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Femtosecond Dynamics of Norrish Type‐II Reactions: Nonconcerted Hydrogen‐Transfer and Diradical Intermediacy
Author(s) -
De Feyter Steven,
Diau Eric W.G.,
Zewail Ahmed H.
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/(sici)1521-3773(20000103)39:1<260::aid-anie260>3.0.co;2-r
Subject(s) - diradical , chemistry , intramolecular force , fragmentation (computing) , hydrogen atom , photochemistry , ketone , femtosecond , computational chemistry , stereochemistry , atomic physics , physics , organic chemistry , singlet state , laser , alkyl , computer science , optics , excited state , operating system
Norrish type‐II and McLafferty rearrangements , which both involve an intramolecular transfer of a γ H atom, can be differentiated on the femtosecond time scale. The McLafferty rearrangement results in ion fragmentation of the parent ketone, whereas the Norrish type‐II reaction leads to a diradical species, which then either cyclizes or fragments (see scheme). For Norrish type‐II reactions, the reaction time for the transfer of the hydrogen atom is within 70 – 90 fs, and the lifetime of the diradical intermediate is in the range of 400 – 700 ps at the total energy studied.