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Electron Spin Polarization and Time‐Resolved Electron Paramagnetic Resonance: Applications to the Paradigms of Molecular and Supramolecular Photochemistry
Author(s) -
Turro Nicholas J.,
Kleinman Mark H.,
Karatekin Erdem
Publication year - 2000
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/1521-3773(20001215)39:24<4436::aid-anie4436>3.0.co;2-x
Subject(s) - radical , electron paramagnetic resonance , photochemistry , chemistry , supramolecular chemistry , paramagnetism , spin polarization , molecule , pulsed epr , spectroscopy , chemical physics , nuclear magnetic resonance , electron , organic chemistry , magnetic resonance imaging , medicine , physics , spin echo , quantum mechanics , radiology
Most molecular and supramolecular organic photochemical reactions involve paramagnetic reactive intermediates (such as molecular triplet states, triplet radical pairs, and free radicals). In a number of cases these species are created with “anomalous” spin populations which are far from thermal equilibrium. Such paramagnetic species are said to be “spin polarized” and may be observed directly by time‐resolved electron paramagnetic resonance (TREPR). The TREPR technique can be applied to exploit spin polarization, which, in addition to providing an enormous signal to noise enhancement, also reveals the mechanisms involved in photochemical reactions. TREPR spectroscopy provides a means of tracking the reaction of radicals with molecules and the nonreactive interactions of radicals with other radicals in real time. The latter interactions provide a systematic investigation of supramolecular interactions of geminate radicals in micelles.