MCenters in MgF2Crystals

A study of the optical absorption and emission of the $M\left(C_{2h}\right)$ center in Mg${\mathrm{F}}_2$ has been made. It is shown that excitation of the 370-nm absorption band due to these centers gives rise to polarized emission bands at 420 and 861 nm. Narrow-line transitions are observed both on the low-energy side of the 370-nm absorption band and the high-energy side of the 420-nm emission band. These lines have almost a mirror symmetry about the zero-phonon line which occurs at 387.3 nm and are attributed to transitions involving the lattice vibration modes of the crystal.