In this paper we present results of coupled channel quantum scattering calculations of the alignment selected thinsp;j=3/2rarr;thinsp;j=1/2 fine structure changing integral cross section for Na(2P)+He. This cross section has in the past been written in terms of a coherent sum of partial wave amplitudes, but we have found that it can be expressed in terms of an incoherent sum of partial cross sections, each labeled by the total angular momentumJand by parity. It is also possible to define an alignment selected wave function for eachJsuch that the azimuthal average of the square of this wave function projected onto each final state is proportional to the magnitude of the partial cross section into that state. ThisJlabeled wave function is thus clearly related to the physical measurables, and we have used it to determine propensities for preservation of asymptotically prepared alignment during collisions. Using a potential surface based on Pascalersquo;sabinitiocalculations, we find that the alignment ratio sgr;perp;/sgr;par;is an increasing function of energy, with a value less than unity at low energy (0.01 eV), but increasing quickly to a value of about 2.0 at 0.04 eV and then more slowly at higher energy, up to a value of 2.7 at 0.2 eV (the highest energy considered). Above 0.02 eV, both the alignment ratio and the alignment selected integral cross sections are in good agreement with values calculated in an accompanying semiclassical study (Kovalenko, Leone, and Delos).An examination of theJlabeled alignment selected scattering wave functions and of the expectation values of lang;OHgr;rang;, lang;Lgr;rang;, and lang;Sgr;rang; indicates that at lowJwhen the initial state is prepared with par; polarization, the dominant state at short range is Sgr; while with perp; polarization the dominant state is Pgr; (i.e., asymptotic alignment is preserved). By way of contrast, this propensity for alignment preservation isnotseen if fluxes or probability densities associated with alignment selected wave functions labeled by the initialorbitalquantum numberl(rather thanJ) are considered. Thisllabeled result is in accord with recent work by Pouilly and Alexander, but the lack of alignment preservation in this case has no relationship with the alignment cross sections, or with the alignment selected plane wave scattering wave function, since thellabeled wave functions must becoherentlycombined to generate this information. The orbital scrambling found for thellabeled solutions thus is not related to measurable properties, and instead the correct picture is provided by theJlabeled solutions, which do show preservation of alignment. We find that even in theJlabeled picture, alignment preservation does not by itself guarantee any specific trend in the alignment ratio for the fine structure transition.
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