Elastic and rotationally inelastic differential cross sections for He+H2O collisions

Abstract

Elastic and rotationally inelastic cross sections have been measured for He+H2O scattering at two collision energies, 66.3 and 99.0 meV, using the crossed molecular beam technique. The inelastic events are detected by time-of-flight analysis of the scattered He atoms. The data are converted to elastic differential cross sections and inelastic angular-dependent energy loss spectra in the center-of-mass system. They are compared with averaged, full close-coupling calculations of state-to-state cross sections for rotational excitation based on a newly calculated ab initio potential using symmetry-adapted perturbation theory. The agreement with the elastic differential cross sections is excellent. The energy loss spectra are reproduced satisfactorily and among the largest differential cross sections that contributed to the measurements are excitations around all three possible axes for ΔJ=1 but a preference of the excitation around the in-plane C axis for ΔJ=2 transitions.

Communication: Mapping water collisions for interstellar space conditions

“…26,27 In the case of He, very similar DCS results were obtained in Ref. 5, providing an independent check of our method.…”

Glory‐Scattering Measurement of Water–Noble‐Gas Interactions: The Birth of the Hydrogen Bond

“…The lighter systems, particularly that of He, have been the target of numerous theoretical investigations; [5][6][7] the heavier ones (that of Kr and Xe) are practically unknown. Except for He [8] and Ar, [9] accurate experimental characterizations are missing. We show that the systematic investigation of the five water-noble-gas systems, the study of variations of our observables along the series, and comparison with the behavior of analogous systems, prototypical of vdW, provide unique information on the strength and range of intermolecular forces and cast light on the nature and role of interaction components which add to the vdW forces.…”

State-to-state differential and relative integral cross sections for rotationally inelastic scattering of H2O by hydrogen

“…the well--depth and location of zero potential), assuming a Lennard--Jones (12,6) potential. Brudermann et al 3 presented measurements of differential cross sections for H2O+He elastic scattering and reported partially state--resolved inelastic angular dependent energy loss spectra, at two different collision energies. Capelletti et al 12,14 reported determination of the potential parameters for the isotropic component of the D2O--He and D2O-D2 interaction by elastic scattering studies.…”