Low-energy positron scattering from gas-phase pyrimidine: A quantum treatment of the dynamics and a comparison with experiments

J. Franz and F. A. Gianturco
Phys. Rev. A 88, 042711 – Published 24 October 2013

Abstract

In the present work we are reporting detailed quantum scattering calculations that describe the diffusion of a beam of low-energy positrons interacting with the pyrimidine target as a gas-phase partner. The calculations have employed an essentially ab initio model for the short-range correlation interaction and for the electrostatic interaction of an impinging positron and the electron+nuclear structure of the target molecule at its equilibrium geometry. The available experiments were also performed in the low-energy region below about 30 eV and have been reported by two different experimental groups cited in the main text. Those data include integral elastic plus rotationally and vibrationally summed cross sections, together with angular distributions over the same range of energies. The effects on the scattering observables which stem from the permanent dipole moment of the title molecule are carefully analyzed and computational corrections which ensure numerical convergence are introduced and discussed. The additional uncertainties introduced by the angular discrimination error present in the experiments are also discussed and analyzed, thereby providing a numerical procedure for correcting all available data. The final comparison between experimental angular distributions and the computed counterparts produced in the present work turns out to be very good. The same applies to the comparison in size and energy dependence of the integral cross sections, where we show that our calculated quantities and the corrected experiments are in very good agreement over the whole range of available energies.

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  • Received 25 June 2013

DOI:https://doi.org/10.1103/PhysRevA.88.042711

©2013 American Physical Society

Authors & Affiliations

J. Franz*

  • Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstr. 4-6, D-53115 Bonn, Germany

F. A. Gianturco

  • Department of Chemistry, The University of Rome Sapienza, Piazzale A. Moro 5, I-00185 Rome, Italy

  • *Present address: Department of Atomic, Molecular and Optical Physics, Faculty of Applied Physics and Mathematics, Gdansk University of Technology, ul. Narutowicza 11/12, PL 80-233 Gdansk, Poland; j.franz@ucl.ac.uk

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Vol. 88, Iss. 4 — October 2013

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