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V. I. Feldman

Molecular mechanisms of selective effects in the radiation chemistry of organic and polymeric systems

Abstract

Physical and chemical grounds of selective effects in the radiation chemistry of molecular materials are considered. In order to determine specific “selection rules” at the early stages of the radiation-chemical processes in solid phase, the peculiarities of the behavior of ionized organic molecules were analyzed at different levels (“isolated molecule” – “molecule in environment” – “idealized molecular material” – “real system”). Recent experimental studies of the radiation-chemical transformations of organic molecules in rigid inert matrices with various physical characteristics are reviewed. The results of these studies have demonstrated high selectivity of deprotonation of the primary ionized molecules of oxygen-containing compounds in xenon matrices. It was found that the electronic characteristics of the inert matrices used (ionization potential, polarizability) had crucial effect on the reaction pathway for primary radical cations (up to complete switching between deprotonation and fragmentation channels). Model studies of the positive hole transfer between various molecules with close ionization potentials (“two-trap experiment”) made it possible to reveal the role of “fine tuning effects’ (in particular, molecular conformation) in the hole localization. The role of selective effects in the radiation chemistry of macromolecules and organized polymeric systems was discussed.
Moscow University Chemistry Bulletin.
2001, Vol. 42, No. 3, P. 194
   

Copyright (C) Chemistry Dept., Moscow State University, 2002
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