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Title: Surprisal analysis of classical trajectory calculations of rotationally inelastic cross sections for the Ar--N/sub 2/ system; influence of the potential energy surface

Journal Article · · J. Chem. Phys.; (United States)
OSTI ID:7147604

Rotationally inelastic Ar--N/sub 2/ scattering on two different empirical potential energy surfaces has been investigated by the classical trajectory method. For each potential surface, state-to-state rotational transition cross sections sigma/sub j//sub prime//sub j (E) have been calculated at five total energies E and several initial rotational quantum states j of the N/sub 2/. Results obtained from the two potentials differ significantly with respect to final rotational state distributions, but the total inelastic cross sections are very similar. Consideration of the moments of the rotational energy transfer leads to the conclusion that the potential surface of Kistemaker and de Vries is the preferred one to represent the Ar--N/sub 2/ interaction. A surprisal analysis of the computed cross sections has been carried out. At energies below approx. =3000 K, near-linear surprisal plots are obtained, as found earlier by Levine, Bernstein, Procaccia et al., thus confirming the exponential gap law of Polanyi, Ding, and Woodall for rotational relaxation. Complete cross section matrices (at a given E) can thereby be generated from a two-parameter surprisal fit of a single column of a sigma/sub j//sub prime//sub j matrix (or even from a classically derived first moment from the state j=0). As expected, the rotational surprisal parameter theta/sub R/ is essentially independent of j, but it shows a significant, positive E dependence and differs in magnitude for the two potentials. (AIP)

Research Organization:
Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506
OSTI ID:
7147604
Journal Information:
J. Chem. Phys.; (United States), Vol. 65:10
Country of Publication:
United States
Language:
English