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Experimental methods in chemical engineering: Electron paramagnetic resonance spectroscopy‐EPR/ESR
Author(s) -
Bakker Martin G.,
Fowler Benjamin,
Bowman Michael K.,
Patience Gregory S.
Publication year - 2020
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.23784
Subject(s) - electron paramagnetic resonance , unpaired electron , spectroscopy , paramagnetism , pulsed epr , chemistry , radical , nuclear magnetic resonance , chemical physics , materials science , condensed matter physics , magnetic resonance imaging , organic chemistry , spin echo , physics , medicine , quantum mechanics , radiology
Summary Electron paramagnetic resonance (EPR) spectroscopy, also known as electron spin resonance spectroscopy (ESR), utilizes absorption of microwave radiation by unpaired electrons in a magnetic field. The interaction between the unpaired electron(s) and nearby magnetic nuclei helps identify paramagnetic species and can provide information about the motion of the molecule and the local polarity, pH, viscosity, concentration, and accessibility to other paramagnetic species. This mini‐review discusses the fundamental underpinnings of EPR needed to correctly interpret EPR spectra. We describe various types of EPR spectra encountered by chemical engineers, and use application examples drawn from the chemical engineering literature to illustrate the information available from the technique. Few chemical engineering departments or even chemistry departments have EPR instruments, which contributes to the significant barrier that prevents this being adopted as a routine measurement technique. However, in 2016 and 2017, Web of Science indexed 7000 articles that applied EPR spectroscopy. A bibliometric map categorized the keywords in four categories based on co‐occurrences: magnetic properties, films, and luminescence; crystal structure, complexes, and ligands; nanoparticles, oxidation, and degradation; and, systems, radicals, and H 2 O 2 .