RES structure of Bi³⁺ centres in KCI: Bi, S and CaO:Bi crystals

Abstract

Emission, excitation, and polarization spectra as well as decay kinetics are studied at 4.2 to 500 K for the luminescence of BC' + centres in two crystals (KC1 and CaO) with strongly different electron-phonon interaction. It is concluded that three bands at -2.5, 3.11, and -1.5 eV, observed in the emission spectrum of the KC1 : Bi, S crystal belong to the same centre, but arise from states of different origin. The splitting of the 2.5 eV band, caused by the presence of a defect (S2-) near a Bi'+ ion is detected. Besides the well-known triplet 3.3 and 3.1 eV bands, a new 4.15 eV emission is found in CaO :Bi crystal, which is ascribed to transitions from the singlet excited state of the Bi3+ ion. The structure and the parameters of the relaxed excited states are determined and the models of the corresponding BiJt centres are discussed.

Origin of Bi3+‐related luminescence centres in Lu3Al5O12:Bi and Y3Al5O12:Bi single crystalline films and the structure of their relaxed excited states

“…Thus, the decay kinetics of the UV emissions of LuAG:Bi and YAG:Bi is similar to that observed for the triplet emission of Bi 3+ centers in some other hosts (see, e.g., [1,[9][10][11]). It can be described within the phenomenological model used in [1] for Bi 3+ centers in Y 3 Ga 5 O 12 .…”

Photoluminescence of Lu3Al5O12:Bi and Y3Al5O12:Bi single crystalline films

“…Comparison of the data obtained for YAG:Bi in the present paper and for LuAG:Bi by Babin et al (2009) with those reported for the UV emission of Bi 3þ centers in other hosts (see, e.g., Wolfert and Blasse, 1985;Donker et al, 1989;Aceves et al, 1996;Nikl et al, 2005) allows us to conclude that the 5.9 eV and 4.57 eV excitation bands arise from the electronic transitions to the singlet and The intensity of the UV band is decreased 10 times. The spectra are distorted around 2.7 eV due to the contamination of the samples with Ce 3þ ions and the reabsorption of the VIS emission in the z2.7 eV absorption band of Ce 3þ centers.…”

The luminescence of CaWO4: Bi single crystals

“…Thus, emission decay of from A X -minimum can be decomposited into two (fast and slow) components. The lifetimes of the A X -slow components of ns 2 -ions luminescence usually are of the order of micro-and even milliseconds at room temperature in AHC [12,19] and oxides [20]. So, observed magnitude of lifetime equal to 0.4-0.8 ms for the Bi 3+ ions emission in CaWO 4 :Bi and CdWO 4 :Bi [4,5] crystals at 300 K is the typical lifetime for the A X -luminescence of ns 2 -ions.…”

“…The 3 P 0 and 3 P 1 states form a double minimum in the configurational space due to the Jahn-Teller effect, labeled as A T and A X , [11,12,19]. Because radiative de-excitation of the A T -minimum to the ground 1 S 0 state is parity allowed (due to j-j coupling), the emission decay is rather short (typically in nanosecond range for Tl + , Pb 2+ and Bi 3+ ions in Alkali-Halide compounds (AHC) [12,19]). Luminescence from A X -minimum is the superposition of two processes: the j-j allowed emission, related to the 3 P 1 -1 S 0 transition, and slow process, related to depopulation of the 3 P 0 meta-stable level (the 3 P 0 -1 S 0 transition is strongly forbidden).…”