Luminescence of Er~(3+) ions in SrF_2 crystals under x-ray, ultraviolet and infrared excitation

摘要

Spectra of photoluminescence (PL) and X-ray excited luminescence (XRL) in region of 350 - 850 nm, PL excitation spectra in UV-VUV region (112 - 400 nm), thermally stimulated luminescence and absorption spectra were studied in SrF_2 crystals doped with Er~(3+) ions. Intra-configurational radiative f-f transitions were studied at room temperature, 90 and 8 K under excitation with energy E_(exc): a) in fundamental absorption region (E_(exc) ≥ E_g); b) in intracenter excitation region (E_(exc) < E_g); c) in infrared region (E_(exc) E_g) with using laser 980 nm diode as exciting photons (up-conversion processes). The probability of radiative transitions from excited states of the impurity Er~(3+) center depends on energy of exciting photons. Up-conversion luminescence was studied in temperature interval from 90 to 460 K. While changing the temperature, intensity of main transitions (~4S_(3/2) → ~4I_(15/2), ~4F_(9/2) → ~4I_(15/2)) changes. At high temperature (T > 387 K) a new low-energy transition 4I9/2 → 4I15/2 was detected. The presented results can be used as reference for spectroscopy of f-f radiation transitions in Er~(3+) ion in wide spectral range of exciting photons in crystals with fluorite-type structure.