Communications: When diffraction rules the stereodynamics of rotationally inelastic collisions.

Following upon our recent work on vector correlations in the Ar–NO collisions [Lemeshko and Friedrich, Phys. Chem. Chem. Phys. 12, 1038 (2010)], we compare model results with close-coupling calculations for a range of channels and collision energies for the He–NO system. The striking agreement between the model and exact polarization moments indicates that the stereodynamics of rotationally inelastic atom-molecule collisions at thermal energies is governed by diffraction of matter waves from a two-dimensional repulsive core of the atom-molecule potential. Furthermore, the model polarization moments characterizing the He–NO, He–O2, He–OH, and He–CaH stereodynamics are found to coalesce into a single, distinctive pattern, which can serve as a “fingerprint” to identify diffraction-driven stereodynamics in future work. [ABSTRACT FROM AUTHOR]