A velocity map ion-imagring study on ketene photodissociation at 218 nm

Photodissociation dynamics of ketene at 218 nm has been investigated using the velocity map ion-imaging method. Both angular and translational energy distributions for the CO products at different rotational and vibrational states have been obtained. The 2+1 REMPI spectrum of CO products is also obtained. The results are as bellow: (i) CO products in the first two vibrational states (v ''=0 and v ''=1) exhibit significant rotational excitation. Furthermore the rotational excitation of CO at the v ''=0 level is noticeably higher than that at the v ''=1 level. (ii) It was found that the major photodissociation pathway of ketene at 218 mn is the CH2((a) over tilde (1)A(1))+CO(X(1)Sigma(+)) channel, while the CH2((b) over tilde B-1(1))+CO(X(1)Sigma(+)) channel and the CH2((X) over tilde B-3(1))+CO(X(1)Sigma(+)) channel are also likely present. (iii) The anisotropy parameters beta of CO different rovibronic states all appear to be larger than zero. No significant difference is observed at the two vibrational states.