Photodissociation dynamics of OClO at 157 nm

摘要

Photodissociation of OClO at 157.6 nm:excitation has been investigated using the photofragment translational spectroscopic technique; Two distinctive chemical dissociation channels have been observed; one is the binary dissociation process, OClO+hv-->ClO+O; the other one is the,triple dissociation process, OClO+hv-->Cl+O+O. The branching ratio of the binary dissociation channel to the triple dissociation channel is: determined to be 0.59:0.41. Bimodal;vibrational distribution of the ClO product has been observed for the OClO-->ClO(X (II)-I-2)+O(P-3, D-1) channel, implying that two distinctive dissociation routes possibly exist in the binary dissociation process. The bimodal distribution is likely caused by the two dissociation pathways from two excited electronic states:the D((2)A(1)) and E(B-2(1)) states of OClO. These arguments are further supported by the results of the anisotropy parameter measurements or the binary dissociation channels. Experimental; results also show that the OClO+hv-->ClO(X (II)-I-2) + O(S-1) and OClO + hv --> ClO(A (II)-I-2) + O(P-3) channels might also exist in addition to the ClO(X (II)-I-2) + O((3)(P) over bar, D-1) channel. Sn the triple dissociation process, experimental results show that the main product channel is the OClO+hv-->Cl(P-2)+O(D-1)+O(P-3) channel, while the OClO+hv-->Cl(P-2)+O(P-3)S. 0(3P)+0(P-3) channel is the minor one. The; branching-ratio of these two channels is determined to be 0.89:0.11. From the modeling of the time of flight spectra of the O atom product, it is; believed:that the triple dissociation process of OClO is a simultaneous process within the time scale of one rotation period. Two-photon dissociative ionization process OClO+hv-->Cl++O-2+e(-) has also been observed. (C) 1998 American Institute of Physics. [References: 50]