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