Chemical analysis of the Au-Ag nanoaloys

The nanostructures of AuAg nanoalloys were prepared by sequential sputtering of gold and silver thin films.  Single layer thickness was usually 2.8 nm were deosted by magnetron sputtering method in a Ar plasma. As deposited layers were annealed in Ar atmosphere at 550 degress for 15 minutes. For XPS measurements five samples were selected: pure gold and pure silver nanostructures and with composition of 25%, 50 and 75% Au.  The Omicron NanoTechnology spectrometer with a 128-channel collector was used for measurements. XPS studies were performed at room temperature under a ultra-high vacuum conditions, around 10-9 mBar. The photoelectrons were excited by an Mg-Kα X-Ray source. The X-ray anode was operated at 15 keV and 300 W. The Omicron Argus hemispherical electron analyser with a round aperture of 4 mm was used for the analysis of the emitted photoelectrons. The binding energies were corrected using the background C1s line (285.0 eV). XPS spectra were analysed with Casa-XPS software using Shirley background subtraction and Gaussian–Lorentzian curve as the fitting algorithm.