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Electron Spin Echo Modulation Studies of Dipolar Hyperfine Interactions of Catalytic Reaction Intermediates Involving Transition Metal Ions on Oxide Surfaces
Author(s) -
Kevan Larry
Publication year - 1989
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.198900004
Subject(s) - chemistry , catalysis , electron paramagnetic resonance , hyperfine structure , ethylene , photochemistry , ethylene oxide , molecule , transition metal , environmental scanning electron microscope , oxide , reaction intermediate , metal , inorganic chemistry , nuclear magnetic resonance , organic chemistry , electron microscope , atomic physics , copolymer , physics , polymer , optics
The application of electron spin echo modulation (ESEM) pulsed electron spin resonance methods to detect dipolar hyperfine interactions of catalytic reaction intermediates involving transition metal ions on oxide surfaces is described. This provides a method to determine critical aspects of the geometrical structure of such intermediates. One example involves catalysis of ethylene dimerization by paramagnetic Ni + on silica. ESEM results show direct coordination of two and three ethylene molecules to Ni + as reaction intermediates in ethylene dimerization, depending on the activation temperature of the catalyst pretreatment. A second example involves catalysis of ethylene dimerization by paramagnetic Pd + in X—zeolite. ESEM results show direct coordination of successively one and two molecules of ethylene to Pd + prior to dimerization. Thus ESEM methods provide a powerful tool to develop a molecular picture of the course of catalytic reactions on surfaces.