We present studies on the structure and chemical states of a catalyst developed by immobilizing palladium on S-terminated GaAs͑001͒. Hard x-ray photoelectron spectroscopy ͑HX-PES͒ of core-level and valence band photoemission consistently indicates that the organopalladium molecules are reduced on the surface yielding Pd nanoparticles with a metallic nature. This finding is supported by high-resolution observations using scanning electron microscopy and backscattered electron image. HX-PES results also reveal that a portion of S atoms forming the S-termination is oxidized during the formation of Pd nanoparticles.
In order to evaluate three peak detection algorithms, the influences of parameter values used were examined using digitized synthetic XPS spectra with different levels of noise. The three peak detection algorithms are the Threshold Curve of the Second Derivative (2nd DER method), the Directly Calculating Peak and Background Relations at a Candidate Peak (PB method), and the Rough Estimation of Spectrum Background (BGD method). The peak detection results clearly showed that particular combination of parameter values produce the best performance for each algorithm. The validity of those parameter values was assessed by comparing the results from the peak detection algorithms with those of visual detection. On the whole, the BGD method was found to be the most practical. The importance of choosing effective parameter values and the advantages and disadvantages of these three peak detection methods were summarized.
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