• Bruhwiler, P. A.
• Karlsson, P. G.
• Sandell, A.
• Uvdal, Per
• Henningsson, A.
• Siegbahn, H.
• Andersson, Martin
• Schnadt, Joachim

Abstract

Bi-isonicotinic acid (2,2'-bipyridine-4,4'-dicarboxylic acid) is an important ligand in the chemistry of organometallic devices. Here, the adsorption of a monolayer of the molecule on in situ-grown anatase TiO2 nanoparticles has been investigated by means of X-ray photoemission spectroscopy and X-ray absorption spectroscopy. The bonding geometry is determined to be 2M-bidentate. Furthermore, resonant core spectroscopies have been used to study the excited-state-dependent electron transfer from the core-excited molecule to the substrate. For an excitation to the lowest unoccupied orbital, the excited electron is localized on the molecule because of a core-excitonic effect. Excitation to the two following unoccupied orbitals leads to a charge transfer on a low-femtosecond time scale. This study shows that there is no essential difference in charge-transfer characteristics, compared to the case of adsorption on the rutile (110) surface, for states degenerate with the conduction band.

Topics

• nanoparticle
• impedance spectroscopy
• surface
• x-ray absorption spectroscopy
• organometallic