Europhys. Lett.
Volume 48, Number 5, December 1999
Page(s) 519 - 525
Section Atomic and molecular physics
Published online 01 September 2002
DOI: 10.1209/epl/i1999-00515-8

Europhys. Lett, 48 (5), pp. 519-525 (1999)

Positron annihilation in $\rm CO_2$ molecules: The role of vibrational excitation

F. A. Gianturco and T. Mukherjee

Department of Chemistry, The University of Rome
Città Universitaria, 00185 Roma, Italy

(received 25 May 1999; accepted in final form 5 October 1999)

PACS. 34.50Gb - Electronic excitation and ionization of molecules; intermediate molecular states (including lifetimes, state mixing, etc.).
PACS. 34.80Bm - Elastic scattering of electrons by atoms and molecules.


In this work we discuss the theoretical and computational evaluation of the annihilation efficiency of positron beams when scattered by a molecular gas at room temperature. The present quantum treatment for the $\rm CO_2$ molecule explores the effects of the dynamical coupling between the target vibrations and the positron. The results show for the first time that such effects can play a role in enhancing $Z_{\rm eff}$ at the temperatures of the experiment.


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