The physical nature of the observed multi-exponential or stretched-exponential ET dynamics in the ensemble-averaged experiments, often associated with dynamic and static inhomogeneous ET dynamics, can be identified and analyzed by the single-molecule spectroscopy measurements. Single-molecule spectroscopy reveals statistical distributions correlated with microscopic parameters and their fluctuations, which are often hidden in ensemble-averaged measurements. The interfacial ET activity of individual dye molecules showed fluctuations and intermittency at time scale of milliseconds to seconds. The fluctuation dynamics were found to be inhomogeneous from molecule to molecule and from time to time, showing significant static and dynamic disorders in the dynamics. The inhomogeneous electron transfer rate due to the interaction between a dye molecule and the semiconductor surface depends on the chemical and physical nature of both dye molecule and the semiconductor.
Reference
-
Vishal G. Rao, Bharat Dhital, H. Peter Lu, "Single-Molecule Interfacial Electron Transfer Dynamics of Porphyrin on TiO2 Nanoparticles: Dissecting Interfacial Electric Field and Electron Accepting State Density Dependent Dynamics," Chem. Commun., 51, 16821-16824 (2015).
-
Vishal Govind Rao, Bharat Dhital, Yufan He, H. Peter Lu, " Single-Molecule Interfacial Electron Transfer Dynamics of Porphyrin on TiO2 Nanoparticles: Dissecting the Complex Electronic Coupling Dependent Dynamics," J. Phys. Chem. C., 118, 20209-20221 (2014).
-
Yuanmin Wang, Papatya C. Sevinc, Yufan He, H. Peter Lu, "Probing Ground-State Single-Electron Self-Exchange Across a Molecule-Metal Interface," J. Am. Chem. Soc., 133, 6989-6996 (2011).
-
Guo, Lijun; Wang, Yuanmin; Lu, H. Peter, "Combined Single-Molecule Photon-Stamping Spectroscopy and Femtosecond Transient Absorption Spectroscopy Studies of Interfacial Electron Transfer Dynamics," J. Am. Chem. Soc. 132, 1999-2004 (2010) (Cover page).
-
Yuanmin Wang, Xuefei Wang, and H. Peter Lu, "Probing single-molecule interfacial geminate electron-cation recombination dynamics,” J. Am. Chem. Soc. 131, 9020–9025 (2009).
-
Yuanmin Wang, Xuefei Wang, Sujit Kumar Ghosh, H. Peter Lu, "Probing single-molecule interfacial electron transfer dynamics of porphyrin on TiO2 nanoparticles," J. Am. Chem. Soc. 131, 1479-1487 (2009).