Zeitschrift für Physik D Atoms, Molecules and Clusters

ISSN: 0178-7683 (printed version)
ISSN: 1431-5866 (electronic version)

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Abstract Volume 39 Issue 1 (1997) pp 59-67

Cross sections for rotational excitations of CH₄, SiH₄, GeH₄, SnH₄ and PbH₄ by electron impact

Márcio T. N. Varella (1), Márcio H. F. Bettega (2), Marco A. P. Lima (1)

(1) Instituto de Física Gleb Wataghin, Universidade Estadua de Campinas, UNICAMP, 13083-970 Campinas, São Paulo, Brazil
(2) Departamento de Física da Universidade Federal do Paraná, Caixa Postal 19081, 81531-990 Curitiba, Paraná, Brazil

Received: 14 March 1996/Final version: 25 June 1996

Abstract. We report differential and integral cross sections for rotational excitation of XH₄ molecules (X: C, Si, Ge, Sn, Pb) from 7.5-30 eV by electron impact. These cross sections were derived from fixed-nuclei scattering amplitudes (Bettega et al. 1995) obtained using the Schwinger Multichannel Method with Pseudopotentials (SMCPP) (Bettega et al. 1993). Our results represent the first rotational excitation cross sections for molecules as large as GeH₄, SnH₄ and PbH₄ using entirely ab initio procedures. The cross sections for CH₄ and SiH₄ obtained with pseudopotentials are in very good agreement with all-electron calculations and with other theoretical results. A comparison between our calculated cross sections and experimental data for CH₄ is in general encouraging, but some discrepancies remain. We found inelastic rotational cross sections and momentum transfer cross sections to be larger for SiH₄, GeH₄, SnH₄ and PbH₄ than for CH₄. We could explain this feature.

PACS: 34.80.Bm; 34.80.Gs

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