Interfacial electron transfer energetics studied by high spatial resolution tip-enhanced Raman spectroscopic imaging
Final Report Abstract
Interfacial electron transfer (IET) plays an important role in many chemical and biological processes. Specifically, IET in dye sensitized TiO2-based solar energy conversion systems is critical to new energy technology and sciences. However, the microscopic mechanism of interfacial ET is not well understood with regard to molecule-surface structure and interaction, energy flow across the interface, and vibrational relaxation barrier of IET. This collaborative research effort involving the Lu group at Bowling Green State University (USA) and the Meixner group at Eberhard Karls University in Tubingen (Germany) focuses on microscopic mechanisms of IET for model systems of dye sensitized TiO2 nanocryostals and crystalline surfaces. Lu has established a strong program on IET dynamics and mechanism and Raman spectroscopy analysis of the IET energetics on dye-TiO2 nanoparticles; whereas Meixner has a cutting-edge near-field Raman spectroscopy technical program on singlemolecule Raman imaging on single crystal surfaces. This is a perfect match to study an important scientific problem of solar energy conversion with world-rate advanced technology. Over the last three-year funding period (2008-2011), we have made the following significant progresses in our research project: (1) Realized the first time optical imaging of single surface state from Nb-doped TiO2 single crystal surfaces. (2) Demonstrated tip-enhanced parabolic mirror optical microscopy for opaque TiO2 samples. (3) Distinguished the alizarin-Au charge transfer complexes and the physisorbed Alizarin via surface and tip-enhanced spectroscopy. (4) Imaged the semiconductor ‘shinning-edge’ effect and domain distributions via tipenhanced near-field spectroscopy. In addition, we have established a strong and interactive collaboration between Lu's and Meixner's labs.
Publications
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“Interfacial electron transfer energetics studied by high spatial resolution tipenhanced Raman spectroscopic imaging”, Angew. Chem., 50 (2011) A25 – A29
Xiao Wang, Dai Zhang, Yuanmin Wang, Papatya C. Sevinc, H. Peter Lu, Alfred J. Meixner
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“Simultaneous Spectroscopic and Topographic Near-Field Imaging of TiO2 Single Surface States and Single-Molecule Ground-State Interfacial Electron Transfer ”, Nano Lett. 11 (2011) 1490 – 1494
Papatya C. Sevinc, Xiao Wang, Yuanmin Wang, Dai Zhang, Alfred J. Meixner, H. Peter Lu
