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Updated: Jun 15, 2026

Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters In Vivo
Published on: September 26, 2016
Combining absorption and dispersion signals to improve signal-to-noise for rapid-scan EPR imaging
Mark Tseitlin1, Richard W Quine, George A Rinard
1Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA.
Abstract:
Direct detection of the rapid-scan EPR signal with quadrature detection and without automatic frequency control provides both the absorption and dispersion components of the signal. The use of a cross-loop resonator results in similar signal-to-noise in the two channels. The dispersion signal can be converted to an equivalent absorption signal by means of Kramers-Kronig relations. The converted signal is added to the directly measured absorption signal. Since the noise in the two channels is not correlated, this procedure increases the signal-to-noise ratio of the resultant absorption signal by up to a factor of square root 2. The utility of this method was demonstrated for 2D spectral-spatial imaging of a phantom containing three tubes of LiPc with different oxygen concentrations and therefore different linewidths.
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