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Time dependence of the luminescence intensity in CdBr2 : AgCl,PbBr2 crystals under N2-laser excitation at room temperature

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Bolesta I. M. , Kalivoshka B. M. , Karbovnyk I. D. , Lesivtsiv V. M. , Novosad I. S. , Novosad S. S. , Rovetskyy I. M. , Velgosh S. R.

Materials Science Poland

2014

tom Vol. 32, No. 4

604--609

Results of optical-luminescence studies of polydoped photochromic CdBr2 : AgCl,PbBr2 crystals are presented. It is shown that the luminescence decrease vs. time under N2-laser excitation in the range of A-band of Pb2+ absorption is due to photochemical reactions. The empirical model describing the decrease of the luminescence related to silver impurities due to photochemical processes is suggested. Model parameters (trapping cross-section – σ – and the amount of centres destroyed by irradiation – β) were determined using the comparative analysis of experimental and calculated luminescence decay curves.

Monitoring Structural Transformations in Crystals. Part 10. Monitoring Molecular and Crystal Structures During a Yang Photocyclization Reaction – Comparative Studies

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Turowska-Tyrk I. , Łabęcka I. , Scheffer J. , Xia W.

2007

tom Vol. 81, nr 5-6

813-824

Structural changes in a crystal, brought about by the Yang photocyclization of the 2-(4-carboxybenzoyl)-2-methyl-endo-bicyclo[2.1.1]hexyl salt with (S)-(–)--phenylethylamine, were monitored by means of X-ray structure analysis. The changes taking place in the reaction centre, as well as changes inmolecular orientation and cell constants are discussed. Analysis of the geometrical parameters describing the reaction centre enabled an evaluation of the possibility of formation of the opposite enantiomer in a crystal. The results are compared with data for other intramolecular photochemical reactions.