Fluorescence Spectra of Pyranine in Anodic Porous Alumina and Sol-gel Alumina

Anodic porous alumina films have been studied for many years and industrially used such as in capacitors, prevention and decoration of aluminum surface. Among them, dyeing of aluminum surface is of considerable interest from the view point of organic-inorganic nanocomposites, which can be applied to photonics materials: nonlinear optics, solid state dye lasers, electroluminescence, and biosensor. Therefore, it is necessary to well characterize the interactions between organic molecules and porous alumina for developing novel materials with better performance. However, so far, there has been less attention paid to organic molecules in anodic porous alumina. In this paper, pyranine(8-hydroxy-1,3,6-pyrene trisulfonate)molecules were used as a probe to study microenvironments of anodic porous alumina and sol-gel alumina. The fluorescence spectra of pyranine in those systems indicated the presence of the hydrophilic site and hydrophobic site in the alumina depending on the preparation conditions