Optical Study of CaF2:Ho+3

The spectral distribution of the thermoluminescent glow peaks at 155, 206, and 333°K and the room-temperature phosphorescence have been measured in Ca${\mathrm{F}}_2$: ${\mathrm{Ho}}^{+3\mathrm{}}$ following x irradiation. The emission comprises about sixteen lines between 5300 and 5600 Å, which arise from ${\mathrm{Ho}}^{3+}$ in sites of different symmetries. The relative intensities of groups of these lines change from peak to peak, which suggests that the compensator associated with the ${\mathrm{Ho}}^{+3\mathrm{}}$ ion becomes mobile at about room temperature.