Knowledge Bank

The 454.5 nm line of an $Ar+$ laser has been used to populate the lowest vibrational level of the $S1(1Au)$ electronic state of glyoxal. At sample pressures of two mtorr the average excited state molecule undergoes no collisions before relaxing to the ground state. One of the collision free relaxation processes has recently been found to be dissociation. The rate of dissociation has been studied at various pressures and laser intensities. The dissociation has been found to be a unimolecular decay channel of the $S1$ state. The quantum yield of the dissociation process under collision free conditions is about 0.63. The laser line pumps preferentially eight rotational levels. The dissociation rate from several of these explicit levels has been measured. The quantum yield of dissociation appears not to have any strong dependence on the $S1$ rotational level excited.