Determination of μ-v-j vector correlations in photodissociation experiments using 2+n resonance-enhanced multiphoton ionization with time-of-flight mass spectrometer detection

A practical method is described for 2+n resonance-enhanced multiphoton-ionization probing of photofragment mu-v-j correlations arising in molecular photodissociation on a linearly polarized single-photon electric-dipole transition. The scheme uses polarized spectroscopy on the two-photon resonant transition with velocity detection by time-of-flight mass spectrometry. The technique is based on the theory of Kummel, Sitz, and Zare for polarized two-photon detection of angular momentum alignment and orientation and Dixon's bipolar moment description of vector correlations. Optimal experimental and polarization geometries are described for selective measurement of targeted bipolar moments. The utility of the technique is demonstrated in experiments using 2+1 REMPI to probe methyl radical vector correlations in the 266 nm photodissociation of methyl iodide. (C) 2000 American Institute of Physics. [S0021-9606(00)00414-1].