Pulsed EPR studies of polycrystalline cesium hexamethyl hexacyclen sodide

Abstract

The electron spin echo envelope modulation (ESEEM) technique of pulsed EPR spectroscopy has been used to measure weak133Cs hyperfine couplings to trapped electrons in polycrystalline cesium hexamethyl hexacyclen sodide. Two magnetically distinct groups of weakly coupled133Cs nuclei were found — one with an isotropic electron-nuclear hyperfine (Fermi contact) coupling of 0.34 MHz and the other with a contact coupling less than 0.1 MHz. Analysis of these data, by computer simulation, shows that the number of Cs nuclei that give rise to these interactions and their distance from the paramagnetic center is consistent with the hypothesis that the trapped electrons occupy vacant anion sites. The results indicate that the spread of unpaired electron spin density, along the axis formed by the “contact ion pair,” may be greater than that in the plane perpendicular to this axis.