Damping of total differential cross sections: Observations and empirical anisotropic potentials for HeC2H2 and HeOCS

Laurie J. Danielson; Karen M. McLeod; Mark Keil

doi:10.1063/1.453740

Damping of total differential cross sections: Observations and empirical anisotropic potentials for HeC₂H₂ and HeOCS

Laurie J. Danielson, Karen M. McLeod, Mark Keil

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Abstract

Differential cross section (DCS) measurements are reported for scattering of a He atomic beam by crossed beams of Ar, C₂H₂, CO ₂, and OCS. Relative to the HeAr diffractive structure, the HeC ₂H₂ DCS is moderately damped at small scattering angles and severely damped at large scattering angles; the HeCO₂ and HeOCS DCS's are severely damped for all scattering angles. This damping directly reflects increasing anisotropy of the scattering partner from Ar (none) to C₂H₂ (moderate) to CO₂ and OCS (strong). Even though the present data do not resolve elastic from inelastic contributions, the HeCO₂ results are consistent with partially resolved inelastic DCS measurements [U. Buck, H. Meyer, M. Tolle, and R. Schinke, Chem. Phys. 104, 345 ( 1986) ] and therefore complement them. Consequently the data are used to obtain empirical anisotropic intermolecular potentials for HeC₂H ₂ and HeOCS within the infinite-order-sudden approximation. These reproduce the total (unresolved elastic + inelastic) DCS measurements very well, even though the angular asymmetry of OCS is ignored in the analysis.

Original language	English
Pages (from-to)	239-248
Number of pages	10
Journal	Journal of Chemical Physics
Volume	87
Issue number	1
DOIs	https://doi.org/10.1063/1.453740
State	Published - 1 Jan 1987
Externally published	Yes

ASJC Scopus subject areas

General Physics and Astronomy
Physical and Theoretical Chemistry

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title = "Damping of total differential cross sections: Observations and empirical anisotropic potentials for HeC2H2 and HeOCS",

abstract = "Differential cross section (DCS) measurements are reported for scattering of a He atomic beam by crossed beams of Ar, C2H2, CO 2, and OCS. Relative to the HeAr diffractive structure, the HeC 2H2 DCS is moderately damped at small scattering angles and severely damped at large scattering angles; the HeCO2 and HeOCS DCS's are severely damped for all scattering angles. This damping directly reflects increasing anisotropy of the scattering partner from Ar (none) to C2H2 (moderate) to CO2 and OCS (strong). Even though the present data do not resolve elastic from inelastic contributions, the HeCO2 results are consistent with partially resolved inelastic DCS measurements [U. Buck, H. Meyer, M. Tolle, and R. Schinke, Chem. Phys. 104, 345 ( 1986) ] and therefore complement them. Consequently the data are used to obtain empirical anisotropic intermolecular potentials for HeC2H 2 and HeOCS within the infinite-order-sudden approximation. These reproduce the total (unresolved elastic + inelastic) DCS measurements very well, even though the angular asymmetry of OCS is ignored in the analysis.",

author = "Danielson, {Laurie J.} and McLeod, {Karen M.} and Mark Keil",

year = "1987",

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doi = "10.1063/1.453740",

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T2 - Observations and empirical anisotropic potentials for HeC2H2 and HeOCS

AU - Danielson, Laurie J.

AU - McLeod, Karen M.

AU - Keil, Mark

PY - 1987/1/1

Y1 - 1987/1/1

N2 - Differential cross section (DCS) measurements are reported for scattering of a He atomic beam by crossed beams of Ar, C2H2, CO 2, and OCS. Relative to the HeAr diffractive structure, the HeC 2H2 DCS is moderately damped at small scattering angles and severely damped at large scattering angles; the HeCO2 and HeOCS DCS's are severely damped for all scattering angles. This damping directly reflects increasing anisotropy of the scattering partner from Ar (none) to C2H2 (moderate) to CO2 and OCS (strong). Even though the present data do not resolve elastic from inelastic contributions, the HeCO2 results are consistent with partially resolved inelastic DCS measurements [U. Buck, H. Meyer, M. Tolle, and R. Schinke, Chem. Phys. 104, 345 ( 1986) ] and therefore complement them. Consequently the data are used to obtain empirical anisotropic intermolecular potentials for HeC2H 2 and HeOCS within the infinite-order-sudden approximation. These reproduce the total (unresolved elastic + inelastic) DCS measurements very well, even though the angular asymmetry of OCS is ignored in the analysis.

AB - Differential cross section (DCS) measurements are reported for scattering of a He atomic beam by crossed beams of Ar, C2H2, CO 2, and OCS. Relative to the HeAr diffractive structure, the HeC 2H2 DCS is moderately damped at small scattering angles and severely damped at large scattering angles; the HeCO2 and HeOCS DCS's are severely damped for all scattering angles. This damping directly reflects increasing anisotropy of the scattering partner from Ar (none) to C2H2 (moderate) to CO2 and OCS (strong). Even though the present data do not resolve elastic from inelastic contributions, the HeCO2 results are consistent with partially resolved inelastic DCS measurements [U. Buck, H. Meyer, M. Tolle, and R. Schinke, Chem. Phys. 104, 345 ( 1986) ] and therefore complement them. Consequently the data are used to obtain empirical anisotropic intermolecular potentials for HeC2H 2 and HeOCS within the infinite-order-sudden approximation. These reproduce the total (unresolved elastic + inelastic) DCS measurements very well, even though the angular asymmetry of OCS is ignored in the analysis.

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Damping of total differential cross sections: Observations and empirical anisotropic potentials for HeC₂H₂ and HeOCS

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