Photodissociation of the linear Ar-I_2van der Waals complex: Velocity-map imaging of the 1_2fragment

摘要

Photodissociation of the Ar-I_21:1 linear van der Waals complex is studied over the 490-520 nmregion using the velocity-map imaging technique. Molecular iodine, and both the T-shaped andlinear Ar-I_2(X, υ"=0) ground-state complexes absorb strongly in this range, and these transitionsaccess both the bound and dissociative regions of the I_2(B) state. We measure the angle-speeddistribution of vibrationally excited I_2(B,υ')state products by resonant 1+1 ionization via theEandf ion-pair states, forming 1_2+,which is imaged under velocity-mapping conditions. The images showa strong angular anisotropy, which is the same for all excitation energies, spanning from the boundregion to above the molecular dissociation limit. The observed angular anisotropy of the I_2fragments is consistent with a direct dissociation of linear Ar-I_2complexes promoted to the innerrepulsive potential wall of the Ar+I_2(B,υ')potential energy surface.