Steric asymmetry in state-resolved NO-Ar collisions

New experimental results are reported on state-dependent steric effects in NO-Ar inelastic scattering. The NO molecules are selected in the J = 1/2(-) h-doublet state of the electronic ground state and oriented relative to th e incident Ar atoms. The steric asymmetry, S = (sigma(NO) - sigma(ON))/(sig ma(NO) + sigma(ON)), has been measured as a function of the final rotationa l state J'. Ln a previous study, quantum-mechanical scattering calculations were found to predict strong oscillations in S, but experimental evidence for this behaviour was not conclusive. The results of experiments presented here provide clear evidence of the qualitative correctness of the theoreti cal calculations. (C) 1999 Elsevier Science B.V. All rights reserved.