Laser-flash-photolysis-spectroscopy: a nondestructive method?
Herein, we report the effect of the laser illumination during the diffuse-reflectance laser-flash-photolysis measurements on the morphological and optical properties of TiO2powders. A grey-blue coloration of the TiO2nanoparticles has been observed after intense laser illumination. This is explained by the formation of nonreactive trapped electrons accompanied by the release of oxygen atoms from the TiO2matrix as detected by means of UV-vis and EPR spectroscopy. Moreover, in the case of the pure anatase sample a phase transition of some TiO2nanoparticles located in the inner region from anatase to rutile occurred. It is suggested that these structural changes in TiO2are caused by an energy and charge transfer to the TiO2lattice.
Leibniz University Hannover, Institute for Technical Chemistry, 30167 Hannover, Germany. schneider@iftc.uni-hannover.de.
Jenny
J
Schneider
Konstantin
K
Nikitin
Ralf
R
Dillert
Detlef W
DW
Bahnemann