[Back]

S. Li, Y. Losovyj, V. Paliwal, U. Diebold:
"Photoemission Study of Azobenzene and Aniline Adsorbed on TiO_{2} Anatase (101) and Rutile (110) Surfaces";
Journal of Physical Chemistry C, 115 (2011), 10173 - 10179.

ABSTRACT: The electronic structure of azobenzene and aniline,
adsorbed on two TiO2 surfaces, anatase (101) and rutile (110), has
been studied with ultraviolet synchrotron-based photoemission
spectroscopy (UPS). At saturation coverage, azobenzene and
aniline exhibit very similar molecular orbitals in UPS valence band
spectra. Angle-resolved UPS exhibits anisotropy of the molecular
states along the polar and azimuthal direction, as is expected for
highly oriented superstructures. For a low coverage of azobenzene
adsorbed on anatase, photon irradiation results in the conversion of
the #at-lying molecule into two upright phenyl imide species. An irradiation-induced trans!cis isomer conversion is proposed to
facilitate the azobenzene cleavage. These results con"rm that the NdN double bond of azobenzene is cleaved by TiO2 in the fullcoverage
regime and that the resulting intermediate is bonded to the substrate, in agreement with a previous scanning tunneling
microscopy study and a proposed reaction scheme for azobenzene T aniline conversion at TiO2 surfaces [Li, S.-C.; Diebold, U. J. Am. Chem. Soc. 2010, 132, 64].