Shape resonance determined from angular distribution in D2 (v = 2, j = 2) + He → D2 (v = 2, j = 0) + He cold scattering.

ABSTRACT

We find an l = 2 shape resonance fingerprinted in the angular distribution of the cold (∼1 K) Δj = 2 rotationally inelastic collision of D2 with He in a single supersonic expansion. The Stark-induced adiabatic Raman passage is used to prepare D2 in the (v = 2, j = 2) rovibrational level with control of the spatial distribution of the bond axis of the molecule by magnetic sublevel selection. We show that the rate of Δj = 2 D2-D2 relaxation is nearly two orders of magnitude weaker than that of D2-He. This suggests that the strong D2-He scattering is caused by an orbiting resonance that is highly sensitive to the shape of the long-range potential.