ROTATIONAL-EXCITATION OF HCO PRODUCED BY THE PHOTODISSOCIATION OF ACETALDEHYDE IN A SUPERSONIC JET

The rotational excitation was studied for HCO produced by the photodissociation of acetaldehyde in the excitation wavelength range of 280 approximately 320 nm in a supersonic free jet. The laser-induced fluorescence from the B state of HCO was used to determine the rotational energy in the X(0,0,0) state. The rotational energy partitioned into HCO is estimated to be 6.2 +/- 0.5 kJ mol-1, which is independent of the excitation energy. The result is shown to be accounted for by the rotational excitation due to the torque imparted in the exit channel.