			15min:

THE C-H STRETCH SPECTRUM OF ETHYLENE IN LIQUID HELIUM DROPLETS.

C. MICHAEL LINDSAY, WILLIAM K. LEWIS AND ROGER E. MILLER, Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599.

In this talk we report our study of ¹²C₂H₄ monomer and its clusters in ⁴He with the new, ``second generation" helium droplet/infrared spectroscopy apparatus at UNC. The region containing the ₁₁ and ₉ asymmetric C-H stretches of the monomer was scanned using a tunable, cw OPO aligned collinearly with the droplet beam and detected with a quadrupole mass spectrometer. Rotationally resolved spectra were observed with line widths as narrow as 0.08 cm^-1, FWHM. Details of the new instrument and the analysis of the spectra will be presented.