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27 results on '"Pawlik, Th"'

1. Investigation of the x-ray storage phosphors Cs2NaYF6:Pr3+ or Ce3+

Author

Pawlik, Th. and Spaeth, J.-M.

Subjects
Phosphors -- Research, Radiography -- Equipment and supplies, Physics
Abstract

The electron paramagnetic resonance and the electron nuclear double resonance spectra of x-ray storage phosphors Cs2NaYF6:Ce3+ and Pr3+ are used to analyze properties of the said crystals, particularly their storage and read out process. Results show that the photostimulable electron center of the phosphors is an F center. In x irradiation cases, only F centers and Pr4+ are involved in information storage and readout.

Published
1997

21. DEFECTS IN THE SILVER HALIDE PHOTOGRAPHIC PROCESS.

Author

Pawlik, Th. D., Eachus, R. S., Baetzold, R. C., Mcdugle, W. G., and Olm, M. T.

Subjects
*PHOTOGRAPHIC film, *ORGANOMETALLIC compounds, *LIGANDS (Chemistry), *ELECTRONIC structure, *HETEROCYCLIC compounds
Abstract

The imaging efficiency of today's photographic film and paper is influenced in a variety of ways. Among them, the incorporation of dopants is widely used to increase efficiency, control contrast or improve imaging deficiencies such as reciprocity law failure. Transition metal-organic ligand dopants are attractive because the organic ligand influences the photographic properties. Experimental studies have shown that many of these dopants incorporate well into the silver halide microcrystal even with large organic ligands. In this paper, experimental and computational results are presented on a variety of Ir-OL dopants in AgCl where OL is a small nitrogen and/or sulfur-containing heterocycle. Electron paramagnetic resonance methods provide information about the electronic structure, electron trapping properties and the stability of the electron trap state. These results are complemented by ab initio studies that give information about the optimum structure, charge compensation and the possibility of electron and hole trapping. [ABSTRACT FROM AUTHOR]

Published
2002
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25. Investigation of Radiation-Induced Defects in NaBr:Sr<SUP>2+</SUP>

Author

Molina, M.I. Grasa, Pawlik, Th., and Spaeth, J.-M.

Abstract

An EPR/ENDOR study of two radiation-induced defects in NaBr doped with Sr2+ is presented. X-irradiation at room temperature produces a large amount of F centres compared to undoped NaBr and an impurity-related hole centre of Br—2-type. An ENDOR investigation of the F centre yielded the superhyperfine interaction constants for the first two shells of neighbours. The Br—2-type hole centre has properties very similar to the H〈100〉DD centre in KCl:Sr2+. In contrast to the centres in KCl, which decay thermally at 255 K, the HDD centre in NaBr is stable at room temperature.

Published
1997
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