Uncovering molecule-TiO2 interactions with nonlinear ...

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Stephen A. Miller, Brantley A. West, Anna C. Curtis, John M. Papanikolas, and Andrew M. Moran. Citation: J. ..... It is likely that little delocalization of the electronic.
Communication: Uncovering molecule-TiO2 interactions with nonlinear spectroscopy Stephen A. Miller, Brantley A. West, Anna C. Curtis, John M. Papanikolas, and Andrew M. Moran Citation: J. Chem. Phys. 135, 081101 (2011); doi: 10.1063/1.3631339 View online: http://dx.doi.org/10.1063/1.3631339 View Table of Contents: http://jcp.aip.org/resource/1/JCPSA6/v135/i8 Published by the AIP Publishing LLC.

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THE JOURNAL OF CHEMICAL PHYSICS 135, 081101 (2011)

Communication: Uncovering molecule-TiO2 interactions with nonlinear spectroscopy Stephen A. Miller,1 Brantley A. West,2 Anna C. Curtis,1 John M. Papanikolas,1 and Andrew M. Moran1,a) 1

Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA 2 Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA

(Received 6 July 2011; accepted 8 August 2011; published online 22 August 2011) Femtosecond transient grating experiments are used to investigate electronic structures and transport mechanisms in dye-sensitized nanocrystalline TiO2 films. This study examines two molecular sensitizers spanning the weak (a phosphonated Ruthenium complex) and strong (catechol) moleculeTiO2 coupling regimes. It is shown that strong molecule-TiO2 interactions give rise to photoinduced vibrational coherences at the interface between species. We suggest that the amplitudes of these coherences reflect the molecule-TiO2 coupling strength and signify the delocalization of excited state wavefunctions. © 2011 American Institute of Physics. [doi:10.1063/1.3631339] Knowledge of electronic structure and transport mechanisms in dye-sensitized semiconductors is motivated by their ubiquity in photoelectrochemical cells.1–3 One vital area of research aims to understand how molecule-semiconductor interactions influence the primary events initiated by light absorption (e.g., electron transfer, nuclear relaxation).4–13 Pioneering experimental work established

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