K. Nitsch

Radiation induced formation of color centers in PbWO4 single crystals

The changes in the absorption spectra induced by Co60 irradiation and high temperature annealing was studied for selected PbWO4 crystals. Based on radiation and annealings induced absorption spectra, four color centers are proposed, which could be responsible for shaping the absorption spectrum of PbWO4 crystals below 3.6 eV, namely Pb3+, O−, F, and F+ centers. Thermoluminescence (TSL) glow curves above room temperature were also studied on these samples to determine further the trap levels resulting from irradiation. Correlation between the results obtained by TSL and Co60 irradiation induced absorption changes is discussed.

Efficient radioluminescence of the Ce3+-doped Na–Gd phosphate glasses

Photo- and radioluminescence, decay kinetics, and thermoluminescence are reported for a set of Ce3+-doped phosphate glasses. The presence of Gd3+ ions in the glass host matrix at concentrations above 20% enhances the energy transfer towards the Ce3+ emission centers, which results in a remarkable enhancement of the radioluminescence light output.

A study of electron excitations in and single crystals

The excitation spectra of photo- and thermo-luminescence were compared in the VUV - UV spectral region in and scheelite tungstates. Temperature dependences of emission intensities and decay times were measured for in the 80 - 300 K range and approximated by a simple phenomenological model. The energy level structure of the emission centre excited state and related kinetic processes are discussed for both tungstates.

Ternary alkali lead chlorides: Crystal growth, crystal structure, absorption and emission properties

Ternary alkali lead chlorides — KPb2C15, K2PbCl4, RbPb2C15, Rb2PbCl4, CsPbC13, KPbCl3 and Cs4PbCl6, are an important group of divalent lead compounds which, regarding the large concentration range of lead and its location in various crystal structures of these compounds, forms a very important model system for the investigation of the emission mechanism of divalent lead emission centers. This paper presents the basic information about these compounds as well as their purification and the results obtained in crystal growth. It deals with crystal structures of these compounds and their comparison with that of PbCl2. Great attention is paid to the study of absorption and emission properties of these compounds.

Decay kinetics and thermoluminescence of PbWO4 : La3+

Correlated measurements of emission spectra, photoluminescence and scintillation decays, thermoluminescence, and light yield were performed on a selected set of undoped and La-doped PbWO4 single crystals. The samples were grown from 5N purity raw powders and show the blue emission component only. Distinct influence of La doping was found in the decays, thermoluminescence and light yield characteristics. It is discussed in the light of the direct influence of La doping on suppressing the creation of point defect centers in the PbWO4 lattice, which are involved in the energy transfer and storage processes in this material.

Optical properties of Nd 3+ - and Tb 3+ -doped KPb 2 Br 5 and RbPb 2 Br 5 with low nonradiative decay

We report on the optical properties of Nd3+- and Tb3+-doped low-phonon-energy moisture-resistant host crystals, potassium lead bromide (KPb2Br5), and rubidium lead bromide (RbPb2Br5), including absorption, emission, and emission lifetime measurements as well as calculations of the multiphonon decay rate, Judd–Ofelt parameters, and radiative transition probabilities for relevant (laser) transitions in these crystals. The RE3+:MPb2Br5 (M=Rb, K) crystal is a promising candidate for long-wavelength infrared applications because of the low phonon frequencies and other favorable features.

Lead bromide and ternary alkali lead bromide single crystals — growth and emission properties

Abstract Single crystals of PbBr 2 , RbPb 2 Br 5 and CsPbBr 3 (20 mm in diameter and 50 mm long) were grown by the Bridgman method from starting materials purified by bromination with bromine and hydrogen bromide and by zone refining and were tested by measurements of the low-temperature exciton luminescence and decay kinetics. The emission of RbPb 2 Br 5 resembles that of PbBr 2 . Short (10–20 ps) decay times were found in CsPbBr 3 . The emission of all compounds tested is strongly influenced by defects and the exciton character from Frenkel to Wannier type going from PbBr 2 to CsPbBr 3 .

Influence of La3+-Doping on Radiation Hardness and Thermoluminescence Characteristics of PbWO4

(a) ENEA-INN/TEC, Via Anguillarese 301, S.Maria di Galeria, 00060 Roma, Italy (b) Institute of Physics, Cukrovarnicka 10, 16200 Prague, Czech Republic (c) INFN, Dept. of Physics, University of Roma 1, P. le A. Moro 2, Roma, Italy (d) SIT, Shonan Institute of Technology, Fujisawa 251, Japan (e) CRYTUR Preciosa a.s., Palackeho 175, 51119 Turnov, Czech Republic (f) KEK, National Laboratory for High Energy Physics, Tsukuba 305, Japan (g) INFM and Dept. of Physics, University of Milano, Via Celoria 16, 20133 Milano, Italy (h) Furukawa Co., Yoshima, Iwaki 970-11, Japan

Growth of lead tungstate single crystal scintillators

Abstract In this paper we present information on the growth of first-quality lead tungstate PbWO 4 single crystals and their luminescence and absorption properties. In comparison with so far presented PbWO 4 our single crystals show the prevailing blue emission component in radioluminescence at room temperature and fast scintillation decay in the nanosecond range with a very low level of slow processes on the micro-miliseconds time scale. These facts suggest that especially PbWO 4 single crystals with these properties are suitable as scintillating medium for a crystal calorimeter for the Large Hadron Collider project at CERN.

Photoluminescence of Cs4PbBr6 crystals and thin films

Abstract Absorption, emission and decay kinetics characteristics of Cs 4 PbBr 6 bulk and thin film samples were measured in the UV–visible spectral range over 4.2–250 K. An emission band at 375 nm was ascribed to the Cs 4 PbBr 6 structure itself with two excitation maxima round 310 and 240 nm coinciding with absorption peaks in the thin film absorption spectrum. The coexistence of Cs 4 PbBr 6 and CsPbBr 3 phases was evidenced in both the bulk and thin film systems.