow photoluminescence peaks from diamond defects. These features have pre viously been observed only by cathodoluminescence measurements, This n ew continuous-wave UV source is superior to the previous pulsed source s, because it avoids nonlinear optical phenomena and thermal sample da mage; Photoluminescence.