Measurement of product rotational alignment in associative-ionization collisions between polarized Na(3p) atoms

We have studied the effect of reactant Na(3p) polarization on the rotational angular momentum alignment of product ${\mathrm{Na}}_2$ ${\mathrm{}}^{+}$ ions arising from associative-ionization (AI) collisions. Our results show that sensitivity of the AI rate constant to initial atomic polarization persists even when all hyperfine states are populated with broadband (3 ${\mathrm{cm}}^{\mathrm{-}1}$) pulsed laser excitation of Na${(\mathrm{}}^2$ $P_{3/2}$) and that the spatial distribution of product rotational angular momentum vectors is anisotropic. We discuss a qualitative description of the collision process consistent with our measurements which indicates that σ-orbital symmetry is preferred to π-orbital symmetry as the colliding partners approach.