Energy States and Luminescent Processes in the ZnF2: Mn Phosphor

Single crystals of ZnF2: Mn have a single symmetrical thermoluminescent peak when excited by monochromatic radiation of wavelength 1800 to 2300 A. The electron trap responsible for this peak is a metastable state of the activator. Excitation occurs first to a higher excited state from which both the emitting and trapping states are accessible. With 1850 A excitation, transfer to the emitting state from the initial excited state is approximately 4 times as probable as transfer to the trapping state. Untrapping occurs by a monomolecular process modified by thermally activated retrapping from the state governing the rate of emission. Energy level diagrams are proposed for the states of Mn++ responsible for absorption emission and trapping.