Spin Dynamics and Establishing of Internal Quasi-Equilibrium in Dilute Paramagnetic Solids

Abstract

Abstract A brief review is given of the development and experimental verification of the two-temperature quasi-equilibrium concept as applied to EPR in dilute paramagnetic solids. Existing experimental data on spectral diffusion in a dipolar broadened EPR line and excitation transfer inside the electron dipolar reservoir are newly considered. The discussion is supplemented with theoretical arguments based on the concentration and cluster expansion techniques. Conditions and limitations of applicability of the two-temperature quasi-equilibrium model to electron spin systems with random distribution of paramagnetic centers are cleared up.