Luminescence from Mn-doped PbI2 crystals

Luminescent properties of PbI2 and PbI2: 0.5 mol % MnCl2 crystals under X-ray or N2-laser excitation are studied experimentally. The measurements are performed at temperatures ranging from 85 to 295 K. For PbI2 crystals under laser excitation, spectral bands with peaks near 495 and 512 nm, respectively, are observed at 85 K. With X-ray excitation at the same temperature, luminescence is observed in the 515-and 715-nm bands. The doping decreases the intensity in the 515-nm band, increases it for longer wavelengths, and shifts the highest peak to 700 nm. At 85 K, the doping has an insignificant effect on the excitation energy accumulated by trapped electrons. Certain PbI2 crystals also exhibit a peak in a region of 580–595 nm. This peak becomes much higher if the crystal is treated with an N2 laser at room temperature or if it is heated to 450–485 K. As the measurement temperature rises from 85 to 295 K, luminescence intensity decreases considerably. With X-ray excitation at room temperature, the yield of PbI2: Mn luminescence peaked at 660 nm for doped crystals is about three times larger than the yield peaked at 555 nm for nondoped crystals. The spectral curves and underlying radiative processes are discussed.