INELASTIC-SCATTERING OF ROTATIONALLY EXCITED GLYOXAL BY H-2 AT E = 80 MEV

Results of quantum calculations on rotationally and vibrationally inelastic scattering of rotationally excited 1A(u)(S1) trans-glyoxal (in collisions with H2, at a collision energy of 80 meV) are reported. These results are used to assess the influence of sequential collisions on a recent experiment on glyoxal + H2. For \DELTA-K\ > 3, the cross sections for rotationally inelastic scattering sigma(0(0),K = k --> 0(0),K' + DELTA-K) depend exponentially on (DELTA-K)2 (and not on the energy difference between the initial and final states), which shows that the rotationally inelastic scattering is dominated by angular momentum transfer rather than by energy transfer. Taking into account sequential collisions leads to a substantial improvement in the agreement between the calculated and experimental values of the rotationally resolved cross sections for excitation of the lowest frequency nu-7 torsional mode.