AVS 51st International Symposium
    Applied Surface Science Thursday Sessions
       Session AS-ThA

Paper AS-ThA5
High-Pressure X-Ray Photoelectron Spectroscopy for Catalysis Research and Environmental Science

Thursday, November 18, 2004, 3:20 pm, Room 210A

Session: Fuel Cell, Catalytic, and Nanomaterials Characterization
Presenter: H. Bluhm, Lawrence Berkeley National Lab
Authors: H. Bluhm, Lawrence Berkeley National Lab
D.F. Ogletree, Lawrence Berkeley National Lab
G. Ketteler, Lawrence Berkeley National Lab, Univ. of California
M. Haevecker, Fritz Haber Inst. of the Max Planck Society, Germany
A. Knop-Gericke, Fritz Haber Inst. of the Max Planck Society, Germany
E. Kleimenov, Fritz Haber Inst. of the Max Planck Society, Germany
D. Teschner, Fritz Haber Inst. of the Max Planck Society, Germany
E.L.D. Hebenstreit, Lawrence Berkeley National Lab
V.I. Bukhtiyarov, Boreskov Inst. of Catalysis, Russia
M.K. Gilles, Lawrence Berkeley National Lab
T. Tyliszczak, Lawrence Berkeley National Lab
R. Schloegl, Fritz Haber Inst. of the Max Planck Society, Germany
M. Salmeron, Lawrence Berkeley National Lab
D.K. Shuh, Lawrence Berkeley National Lab
Correspondent: Click to Email
High-pressure X-ray photoelectron spectroscopy is a versatile method for the study of gas/solid and gas/liquid interfaces. Recently two synchrotron-based high-pressure XPS spectrometers have been developed, one located at the Molecular Environmental Science beamline at the Advanced Light Source in Berkeley, the other operating at BESSY in Berlin. We have used these high pressure XPS instruments to investigate problems in environmental science and heterogeneous catalysis. In this talk we will discuss the influence of the gas phase on the XPS spectra. Since the incident X-ray beam does not only irradiate the sample surface but also the gas phase in front of the sample, gas phase XPS peaks appear alongside the surface peaks at sufficiently high pressures. The gas phase signal can be used to probe the composition of the gas in the volume in front of the sample and get information about, e.g. the conversion and yield in heterogeneous catalytic reactions. An important group of materials in environmental science are minerals, which are often insulators and therefore charge when irradiated by X-rays. However, the sample surface is discharged due to the ionization of the gas phase by the incident X-rays. The amount of this effect depending on gas pressure and composition will be discussed. We will also consider the proper referencing of the binding energy, and the FWHM of the gas phase peaks depending on gas pressure and work function of the surfaces in the vicinity of the probed gas phase volume. @FootnoteText@ The Advanced Light Source and this work are supported by the Director, Office of Science, Office of Basic Energy Sciences, Division of Materials Sciences and the Division of Chemical Sciences, Geosciences, and Biosciences of the U.S. Department of Energy at Lawrence Berkeley National Laboratory under Contract No. DE-AC03-76SF00098.