Interaction of two superhigh-frequency fields with the resonance system of electron spins

Within the framework of the concept of a spin temperature in a steady-state regime, the interaction with a resonance medium of two superhigh-frequency fields, one of which is saturating and the other of which is trial, is considered theoretically in the general case without using a high-temperature approximation. The case where the absorption of a resonance medium vanishes at the trial-field frequency is investigated in detail. This occurs with an intensity of the saturating field lower than in the case of a high-temperature approximation. This intensity is estimated in the second and third orders by the parameter ω₀β_z/2, where ω₀ is the resonance frequency of the transition, β_z=ħ/(kT_z), T_z is the Zeeman-subsystem temperature, ħ is the Planck constant, and k is the Boltzmann constant. It is shown that the cooling of the dipole-dipole reservoir is more considerable than in the case of a high-temperature approximation. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 4, pp. 492–495, July–August, 2000.