15min:

B. J. MCCALL, A. J. HUNEYCUTT, R. CASAES, R. J. SAYKALLY, Department of Chemistry, University of California at Berkeley, Berkeley, CA 94720; C. M. LINDSAY, T. OKA, Department of Chemistry, University of Chicago, Chicago, IL 60637; M. FUSHITANI, Y. MIYAMOTO AND T. MOMOSE, Division of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.

We report the results of our preliminary investigations into the suitability of condensed phase parahydrogen as a Raman-shifting medium for the generation of tunable infrared radiation for cavity ringdown laser absorption spectroscopy (CRLAS). We have observed the conversion of 10 ns pulses of 532 nm radiation into first-, second-, and third-order vibrational Stokes radiation in bulk liquid and solid parahydrogen after a single 11-cm pass. Surprisingly, we find that liquid-H₂ yields more efficient conversion than solid-H₂ with certain focal geometries, and that in the case of the solid, a collimated or loosely focused pump geometry is more efficient than a tight focus. We also will discuss our more recent studies of Raman shifting using the longer ( 100 ns) pulses of an alexandrite laser.