Ion imaging studies of product rotational alignment in collisions of NO with Ar

Abstract

Abstract The collision-induced rotational alignment of NO ( X 2 Π 1/2 , v=0, j=4.5 , 8.5, 11.5, 12.5, and 15.5) is measured for rotationally inelastic scattering of NO ( X 2 Π 1/2 , v=0, j=0.5) with Ar at 520 ± 70 cm−1 of center-of-mass collision energy. The experiments are performed by velocity-mapped ion imaging with polarized 1+1′ REMPI of the scattered NO product. Differential cross-sections (DCSs), corrected for alignment effects, are also reported. While the alignment correction is important, it does not change the positions of the observed rotational rainbows. The alignment moments and DCSs are compared with calculations using Alexander's CCSD(T) PESs. The theoretical and experimental DCSs show excellent agreement, as do the theoretical and experimental alignment moments for low Δj. For high Δj collisions and back-scattered trajectories, which sample the hard wall of the PES, the theoretical and experimental alignment moments show less agreement.