Polarized Fluorescence of Fragments in a Gas Phase and the Mechanism of Photodecay: I. Stationary Anisotropy

摘要

The polarization response of an ensemble of photofragments is studied in the A + hV_(abs) -> B~* + products, B~* -> B + hV_(em) reaction under collisionless conditions. Within the framework of formalism of conditional probability functions, the explicit expression is obtained for anisotropy of polarized fluorescence of the fragments. This approach makes it possible to take into account the contribution to the rotational excitation of fragments from rotation of the initial molecule and from the thrust caused by the disruption of chemical bonds. It is shown that the stationary anisotropy of fluorescence is quite sensitive to the specific features of the photofragmentation process and substantially depends on the relation between the rotational predissociation time, the lifetime of the fragment in the excited electronic state, and the average period of free rotation of initial molecules and fragments, which allows one to obtain information on the photodecay dynamics from polarization data.