Analysis of Energy-resolved Density of Electron Traps for Characterization and Identification of Metal-oxide Particles

Here we propose a method for identification and characterization of metal-oxide powders with patterns of energy-resolved density of electron traps (ERDT) and conduction-band bottom (CBB) position, as a fingerprint, measured by newly developed reversed double-beam photoacoustic spectroscopy (RDB-PAS). Degrees of coincidence (ζ) of ERDT/CBB patterns could be quantitatively evaluated for a given pair of titania samples as a product of coincidence of (a) ERDT-pattern matching, (b) total density of electron traps, and (c) CBB position estimated by ordinary PAS. It was also shown that the higher the ζ is increased, the higher the degree of coincidence for photocatalytic activities of the pair of titania samples becomes regardless of three different photocatalytic reaction systems, presumably because photocatalytic activities are regulated by ERDT and CBB of titania powders.