Interfacial Excited State Dynamics on TiO2
EMSL Project ID
24796
Abstract
Interfacial excited state dynamics (ESD) plays an important role in many chemical and biological processes. Specifically, interfacial ESD in TiO2-based materials, is critical to solar energy technology, catalysis, waste water treatments, and environmental clean-up. However, the microscopic mechanism of interfacial ESD is not well understood with regard to atomic surface structure, and material morphology. The goal of this proposal is to measure structurally-dependent electronic bulk and surface dynamics of electrons, holes, and excitons, on different but well-characterized TiO2 surfaces, using complimentary techniques. Scanning tunneling microscopy (STM) is capable of atomic spatial resolution but does not provide direct time-resolved data. PEEM is capable of femtosecond time resolution, and uses highly versatile photoemission detection, but has more limited spatial resolution. Laser desorption probes mechanistic details of excited state surface dynamics by probing kinetic energies of emitted atoms. Together, these interface specific and time- and spatially-resolved techniques provide a revealing window into the key dynamical factors controlling interfacial ESD and TiO2 photoactivity. Our experimental measurements will focus on excited state dynamics on various TiO2 surfaces, under ultra high vacuum conditions and at temperatures ranging from 10 to 350 K. The substrates will consist of single-crystal rutile samples of various crystallographic orientation and hence different (reconstructed) surface structures. We will also study rutile and anatase phases of TiO2 prepared using single crystals and thin films. To achieve femtosecond time resolution and atomistic spatial resolution, we will combine time-resolved photoemission electron microscopy and STM.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2007-07-01
End Date
2009-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members