HIGH-RESOLUTION STUDIES OF OH/D(A, v=1)-Ar VIBRATIONAL PREDISSOCIATION

1. M.T. Berry, M.R. Brustein, and M.I. Lester, J. Chem. Phys. 92, 6469 (1990) 2. Y. Lin, Ph.D. Thesis, Emory University (1991). 3. G.W. Ewing, J. Chem. Phys, 72, 2096 (1980).Author Institution: Department of Chemistry, Emory UniversityRapid vibrational predissociation of OH(A, v=1)-Ar is evident in the A-X excitation and resolved fluorescence $spectra^{1,2}$. In excitation, predissociation causes homogeneous broadening of the rotational lines. Berry $et. al.^{1}$ reported linewidths ranging from $<$0.05 to $0.26 cm^{-1}$, which were determined from spectra taken at a resolution of $0.1 cm^{-1}$. They noted that they predissociation rate decreased with increasing excitation of the van der Waals stretch, but in a manner that was not consistent with simple energy or momentum gap $laws^{3}$. Departures from these models were also indicated by the spectra for $OD(A, v=1)-Ar^{2}$. Based on the smaller vibrational interval for OD(A), a V-T energy gap model predicts that OD-Ar will predissociate much more rapidly that OH-Ar. However, homogeneous line broadening could not be detected in OD(A, v=1)-Ar spectra recorded at $0.08 cm^{-1}$ $resolution^{2}$. In order to examine the predissociation dynamics in more detail, we are using a pulse amplified ring dye laser system to record OH/D (A, v=1)-Ar bands at $0.01 cm^{-1}$ resolution. Results from these measurements, and their dynamical implications, will be discussed