Photofragment μ-v-j correlation measured by 1+n′ resonance-enhanced multiphoton ionization: Selective probing of bipolar moments and detection of chiral dynamics

A practical procedure is described to measure photofragment μ-v-j correlations using polarized 1+n′ resonance-enhanced multiphoton ionization with a time-of-flight mass spectrometer detector. Following the theory of Dixon [R. N. Dixon, J. Chem. Phys. 85, 1866 (1986)], the correlations are expressed as the moments of a bipolar harmonic expansion of the correlated angular distribution of photofragment velocity and angular momentum (v and j) about the parent molecule transition dipole, μ. At a fixed detection geometry and on a single rotational transition, polarization control of the dissociating or probing light permits selective determination of targeted moments of the bipolar harmonic expansion. The velocity-dependent spherical tensor moments of the angular momentum distribution depend upon these bipolar moments and are given for a general experimental geometry and for general elliptical polarization of the probing light. Several practical experimental geometries are described that isolate and measure targeted bipolar moments. The bipolar moments that can be measured using elliptical probe polarizations are described. A method for analyzing the symmetries of dissociation dynamics is proposed and used to identify the moments unique to the dynamics of chiral systems.