Polarization of atomic photofragment fluorescence for excitation along a Fano profile: A quantum-mechanical study

Abstract

A quantum-mechanical description of the polarization of the fluorescence from photofragments, obtained by excitation along a Fano profile, is presented. For excitation on a Fano profile, dissociation can occur via two indistinguishable pathways, i.e., dissociation via the resonance and via direct excitation to the continuum. This gives rise to quantum interference effects, which result in an asymmetric profile in the photon absorption spectrum. The effect of the interference on the polarization of the photofragments fluorescence is investigated. The polarization as a function of the excitation energy varies asymmetrically around the resonant excitation energy. However, in contrast to intuition, the polarization changes in a symmetric way around an energy which is shifted from the resonant excitation energy. Simple formulas to calculate the polarization for different rotational and electronic transitions are provided.