Electron-spin memory and magnetic-circular-dichroic effects in the luminescence of F centers in KI, KBr, and KCl

Abstract

We have solved the rate equations of the optical pumping cycle of the $F$ center in the case of two spin-mixing parameters, ${\ensuremath{\epsilon}}_{+}$ and ${\ensuremath{\epsilon}}_{\ensuremath{-}}$. The solutions and the experimental results for the magnetic circular dichroism of the $F$-center emission are in complete agreement, and have allowed for the first time the measurement of the "anisotropy" of the electron-spin memory, i.e., $\frac{({\ensuremath{\epsilon}}_{\ensuremath{-}}\ensuremath{-}{\ensuremath{\epsilon}}_{+})}{({\ensuremath{\epsilon}}_{\ensuremath{-}}+{\ensuremath{\epsilon}}_{+})}$. This quantity will be very useful in order to clarify the role of the various processes responsible for the loss of the spin memory in the optical cycle. Moreover, from the rate equations we have been able to find the value of the polarization in the relaxed excited state, which is essential to calculate the spin-orbit splitting in emission.