Probing Single-Molecule Interfacial Electron Transfer Dynamics of Porphyrin on TiO₂ Nanoparticles

Abstract

Single-molecule interfacial electron transfer (ET) dynamics has been studied by using single-molecule fluorescence spectroscopy and microscopic imaging. For a single-molecule zinc-tetra (4-carboxyphenyl) porphyrin (ZnTCPP)/TiO(2) nanoparticle system, the single-molecule fluorescence trajectories show strong fluctuation and blinking between bright and dark states. The intermittency and fluctuation of the single-molecule fluorescence are attributed to the variation of the reactivity of interfacial electron transfer. The nonexponential autocorrelation function and the power-law distribution of the probability density of dark times imply the dynamic and static inhomogeneities of the interfacial ET dynamics. On the basis of the power-law analysis, the variation of single-molecule interfacial ET reactivity is analyzed as a fluctuation according to the Levy statistics.

Light-driven water oxidation for solar fuels

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Photophysical Behaviors of Single Fluorophores Localized on Zinc Oxide Nanostructures

“…Sensitization of semiconductor nanostructures by organic dye molecules has also been studied for use in solar photovoltaic devices [1–4]. Semiconductors with a wide band gap are sensitized to visible light by surface-adsorbed dye molecules and charge transfer process occurs from dye molecules to the conduction band of the semiconductor [1,5–7]. Examples of ZnO applications include short wavelength light-emitters, field-emitters, luminescence, and UV lasers [8–12].…”

Single-molecule chemical reaction reveals molecular reaction kinetics and dynamics

“…As for the chemical reactions in condensed phase, much less has been done about the molecular reaction dynamics due to the complexity of traditional methods 5,6 . Recent advances in single-molecule fluorescence microscopy have allowed the observations of individual molecules, such as their translational diffusion 7,8 , rotational diffusion 9 , spectral fluctuation 10 , conformational motion 11 , the studies of single enzyme or single nanoparticle catalysis [12][13][14][15][16][17] , and the distinguishing of alternative reaction pathways 18 . Single-molecule measurements can reveal the distributions of molecular static or dynamic properties in inhomogeneous system 19 .…”