Scattering of high-velocity He and Ar beams by methane, silane, and germane

Fast He and Ar beams have been scattered by room-temperature CH4, SiH4, and GeH4 to obtain average atom–molecule potentials for He–CH4, He–SiH4, He–GeH4, Ar–CH4, and Ar–GeH4. Somewhat unexpectedly, the potential for He–GeH4 was intermediate between He–CH4 and He–SiH4; this apparent discrepancy, however, correlates with the bond polarities. The potential for Ar–CH4 can be satisfactorily predicted from that for He–CH4 by means of simple potential models and combination rules. The analogous prediction for Ar–GeH4 is unsatisfactory; reasons for the discrepancy are discussed.