title: Light-induced charge separation and storage in titanium oxide gels.
abstract: We report on the interaction of light with a particular class of media--wet gels, which in contrast to sols of nanoparticles possess a macroscopic bulk structure, and which differ from conventional solids by the existence of the internal liquid-solid interface. We show, taking an absorption cross section of trapped electrons from Safrany, Gao, and Rabani [J. Phys. Chem. B 104, 5848 (2000)], that a separation of charges with quantum efficiency as high as 46% appears under the band-gap irradiation of titanium oxide gels: electrons are stored in the gel network as Ti3+ centers, whereas holes are stored in the liquid phase. Under a prolonged UV-laser irradiation, more than 14% of Ti4+ centers can be converted into Ti3+ . Their lifetime can be extremely long and exceeds months at room temperature. The trapped electrons are responsible for a "dark" absorption continuum covering the spectral range from 350 nm to 2.5 mum .
authors.affiliation: Laboratoire d'Ingénierie des Matériaux et des Hautes Pressions, Centre National de la Recherche Scientifique, Institut Galilée, Université Paris--Nord, 93430 Villetaneuse, France.
authors.forename: A I
authors.initials: AI
authors.lastname: Kuznetsov
authors.forename: O
authors.initials: O
authors.lastname: Kameneva
authors.forename: A
authors.initials: A
authors.lastname: Alexandrov
authors.forename: N
authors.initials: N
authors.lastname: Bityurin
authors.forename: Ph
authors.initials: P
authors.lastname: Marteau
authors.forename: K
authors.initials: K
authors.lastname: Chhor
authors.forename: C
authors.initials: C
authors.lastname: Sanchez
authors.forename: A
authors.initials: A
authors.lastname: Kanaev