UV Radiation Effects on SiO2 Gels Doped with Organic Dyes |
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Authors: | J. M. Garcia V.M. Castaňo M.A. Mondragón E. Ramírez F. González A. Campero V. Rentería |
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Affiliation: | (1) Instituto de Física, UNAM, P.O. Box 20-364, 01000 México, D.F.;(2) Departmento de Química, UAM (Iztapalapa), P.O. Box 55-534, 09340 México, D.F. |
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Abstract: | Silica gels prepared by the sol-gel method with TEOS as a precursor and doped with the organic dyes rhodamine B, Na fluoresceine and eosine G were exposed to UV radiation pulses from a nitrogen laser. The absorption, luminescence and IR spectra were taken as a function of the exposure time. The absorption and the luminescence curves show successive maxima and minima. The same response is observed when the exposure procedure is repeated. These results are explained in terms of the cyclic filling and depletion of the long-lived triplet excited electronic state. At short exposure times, the data can be fitted with a Lorentzian curve and the corresponding parameters are given. |
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Keywords: | UV irradiation dye laser gels luminescence organic dyes |
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