Polarization studies as a probe of photodissociation dynamics

Abstract

A linearly polarized tunable CW dye laser was used to photodissociate K2 from the ground X1Σ+g state through the continuum of the B1Πu state. By monitoring the resultant atomic D2 fluorescence, we were able to measure the pure bound‐free absorption profile. At the same time, the polarization of the atomic fluorescence was measured as a function of laser excitation frequency. We believe this to be the first observation of a large variation in the polarization, ranging from plus 15±2% to minus 6.3±0.4% as a function of laser wavelength. The results can be explained in terms of molecular rotation during dissociation. These results are consistent with a completely adiabatic model for the dissociation. However, there are significant discrepancies between these model results and the experimental observations when hyperfine depolarization effects are included in the calculation. The origin of these discrepancies is not understood.