Dynamics of gas-surface interactions. Temperature dependence of the translational relaxation of polyatomic gases on silica and platinum

Single-collision translational energy excitation of n-butane, 1 -chlorobutane, and n-octane on hot silica and platinum surfaces at T_s has been studied by modulated beam mass spectrometry in the range T_s = 350-750 K. The linear decline of the derived translational accommodation coefficient with T_s contrasts with previous results on vibrational relaxation for the same systems and is taken as evidence of (1) the inverse dependence of nonactivated sticking on incident kinetic energy via detailed balance and (2) the weak coupling of translational and vibrational modes in gas-surface collisions