title: Monitoring N719 dye configurations on (1 x n)-reconstructed anatase (100) by means of STM: reversible configurational changes upon illumination.
abstract: We report experimental results concerning the STM imaging of cis-bis (isothiocyanate)-bis-(2,2'-bipyridyl-4,4'dicarboxylate)ruthenium(II)bis(tetrabutylammonium) dye (known as N719) adsorbed on a single crystal of anatase TiO(2)(100). The cleaning pretreatment, by sputtering and annealing, of TiO(2)(100) yields a reproducible (1 x n) surface reconstruction. Previous to dye deposition, TiO(2) was covered with one monolayer of 4-tert-butylpyridine (4-TBP) in ultrahigh vacuum (UHV) in order to protect the surface against air contamination. N719 was subsequently deposited by dipping the crystal into the dye solution. 4-TBP was removed partially in the solution and totally by heating the sample to around 285-300 degrees C in UHV. The images of the deposited 4-TBP on TiO(2)(100) revealed a complete surface coverage showing three modes of adsorption on TiO(2). The relatively uncomplicated desorption of 4-TBP enables the accommodation and chemisorption of most N719 molecules directly onto the TiO(2) surface. The STM imaging of N719 was affected, in a reversible way, by illumination, because the quality of the image changed after a few hours in the dark or under illumination conditions. The results presented herein are discussed in terms of changes in molecular configurations and in open circuit potentials.
authors.affiliation: Institution for Physical & Analytical Chemistry, Uppsala University, The Angström Laboratory, Box 259, SE-751 05 Uppsala, Sweden.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Zuleta
authors.forename: Shun
authors.initials: S
authors.lastname: Yu
authors.forename: Sareh
authors.initials: S
authors.lastname: Ahmadi
authors.forename: Gerrit
authors.initials: G
authors.lastname: Boschloo
authors.forename: Mats
authors.initials: M
authors.lastname: Göthelid
authors.forename: Anders
authors.initials: A
authors.lastname: Hagfeldt