EPR spin flip transitions in some metal dithiolenes

Abstract

Small line widths (ΔB_pp ≅ 0.25-0.40 mT) in the EPR spectra of ⁶³Cu²⁺ in the matrices of some transition metal dithiolenes permit the observation of not-so-easily realizable proton spin flip transitions even at room temperature and at low microwave power. These transitions, studied in four different lattices as a function of crystal orientation, microwave power and temperature, have been found to be from the protons of the counter ions and a few angstroms away from the unpaired electron-containing metal centre. It has been possible to identify the protons and estimate their distances from the metal centre by two different methods. A temperature-dependent evaluation of the distance parameters as well as the observation of the "double" and "triple" flips are reported. The differential saturation of the "main" and "satellite" (due to spin flip) lines studied by the CW saturation method has provided information on the mechanism of spin relaxation in these systems.