Magnetic Circular Dichroism of the 'F Band in KF and Quenching of 'F'-Center Spin Polarization by Optical Pumping.

摘要

The magnetic circular dichromism *MCD) of the F absorption band in KF has been detected. The field and temperature dependence of the MCD signal yielded g about 1 and delta = - 3.2 plus or minus 0.4 meV for the orbital g factor and spin-orbit splitting of the excited state of the F center. The effect of unpolarized optical pumping on the MCD signal was investigated, with the result that at the maximum power level used about 10 to the 15th power photons/sec) approximately 75% of the signal was quenched. The data have have been interpreted using a simple model involving a small (efficiency epsilon approximately 0.01) spin-memory loss while the F center electron is in the excited state. The fact that the spin poloraization of the F center can be completely quenched if the pumping intensity is high enough is sufficient to explain the absence of a spin-dependent contribution to the magnetic circular polarization of the F-center emission observed by Fontana and Fitchen. (Author)