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AbstractAbstract
[en] A magnetic circular dicroism spectrometer is described, which was used in the following experiments: 1) The spin-lattice relaxation time (T1) for F centers in NaCl, NaBr, CsBr and CsCl, at 1,80K in magnetic fields up to 15000Gs is described. The suitability of the theory of ref. (08) to explain the differences observed for halides of differents alkali ions as well as for different structures is verified proves that the hyperfine interaction is the most important mechanism for this kind of centers. It is also verified that, for temperatures between 60K and 150K, T1 experimental values fits the theory of ref. (21) reasonably well, for F centers in KBr. This theory us an extension of that of ref. (8). 2) The MCD spectra for KCl:Co++ and Caf2:Co++ in different magnetic fields up to 56KGs, and in temperature range between 1,80K and 4,20K is obtained. The results are consistent with the assumption that Co++ centers are intersticial in KCl lattice
[pt]
Descreve-se um espectrometro otico para medidas de dicroismo circular magnetico (DCM), utilizado nas seguintes experiencias: 1) Medidas de tempo de relaxacao spin-rede (T1) para centros F em NaCl, NaBr e CsCl, a temperatura de 1,80K em campos magneticos ate 17000Gs. Verifica-se a validade da teoria da referencia (8) para explicar as diferencas observadas, no comportamento de T1, para halogenetos com diferencas ions alcalinos, bem como diferentes estruturas. Comprova-se que a interacao hiperfina ainda continua a ser o mecanismo mais importante para esses centros. Verifica-se tambem que, para temperaturas entre 60K e 150K, os valores de experimentais para T1 em KBr, concordam razoavelmente com a teoria da referencia (21). Esta teoria e uma extensao daquela da referencia (8). 2) Espectros de DCM para KCl: Co++ e Caf:Co++ foram obtidos para campos magneticos ate 56KGs e temperaturas entre 1,80K e 4,20K. Os resultados obtidos mostraram ser concordantes com a hipotese dos centros Co++ ocuparem sitios interticiais na rede de KClOriginal Title
Medidas magneto-oticas de tempos de relaxacao spin-rede em KBr e nos halogenetos de Na e Cs e estudo do dicroismo circular magnetico do ion Co++ em KCl
Source
1977; 122 p; Tese (Ph.D.).
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