Femtosecond transient grating experiments are used to investigate electronic structures and transport mechanisms in dye-sensitized nanocrystalline TiO(2) films. This study examines two molecular sensitizers spanning the weak (a phosphonated Ruthenium complex) and strong (catechol) molecule-TiO(2) coupling regimes. It is shown that strong molecule-TiO(2) interactions give rise to photoinduced vibrational coherences at the interface between species. We suggest that the amplitudes of these coherences reflect the molecule-TiO(2) coupling strength and signify the delocalization of excited state wavefunctions.
© 2011 American Institute of Physics