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
- 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  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 . 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.
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