Photodissociation dynamics of triatomic molecules

Abstract

Calculations are presented for the polarization anisotropy, R = (I ‖ - I ⊥)/(I ‖ + 2I ⊥), of the fragment fluoresence (AB* →AB + hv) when a triatomic molecule (ABC) is photodissociated by a beam of linearly polarized radiation. Expressions are developed relating the polarization anisotropy to the predissociation lifetime τ of the [ABC*] complex under the assumptions that (1) the motion of the [ABC*] complex can be described by the classical motion of the prolate symmetric top, (2) the AB* excited fragment rotates in the plane of the [ABC*] complex at the time of dissociation and (3) the absorption and emission processes can be described by classical hertzian dipole oscillators. The time averaged autocorrelation function of a free symmetric top, <Dmm′ (2)(δΩ(t))>, is used to find R(τ) for the dissociation of an [ABC*] complex in a single J, K level and for this quantity averaged over a Boltzmann distribution of J, K levels.