Nonradiative energy transfer without lifetime quenching in doped Mn-based crystals

Abstract

It is generally considered that the introduction of acceptors into a crystal will result in a lowering of the luminescence output and lifetime of the host ions (the donors). In rare-earth-doped, Mn-based crystals, this is not the case. Although the luminescence output of the host Mn ions is significantly affected by the presence of the rare-earth ions, the luminescence lifetime of the Mn emission is relatively unaffected. In this study the systems investigated include ${\mathrm{MnF}}_{2}$, ${\mathrm{RbMnF}}_{3}$, ${\mathrm{RbMn}}_{0.8}$${\mathrm{Mg}}_{0.2}$${\mathrm{F}}_{3}$, ${\mathrm{RbMn}}_{0.4}$${\mathrm{Mg}}_{0.6}$${\mathrm{F}}_{3}$, ${\mathrm{RbMnF}}_{3}$:${\mathrm{Nd}}^{3+}$, and ${\mathrm{MnF}}_{2}$:${\mathrm{Er}}^{3+}$. Luminescence spectra, excitation spectra, and lifetime measurements over the 4--300-K range are presented to demonstrate the above behavior. A physical model is developed to explain the observed features, including the lack of quenching of the luminescence lifetime of the Mn ions. The analysis includes quantitative estimates of the activation energy for the quenching of Mn emission and the coupling strength between perturbed and unperturbed Mn ions.