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Accueil > Séminaires > Année 2011 > Séminaire I.Fabrikant (22 novembre 2011)

Séminaire I.Fabrikant (22 novembre 2011)

1Department of Physics and Astronomy, University of Nebraska - Lincoln, USA 2Department of Physics and Astronomy, The Open University, Milton Keynes, UK

par Secretariat - 4 novembre 2011 (modifié le 8 novembre 2011)

Recent progress in the theory of dissociative electron attachment : from diatomics to biomolecules

We present a summary of recent progress in theoretical studies of low-energy dissociative electron attachment (DEA) to halogen molecules and polyatomic molecules based on the resonance R-matrix theory. It explains many observed features in DEA cross sections including low-energy behavior, threshold resonances and cusps. It also gives description of the temperature dependence of the attachment rate coefficients. The theory was also applied to several molecules of biological interest : formic acid, glycine, thymine and uracil [1,2]. Particular outstanding features are sharp peaks in DEA cross sections for uracil and thymine, which are interpreted as vibrational Feshbach resonances. More recent calculations describe DEA to alanine, β-alanine, and α-, β- and γ-aminobutanoic acids. We also investigated isotope effect and the results confirm experimental findings [3] for deuterated uracil and thymine.

For practical applications to radiation damage, it is important to know how DEA processes are modified in condensed-matter environments. It is known that the long-range effects are significantly suppressed in this case. A particular interesting example is a suppression of the VFR effect in DEA to the CH3I molecule observed experimentally [4]. Recent calculations confirm that the cross section for DEA to the CH3I molecule physisorbed on a surface of the Kr film is reduced by an order of magnitude as compared to the gas phase DEA cross section.

[1] G. A. Gallup, P. D. Burrow, and I. I. Fabrikant, Phys. Rev. A 79, 042701 (2009).
[2] G. A. Gallup and I. I. Fabrikant, Phys. Rev. A 83, 012706 (2011).
[3] S. Denifl, S. Ptasinska, M. Probst, J. Hrusak, P. Scheier, and T. D. Maerk, J. Phys. Chem. A 108, 6562 (2004).
[4] E. T. Jensen and L. Sanche, J. Chem. Phys. 129, 074703 (2008).

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