Scattering of thermal He beams by crossed atomic and molecular beams. IV. Spherically symmetric intermolecular potentials for He+CH4, NH 3, H2O, SF6

John T. Slankas, Mark Keil, Aron Kuppermann

Research output: Contribution to journalArticlepeer-review

55 Scopus citations

Abstract

Differential scattering cross sections are measured for He+CH4, NH3, H2O, and SF6, using the crossed molecular beams technique. These data, which are sensitive to the van der Waals attractive minima and adjacent regions of the intermolecular potential, are interpreted in terms of central-field models. No evidence is found for quenching of the observed diffraction oscillations. The interactions of the isoelectronic hydrides CH4, NH3, H2O with He are found to have decreasing van der Waals radii in this sequence, and their attractive wells all have similar depths. However, the He+SF6 attractive well is found to be anomalously deep, and provides a counter example to the supposition that only the polarizability of the least polarizable of the interacting partners (atoms or molecules) correlates with the van der Waals well depth. Simple combination rules for predicting unlike-pair potential parameters from the corresponding like-pair ones are tested and found inadequate.

Original languageEnglish
Pages (from-to)1482-1491
Number of pages10
JournalJournal of Chemical Physics
Volume70
Issue number3
DOIs
StatePublished - 1 Jan 1979
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy (all)
  • Physical and Theoretical Chemistry

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