Modulation on positions of optical absorption bands in porous host/

Abstract

The optical absorption properties of porous host/ nanocomposites were investigated. The results show that for each optical reflection spectrum, four absorption bands () occur in the wavelength range 200 - 800 nm. The and bands are induced by the electronic transitions from the ground-state energy level to the excited-state energy levels: and is formed from splitting of ), respectively. The appearance of is closely related to the and ions. For porous host/ nanocomposites, which are formed by assembling the porous host with nano- particles, the positions of absorption bands can be modulated by means of pyrolysis of at different temperatures in air, reducing the samples in high purity and the size confinement of particles by voids in the host. With increasing pyrolysis temperature, a blue shift of the absorption bands appears and, inversely, a red shift of the absorption bands takes place when heating the samples in .