Determination of velocity distribution, angular distribution, and vector correlation of photofragments using sub-Doppler fluorescence-imaging method

摘要

With sub-Doppler resolution, the fluorescence-imaging techniques can be modified to determine velocity distribution, angular distribution, and vector correlation of state-selected photofragments, even in an uncollimated molecular beam. This new method is proposed as "sub-Doppler fluorescence-imaging" in which two experimental schemes are developed. The dependence of fluorescence intensities, at any selected velocity and recoil angle in the scattering plane, with respect to the variation of polarization vectors of the probe laser and emitted fluorescence is derived using density matrix formalism. The intensity patterns of photofragments with v-J and mu-v-J correlations are simulated. The laser ablation of B atoms at 248 nm demonstrates the feasibility of this method. Two-dimensional velocity distribution of the laser-ablated B(P-2(1/2,3/2)0) atoms is measured and the ablation mechanism is discussed. (C) 2000 American Institute of Physics. [S0021-9606(00)00938-7]. [References: 30]