Knowledge Bank

State-to-state energy transfer from selected rovibronic levels in $S1$ $D2CO$ has been studied with crossed molecular beams. A UV laser is used to prepare an initial $S1$ state in $D2$ CO. After inelastic scattering from He, Ar or $H2$ in the secondary beam, the newly populated $S1$ states are monitored with dispersed $S1\to S0$ fluorescence. The detection of new states produced by the inelastic scattering is limited only by the fluorescence resolution and sensitivity. In the case of $D2CO$, we have been able to obtain relative inelastic cross sections for both rotationally and rovibrationally inelastic scattering. These data reveal distinctive propensity rules. They also provide instructive comparisons with analogous inelastic scattering from the 12-atom molecule glyoxal. Perhaps most importantly, they establish benchmarks for 3- dimensional quantal scattering calculations recently provided by Kroes, Echave and Clary.