Magnetic Nature of the Relaxed Excited State of <i>F</i> Centers and Spin Flipping Processes in the Optical Pumping Cycle

Abstract

The magnetic nature of the relaxed excited state (RES) of F centers and spin-flipping processes in the optical pumping cycle have been clarified by studying the magnetic circular polarization (MCP) of emission when the pumping light is modulated between right and left circular polarization at the frequency of (ω/2π). Paramagnetic component Δ p (ω) of MCP is found to be proportional to the spin polarization P * (ω) in the RES with a proportionality constant F p . From the analysis of the dependence of Δ p (ω) at particular frequencies on the pumping photon energy E p h , F p is estimated. Thus, the E p h -dependence of the net spin-mixing parameter ε t is determined. The values of F p and ε t are found to be smaller than those determined previously. The source of discrepancy is discussed. It is suggested that the spin-mixing in the non-radiative transition process is not neglected.