Fourier transform studies of electron spin echo modulation of hemoglobin azide

Abstract
Electron spin echo modulation studies of hemoglobin have been carried out at 4.2 K at x band. Samples have been prepared from human blood. The modulation has been analyzed in the frequency domain by Fourier transforming the time domain data. The analysis indicates that the modulation arises from 14N of the histidine and of the porphyrin. The superhyperfine frequencies obtained from the Fourier transform results have been interpreted in terms of quadrupole coupling, dipolar and contact coupling with 14N.