Fabricação e caracterização de filmes finos e ultrafinos de coroas de éter com azobenzeno incorporado e estudo da birrefringência fotoinduzida
2008; Linguagem: Inglês
ISSN
2639-6459
Autores Tópico(s)Photochemistry and Electron Transfer Studies
ResumoLangmuir monolayers, Langmuir-Blodgett (LB) films and thin filmes prepared by casting (auto standing films) from a series of azocrown ethers molecules were studied. Films were characterized using UV-Vis and FTIR spectroscopy and Raman scattering techniques. The compound 29-diazocrown ether with two n-octyl substituent was the only azocrown ether molecule that allowed us to prepare high quality LB films having suitable optical properties for photo induced birefringence studies. On birefringence measurements using LB films and auto standing films of the 29-diazocrown ether several experimental parameters were varied: number of monolayer of LB films, thickness of the auto standing film, excitation light intensity and temperature. It was found for the dynamics of formation and decay of the birefringence is much faster for LB films when compared with the auto standing films. The experimental curves of birefringence signals for LB films were fitted using the Debye and Kohlrausch-Williams-Watts (KWW) functions while the experimental curves for the auto standing films were fitted using the Sekkat and KWW functions. From the obtained time constants of fittings the Arrehnius activation energy and the dynamics of the formation and decay of the birefringence for the films were compared and discussed.
Referência(s)