A Velocity Map Ion-imaging Study on Ketene Photodissociation at 218 nm

Abstract

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 (υ =0 and υ =1) exhibit significant rotational excitation. Furthermore the rotational excitation of CO at the υ =0 level is noticeably higher than that at the υ =1 level. (ii) It was found that the major photodissociation pathway of ketene at 218 nm is the CH 2 (ã 1 A 1)+CO(X 1 Σ +) channel, while the CH 2 (b 1 B 1)+CO(X 1 Σ +) channel and the CH 2 (X 3 B 1)+CO(X 1 Σ +) channel are also likely present. (iii) The anisotropy parameters β of CO different rovibronic states all appear to be larger than zero. No significant difference is observed at the two vibrational states.