A pulsed laser investigation is performed to study the detailed effects of electronic angular-momentum alignment on the cross section for the energy-transfer process Ca ( 4 s 4 p 3 P 1 ) + Ca ( 4 s 4 p 3 P 1 ) → Ca ( 4 s 4 p 1 P 1 ) + Ca ( 4 s 2 ) . A uniform magnetic field imposed by a set of Helmholtz coils is used to systematically precess the initial state orbitals with a well-defined period, allowing different alignments to be sampled at different time delays after the pulsed laser excites and aligns the Ca ( 4 s 4 p 3 P 1 ) states. The polarization effects in this collision process are striking. For example, the cross section for two atoms both in the m j = 0 magnetic substrate is 13 times larger than the cross section for two atoms that are both in the m j = 1 (or -1) substrate, where the quantization axis is taken to be along the relative velocity vector of the collision. The initial m -sublevel dependence of this three-vector correlation process can be completely described with eight fundamental parameters, five of which are accurately obtained. In addition, the coarse energy dependence of these parameters is deduced.
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