Dynamics of the Optical-Pumping Cycle ofFCenters in Alkali Halides-Theory and Application to Detection of Electron-Spin and Electron-Nuclear-Double-Spin Resonance in the Relaxed-Excited State

The dynamics of the optical-pumping cycle of $F$ centers in alkali halides are governed by two prime factors: the large magnetic circular dichroism exhibited by the $F$ band and a large electron-spin memory over the entire cycle. A model of the pump cycle and associated rate equations are given. The most general solutions are given, and important special cases are treated in detail. A number of new experimental techniques are based on the special characteristics of the rate-equation solutions. Among these are purely optical techniques for measuring (i) the degree of spin memory in the entire pumping cycle and (ii) the spin-lattice relaxation rate in the relaxed-excited state (RES). But the most important new development based on the rate-equation solutions is the optical-trigger detection of both electron-spin resonance (ESR) and electron-nuclear-double-spin resonance of the RES. Results of these experiments, including ESR $g$ factors and hyperfine splittings for the RES are given and discussed.