AVS 46th International Symposium
    Surface Science Division Wednesday Sessions
       Session SS-WeP

Paper SS-WeP23
Low Energy Electron Damage to Condensed Phase Cyclic Ethers Studied by Electron Stimulated Desorption

Wednesday, October 27, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: L. Parenteau, University of Sherbrooke, Canada
Authors: L. Parenteau, University of Sherbrooke, Canada
D. Antic, University of Sherbrooke, Canada
L. Sanche, University of Sherbrooke, Canada
Correspondent: Click to Email
Low-energy electron (E@sub i@ < 20 eV) damage to condensed molecules prepared under ultra-high vacuum conditions has been the focus of intense study in recent years.@footnote1@ This research has particular relevance to the field of radiation science as it is well known that a large amount of low-energy secondary electrons are produced along the radiation tract following the interaction of ionizing radiation, the majority of which are created with initial kinetic energies well below 20 eV. At these low energies, fragmentation may occur following dissociative electron attachment (DEA) via the formation of negative ion resonances or by dipolar dissociation (DD). These processes are generally monitored in condensed-phase systems by electron stimulated desorption (ESD) which measures the negative ion yield desorbing from the surface. Below the DD threshold negative ion formation arises exclusively via DEA, whereas above this threshold the ESD yield is dominated by anions produced largely via DD. In recent years, there has been a shift in emphasis towards molecular systems of biological relevance, such as DNA bases,@footnote2@ radiosensitizing 5-halo-uracils and homo-oligonucleotides.@footnote3@ We are now studying the chemical consequences of the interaction of low energy electrons with the deoxyribose backbone of DNA and its constituents. Preliminary results on DEA damage to DNA sugar-like backbone analogues, tetrahydrofuran, 3-hydroxy-tetrahydrofuran and tetrahydrofurfuryl alcohol will be presented. In addition to a core excited resonance observed in the H@super -@ ESD yield near 10 eV incident electron energy, we find significant H@super -@ production via DEA to occur above the DD threshold for incident electron energies near 23 eV. @FootnoteText@ @footnote1@L. Sanche, Scanning Microscopy 9, 619 (1995). @footnote2@D.V. Klyachko, M.A. Huels, and L. Sanche, Radiat. Res. 151, 177 (1999). @footnote3@P.C. Dugal, M.A. Huels, and L. Sanche, Radiat. Res. 151, 325 (1999).