Observation of Intrinsic Surface States at the TiO2 Aqueous-Electrolyte Interface by Sub Band-Gap Electroreflectance Spectroscopy

Abstract

Surface states were detected with sub?band-gap electroreflectance spectroscopy in the presence of electrolytes that can adsorb on the surface of TiO2. The energy of these states is located 1.3 eV below the conduction band and they can be detected only in the weak accumulation mode. The potential distribution at the interface as a function of the electrolyte was investigated by impedance spectroscopy. These results were interpreted in terms of "intrinsic" surface states of the unsolvated surface.