Theoretical study of spin-temperature phenomena in EPR for the low-temperature approximation and steady-state conditions

Abstract

Using the concept of spin temperature in EPR in the low-temperature approximation and under steady-state conditions, we examine the dependence of the reciprocal spin temperature of the Zeeman subsystem and the dipole-dipole reservoir on the reciprocal lattice temperature in the presence of a saturating field. We show that more significant cooling of the dipole-dipole reservoir and heating of the Zeeman subsystem can be achieved than in the case of the high-temperature approximation. In the presence of a probe field, we study the conditions for the absorption to go to zero at the frequency of this field, as a function of the intensity of the saturating field and the frequency difference between the two fields. We show that the intensity of the saturating field increases as the frequencies of the fields come closer together, and goes to infinity when they coincide. This qualitatively corresponds to what we have in the case of the high-temperature approximation. The intensity of the saturating field has a minimum in the dependence on detuning of the frequency of the saturating field when the frequency of the probe field is fixed, as in the case of the high-temperature approximation. We can use this dependence to estimate the relaxation parameters.