Probing Single-Molecule Interfacial Electron Transfer and Diffusion Dynamics under Surface Plasmon Excitation

Peter H. Lu Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio, USA

We apply single-molecule high spatial and temporal resolved techniques to study the complex reaction dynamics associated with electron and energy transfer rate processes at Molecule-TiO2 nanoparticle interfaces.1-5 Combined single-molecule time resolved spectroscopy, femtosecond ultrafast spectroscopy, surface plasmon enhanced Raman spectroscopy, and electrochemical atomic force microscopy (E-Chem AFM) approaches are unique for heterogeneous and complex interfacial electron transfer systems because the static and dynamic inhomogeneities can be identified and characterized by studying one molecule at a specific nanoscale surface site at a time.1-5 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

  1. 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," Phys. Chem. C., 118, 20209-20221 (2014).
  2. Yuanmin Wang, Papatya C. Sevinc, Yufan He, H. Peter Lu, "Probing Ground-State Single-Electron Self-Exchange Across a Molecule-Metal Interface," Am. Chem. Soc., 133, 6989-6996 (2011).
  3. Guo, Lijun; Wang, Yuanmin; Lu, H. Peter, "Combined Single-Molecule Photon-Stamping Spectroscopy and Femtosecond Transient Absorption Spectroscopy Studies of Interfacial Electron Transfer Dynamics," Am. Chem. Soc. 132, 1999-2004 (2010) (Cover page).
  4. Yuanmin Wang, Xuefei Wang, and H. Peter Lu, "Probing single-molecule interfacial geminate electron-cation recombination dynamics,” Am. Chem. Soc. 131, 9020–9025 (2009).
  5. Yuanmin Wang, Xuefei Wang, Sujit Kumar Ghosh, H. Peter Lu, "Probing single-molecule interfacial electron transfer dynamics of porphyrin on TiO2 nanoparticles," Am. Chem. Soc. 131, 1479-1487 (2009).

hplu@bgsu.edu









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