Vibrational excitation of SF6 scattering from graphite

We have observed vibrationally excited sulfur hexafluoride molecules in direct inelastic scattering from hoc graphite surfaces. The vibrational temperature for the scattered flux has been determined by probing the effect of internal temperature on electron-induced fragmentation observed in mass spectra. The vibrational excitation depends on incident translational energy, E(tr), and a maximum temperature increase of 50 K is reached in direct scattering at E(tr) = 2.5 eV. No effect of surface temperature has been observed at 950-1400 K. Inelastic angular distributions are reproduced by a collision complex model, and the experimental results are related to existing models for vibrational excitation.