HD is supersonically coexpanded with its collision partner, H2 or D2, into a vacuum chamber so that the collision temperature is reduced to 1-2 K, which restricts the incoming partial waves to s and p in the scattering process. Using Stark-induced adiabatic Raman passage (SARP), nearly 100% of the HD molecules is prepared in the vibrational-rotational magnetic substate |v=1, j=2, m=0&gt; where the polarization of the pump and Stokes lasers in the SARP process selects the HD bond axis to point preferentially either parallel or perpendicular to the beam direction. Collisionall relaxed HD (v=1, j=0) is detected with a time-of-flight mass spectrometer using 2+1 resonance enhanced multiphoton ionization (REMPI). The cross section is found to depend strongly on the alignment of the HD bond axis. Partial wave analysis of our data shows that rotational relaxation involves exchange of rotational angular momentum between the colliding partners.

Rotationally inelastic scattering of HD (v=1, j=2) with H2 or D2 near 1 Kelvin

255th National Meeting (2018)

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