Luminescence from pure MnF2 and from MnF2 doped with Eu3+ and Er3+

Abstract

In this paper we report fluorescence measurements made over a range of temperatures on nominally pure and on Er- and Eu-doped Mn${\mathrm{F}}_2$. By studying the weak intrinsic fluorescence in nominally pure samples we can draw some conclusions about exciton decay and energy-transfer processes. The decay rate of the $E1\mathrm{}$ excitons is dominated by transfer to traps and depends strongly on temperature, exhibiting an activation behavior proceeding through a higher-$E2\mathrm{}$ state. In the rare-earth-doped crystals the optical excitation energy is shared between the Mn traps and the rare-earth ions. As the temperature is raised the excitation is redistributed between the rare-earth ions and the effective Mn traps leading to a temperature-dependent variation in the fluorescence spectra from these crystals.