Probing Curve Crossing by Wavelength-Dependent Recoil Anisotropy: The Photodissociation of CF3I at 275−303 nm Studied by Photofragment Translational Spectroscopy

Polarized photofragment translational spectroscopy was used to investigate the photodissociation process CF 3 I → CF 3 + I( 2 P 3/2 ) and CF 3 I → CF 3 + I*( 2 P 1/2 ) in the A absorption band between 275 and 303 nm. We determined the fragment recoil anisotropies β(I) and β(I*) and the branching ratio of the products I and I* as a function of the excitation wavelength λ exc which covers most of the overlapping transitions 3 Q 1 ← X and 3 Q 0 ← X. The results are interpreted within the mechanistic scheme that involves three potential energy surfaces 3 Q 1, 3 Q 0, and 1 Q 1 . The variation in the anisotropy β(I*) and the product-yield ratio I/I* with λ exc is shown to reflect the variation of mixed 3 Q 0 and 1 Q 1 character of the adiabatic states when excited near the avoided curve crossing.