CROSSED-BEAM ROVIBRATIONAL ENERGY-TRANSFER FROM S-1 GLYOXAL .2. UNIFORM SCATTERING CHARACTERISTICS FROM THE INITIAL LEVEL-0(0), LEVEL-5(1),AND LEVEL-8(1)

Results are reported for an extension to higher initial states of cros sed molecular beam inelastic scattering from (1)A(u) trans-glyoxal (CH OCHO) by He collisions with 95-meV (770-cm(-1)) center-of-mass collisi on energy. A laser pump prepares glyoxal in the initial level nu(5)' = 509 cm(-1) or nu(8)' = 735 cm(-1) with high rotational selectivity ab out the top axis; K' = 0 for nu(5)' and K' = 0-3 for vs'. A dispersed fluorescence probe detects the final states of rotationally and of rov ibrationally inelastic scattering with resolution of Delta K transitio ns. Semiquantitative relative cross sections are obtained for the stat e-to-state scattering. The rovibrational channels show the same extrem e selectivity that is observed for scattering from lower levels. Only a single quantum change in the lowest frequency mode, the CHO-CHO tors ion nu(7)' = 233 cm(-1), may be securely assigned. Scattering to much closer vibrational levels is not competitive. The state-resolved inela stic scattering characteristics of the three levels 0(0), 5(1), and 8( 1) are now seen to be identical to within experimental uncertainty. Th e similarity involves both the competition between the rotational and rovibrational scattering channels as seen in the relative cross sectio ns and the distribution of cross sections for the various Delta K proc esses within these channels. The experimental results are in agreement with the three-dimensional quantal scattering predictions of Kroes, R ettschnick, and Clary.