0000000000172078
AUTHOR
J.-m. Spaeth
RbBr and CsBr doped with Eu2+ as new competitive X-ray storage phosphors
Abstract After X-irradiation of the alkali halides RbBr and CsBr doped with divalent Eu a significant photostimulated luminescence (PSL) effect was found. In both systems the electron trap centre is an F centre, the hole trap centre is still unknown. The Eu 2+ aggregation with cation vacancies plays an important role. Although all of the different Eu 2+ aggregates seem to show PSL effects, they have different PSL efficiencies, decay times and spectral characteristics. In the case of RbBr:Eu 2+ it was possible to investigate the different Eu 2+ -cation vacancy aggregate states by magnetic circular dichroism of the optical absorption (MCDA) and MCDA-detected electron paramagnetic resonance. I…
Magnetooptical studies of defects and recombination luminescence in LiBaF3
Abstract Optically detected EPR investigations have been performed on the recombination luminescence (RL-EPR) of LiBaF3 crystal, X-irradiated at T=4.2 K . RL-EPR lines of VK- centres were found, as well as further lines of a defect with S= 1 2 and an axial g-tensor with its main axis along a [1 0 0] direction of the crystal. Measurements of the magnetic circular dichroism of the absorption (MCDA) have been performed on LiBaF3 crystals X-irradiated at two temperatures ( 4.2 K and RT). After irradiation at T=4.2 K , the main MCDA bands peak at 453 and 500 nm , but after irradiation at T=300 K , the main bands peak at 444 and 390 nm , there is a change of the sign between the peaks in both cas…
Investigation of Oxygen-Related Luminescence Centres in AlN Ceramics
The structure of oxygen-related luminescence centres in nominally undoped and Y 2 O 3 doped AlN ceramics was investigated by electron paramagnetic resonance (EPR), electron nuclear double resonance (ENDOR) and optically-detected EPR. The photoluminescence-detected EPR lines having g-values of 1.990 and 2.008 were assigned to a recombination between neighbouring donor and acceptor pairs. The two EPR lines at g = 1.987 and 2.003 detected via the recombination luminescence in the afterglow are thought to be due to a recombination between the same, but distant donor and acceptor pairs. The donor was previously speculated to be an electron trapped on an oxygen impurity which substitutes for a ni…
Radiation-induced defects and their recombination processes in the x-ray storage phosphor BaBr2:Eu2
The recombination processes in the x-ray storage phosphor BaBr2:Eu2+ were investigated by optical and magneto-optical methods. A structure-sensitive investigation of the defects involved in the recombination processes was performed by detecting the microwave-induced changes in the recombination luminescence in a high magnetic field. F centres as well as VK hole centres are created after x-irradiation at low temperatures. The low-energy recombination band peaking at about 460 nm is due to F–VK centre recombinations, whereas the two high energy bands at 282 and 315 nm are probably due to recombinations of self-trapped excitons.
Optical and magneto‐optical studies of Mn‐activated LiBaF 3
The photoluminescence (PL) of Mn-doped LiBaF3 shows a weak Mn2+ emission band at 710 nm; the corresponding excitation bands are between 210 and 620 nm. After X-irradiation the PL spectrum shows two new bands peaking at 600 and 670 nm that are tentatively assigned to perturbed Mn2+ emissions; the intensity of all PL bands is increased. Magnetic circular dichroism (MCD) and the MCD-detected electron paramagnetic resonance (EPR) measurements show that F-type centres are formed after X-irradiation. The EPR measurements indicate that there is a spatial correlation between the F-type centre and the Mn2+ dopant. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)