AVS 55th International Symposium & Exhibition
    In Situ Microscopy and Spectroscopy: Interfacial and Nanoscale Science Topical Conference Wednesday Sessions
       Session IS+SY+SS-WeM

Invited Paper IS+SY+SS-WeM3
Medard W. Welch Award Lecture: Novel X-ray Photoelectron Spectroscopy Techniques for In Situ Studies of Surfaces in Equilibrium with Gases in the Torr Pressure Regime: Application to Catalysis and Environmental Sciences

Wednesday, October 22, 2008, 8:40 am, Room 310

Session: In Situ Spectroscopy – Interfacial Science and Catalysis
Presenter: M. Salmeron, Lawrence Berkeley National Laboratory
Correspondent: Click to Email

X-ray photoelectron spectroscopy (XPS) ideally suited to investigate the chemical nature of surfaces. Due to the scattering of eletrons by gas molecules XPS is in generally performed under high vacuum conditions. However, because of thermodynamic and/or kinetic limitations, the surface chemical state observed under vacuum is not necessarily the one under the pressures that are relevant to catalysis and the environment (Torr to atmosphere). We developed a electrostatic lens system combined with differentially-pumped chambers that permits operation at pressures of up to 10 Torr. I will describe this ambient pressure XPS apparatus and show recent applications to studies of oxidation and heterogeneous catalytic reactions. I will also show how the technique can solve and advance our fundamental knowledge of surfaces in environmental science studies, particularly in the presence of water vapor.