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Isotope effects in abstraction and exchange reactions H + H′Br
Author(s) -
Hepburn J. W.,
Klimek D.,
Liu K.,
Macdonald R. G.,
Mayne H. R.,
Northrup F. J.,
Polanyi J. C.
Publication year - 1981
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550130908
Subject(s) - chemistry , atom (system on chip) , kinetic isotope effect , isotope , abstraction , potential energy surface , cross section (physics) , molecule , atomic physics , deuterium , nuclear physics , physics , organic chemistry , philosophy , epistemology , quantum mechanics , computer science , embedded system
A preliminary report is given of relative reactive cross sections for four abstraction reactions H + H′Br ← HH′ + Br with attacking atom (A) H or D, and atom under attack (B) H or D. The pattern of reactive cross sections, as obtained in a crossed molecular beam experiment at a collision energy E T = 7 kcal/mol, indicates S r (D,H) ≤ S r (D,D) > S r (H,H) > S r (H,D). The atoms in parentheses are A and B. We describe a three‐dimensional classical trajectory (CT) study on a potential‐energy surface proposed in 1969 by Parr and Kuppermann (PK); the CT results are in fair accord with experiment. It is suggested that (D,H) has the largest cross section because it exhibits the most favorable relative timing of A approach to BC rotation. On the basis of CT it appears that the same sequence of cross sections and the same rationale may be applied to the exchange reactions H + BrH′ ← HBr + H′.