Luminescence of Er3+ Ions in SrF2 Crystals Under X-ray, Ultraviolet and Infrared Excitation.

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 SrF2 crystals doped with Er3+ ions. Intra-configurational radiative f-f transitions were studied at room temperature, 90 and 8 K under excitation with energy Eexc: a) in fundamental absorption region (Eexc ≥ Eg); b) in intracenter excitation region (Eexc < Eg); c) in infrared region (Eexc << Eg) with using laser 980 nm diode as exciting photons (up-conversion processes). The probability of radiative transitions from excited states of the impurity Er3+ 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 (4S3/2 → 4I15/2, 4F9/2 → 4I15/2) 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 Er3+ ion in wide spectral range of exciting photons in crystals with fluorite-type structure. [ABSTRACT FROM AUTHOR]