24 April 1998 Probing photoinduced electron transfer reactions at semiconductor-liquid interfaces
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The electron transfer dynamics of 9-anthracene carboxylic acid bound to TiO2 nanoparticles in ethanol has been examined by a combination of transient absorption and time- resolved anistropy measurements. The results from these experiments show that the forward electron transfer reaction is very fast, <EQ 360 fs for anatase TiO2 and <EQ 1 ps for rutile TiO2. The back electron transfer reaction occurs on a slower time scale: 33 +/- 1 ps for the anatase particles and 54 +/- 1 ps for the rutile particles. The rate of the back electron transfer reaction for anatase TiO2 is also very sensitive to the addition of small amounts of water to the ethanolic solutions. For example, adding 1 percent water by volume decreases the average back electron transfer time from 33 ps to 20 ps. The water also produces a red-shift in the absorption spectra of the TiO2 particles. These observations show that the back electron transfer reaction is in the Marcus inverted region.
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Ignacio Martini, Ignacio Martini, Jose H. Hodak, Jose H. Hodak, Gregory V. Hartland, Gregory V. Hartland, } "Probing photoinduced electron transfer reactions at semiconductor-liquid interfaces", Proc. SPIE 3273, Laser Techniques for Condensed-Phase and Biological Systems, (24 April 1998); doi: 10.1117/12.306133; https://doi.org/10.1117/12.306133

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