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Published on: September 26, 2016
A frequency-swept, longitudinal detection EPR system for measuring short electron spin relaxation times at ultra-low
Xueyan Tang1, Steven Suddarth1, Saurin Kantesaria1
1Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, 2021 6(th) Street SE, Minneapolis, MN 55455, USA.
Abstract:
A frequency-swept longitudinal detection (LOD) EPR system is described for ultra-low field spectroscopy and relaxometry. With the capability of performing simultaneous transmit and receive with -80 dB isolation, this LOD-EPR can capture signals with decay constants in the nanosecond range and in theory even sub-nanosecond range, at fields close to the earth's magnetic field. The theoretical principles underlying this LOD-EPR are based on a fictitious field that accounts for the Z-axis magnetization polarized by a radiofrequency field alone. The electron spin relaxation time is obtained directly from a previously derived equation that describes the relationship between the relaxation time and the spectral peak position. Herein, the first frequency-swept LOD-EPR system is described in detail, along with experimental measurements of the short relaxation time (∼30 ns) of the free radical, 2,2-diphenyl-1-picrylhydrazyl, at zero to low field.
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