Quantum interference in collision-induced energy transfer for CO (A1Π, v=0/e3Σ−, v=1)–HCl (X1Σ) system studied by OODR-MPI spectroscopy

Quantum interference effect (QIE) in rotational energy transfer within CO (A1Π, v=0/e3Σ−, v=1) mixed states in collision with HCl are observed with the interference phase angle θST of 101 and 110° for ΔJ=±1 transition, respectively, from the initial J=12 and 13 states. In comparison with the previous similar experiments with He et al. as collision partner, which all give a θST<90°, the interference for a same CO transition in collision with HCl changes from constructive to destructive or the reverse since cos θST becomes negative. The bigger θST may be explained by the long-range dipole–dipole interaction of proportional to R−3. The physical significance of θST is discussed in some details.