Optical absorption and thermoluminescence of X-irradiated KDP

Optical absorption and thermoluminescence spectra of nominally pure X-irradiated KDP have been obtained between 13K and room temperature. Absorption spectra and their associated thermal bleaching curves exhibit a strong dichroism. Two glow peaks are observed at 73K and 123K which correlate well with main decay steps on the bleaching curve. From these data the existence of two different centres with activation energies of approximately 0.042 eV and approximately 0.22 eV is concluded. Different possibilities for the structure of these centres are discussed.