Emission decay kinetics in a CaWO4 : Bi crystal

• The decay kinetics of the 2.88 eV emission of pure and Bi-doped CaWO4 crystals has been studied in the temperature region of 4.2-300 K. The decay components connected with the radiative transitions from the triplet excited states of regular WO42- oxyanionic complexes and WO42- complexes perturbed by Bi3+ ions (WO42-(Bi3+) centres) have been identified. It is shown that WO4(Bi3+) centres can be excited directly above the edge of the fundamental absorption of CaWO4, or due to the energy transfer from the metastable state of a Bi3+ ion at the excitation in the Bi3+ absorption band at 4.4e.V. At temperatures T> 170 K, the excited state of the WO42-(Bi3+) centre is thermally ionised, giving rise to phosphorescence in the blue spectral region. These processes are compared with those known for excitons in PbWO4 crystals.

Subject headings

NATURVETENSKAP  -- Fysik -- Acceleratorfysik och instrumentering (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Accelerator Physics and Instrumentation (hsv//eng)

Keyword

emission decay kinetics

triplet states

CaWO4 : Bi

energy transfer

Publication and Content Type

art (subject category)

ref (subject category)