Photoluminescence studies on gray tracked KTiOPO4 single crystals

The photochromic, electrochromic and x-ray irradiation damages (commonly ca lled the gray tracks) produced in KTiOPO4 single crystals have been studied using photoluminescence (PL) spectroscopy. Gray tracks were produced in th is material by exposure to high laser powers (similar to MW/cm(2)), applica tion of electric fields (similar to kV), and exposure to x rays (30 kV). Th e PL spectra recorded for such gray tracked samples at 4.2 K, exhibited a l uminescence band in the 1-1.8 eV range with a peak at 1.41 eV. Temperature and excitation intensity dependence of PL peaks were carried out to probe t he exact nature of the broad emission band in the gray tracked samples. The observed photoluminescence is attributed to transitions in the Ti3+ levels , created on irradiation. The microscopic effects produced in the crystal b y electric field, optical field, and x rays are similar, as can be conclude d from the similarity of PL spectra as well as their intensity and temperat ure dependences. (C) 1999 American Institute of Physics. [S0021-8979(99)045 12-0].