Scattering of N-2 Molecules from Silica Surfaces: Effect of Polymorph and Surface Temperature

The inelastic scattering of N-2 molecules from silica surfaces, taken at 100 K, has been investigated by adopting a semiclassical collision model in conjunction with the appropriate treatment of the long-range interaction forces. Such forces promote the formation of the precursor state that controls all basic elementary processes occurring at the gas-surface interphase. The probabilities for the different elementary surface processes triggered by quartz are determined and compared with those recently obtained for another silica polymorph (cristobalite). In addition, the final roto-vibrational distributions of N-2 molecules undergoing inelastic scattering have been characterized. N-2 molecules, impinging on both considered surfaces in low-medium vibrational states, preserve the initial vibrational state, while those inelastically scattered are rotationally excited and translationally colder. The surface temperature effect, investigated by raising the temperature itself from 100 K up to 1000 K, emerges more sharply for the cristobalite polymorph, mainly for the molecules impinging in the ground roto-vibrational state and with low collision energies.

Automated summary

The inelastic scattering of N-2 molecules from silica surfaces at 100 K was investigated using a semiclassical collision model with appropriate treatment of long-range interaction forces. The study determined the probabilities for different elementary surface processes triggered by quartz and compared them with those for cristobalite. In addition, the final roto-vibrational distributions of N-2 molecules undergoing inelastic scattering were characterized, showing different effects for the two silica polymorphs.