Comparative Study of Time-Dependent PAES and XPS on a Ni/Pd Surface

Abstract:

We report on time-dependent Positron annihilation induced Auger Electron Spectroscopy (PAES) study on 0.5 monolayers (ML) Ni on polycrystalline Pd accompanied by complementary X-ray induced Photoelectron Spectroscopy (XPS). The normalized PAES spectra showed a significant decrease in the Ni intensity and an increase in the Pd intensity as a function of time. To rule out varying influence on the elements e.g. from surface contaminates due to the residual gas, a time-dependent XPS analysis was performed on pure Ni and Pd as well as to analyze the main contaminants C and O. The O fraction was found to be constant within the measurement time and the time constants for C significantly differ from those of Ni and Pd in the PAES data. Consequently, it was concluded that the PAES data show a superposition of C contamination and structural changes at the surface of Ni/Pd.

• Periodical: Defect and Diffusion Forum (Volume 373)
• Pages: 313-316
• DOI: https://doi.org/10.4028/www.scientific.net/DDF.373.313
• Online since: March 2017
• Authors: Samantha Zimnik*, Christian Piochacz, Sebastian Vohburger, Christoph Hugenschmidt
• Keywords: Ni, Pd, Positron Annihilation Induced Auger Electron Spectroscopy (PAES), Surface Analysis, XPS

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