Ambient pressure X-ray photoelectron spectroscopy and its applications

During the past decade, the application of Ambient Pressure X-rayPhotoelectron Spectroscopy (APXPS) has been recognized as an important in situtool to study environmental and materials science, energy related science, and manyother fields. Several APXPS endstations are currently under planning or developmentat the USA and international light sources, which will lead to a rapid expansion ofthis technique. The present work describes the design and performance of a newAPXPS instrument at the Advanced Light Source beamline 9.3.2 at LawrenceBerkeley National Laboratory. This new instrument, Scienta R4000 HiPP, is a resultof collaboration between Advanced Light Source and its industrial partner VGScienta.The R4000 HiPP provides superior electron transmission as well asspectromicroscopy modes with 16 ?m spatial resolution in one dimension and angleresolvedmodes with simulated 0.5° angular resolution at 24° acceptance.Applications of APXPS have been also given in this work. In the first studythe APXPS and mass spectrometry have been utilized to investigate the CO and O2co-adsorption and the catalytic oxidation of CO on a Pt(110) surface under variouspressures of CO and O2 (up to 250 mTorr). Studies suggest that there is no surfaceoxide formation on Pt under our reaction conditions. However, CO oxidation in thispressure (<500 mTorr), O2 to CO ratio (<10), and temperature (150 °C) regime isconsistent with the Langmuir?Hinshelwood reaction mechanism. Second work wasto study early oxidation stages of NiTi shape memory alloys using APXPS andNEXAF. The role of the temperature on the formation of passivation layer on NiTiwas pointed out.