Formation of absorption and emission centres in PbWO ₄ surface layers induced by mechanical processing

Abstract

Radioluminescence and transmission spectra of PbWO 4 crystals manifest significant changes due to mechanical processing of crystal surfaces. Rebrushing and repolishing the surface of vacuum annealed Mo doped sample increases the green-luminescence intensity in more than one order of magnitude. A sample annealed in the atmosphere containing 1 ppm of O 2 shows after rebrushing a remarkable change in the 344 nm absorption band.

Structure of Centers of Matrix Emission of the Undoped and RE-Doped Scheelite-Type Lead Tungstate Crystals

“…The luminescence of the PWO compounds at low temperatures are presented by wide emission spectra covering the most of the visible range. The shapes, maxima positions, and intensities of these spectra depend on many factors such as the growth conditions, after-growth treatment, compositions and quality of reagents, presence of modifying impurities, and even the mechanical treatment of single crystal surfaces and the experiment conditions, e.g., the widths of optical slits [23][24][25]. Such behavior of the PWO emission is a result of the variations of relative contributions of several bands to the total spectrum.…”