X-ray photoelectron spectrometer (PHI Versaprobe)
In March 2022 PHI Versaprobe 3 AD spectrometer (PHI, Chanhassen, US) which is partially owned by our department was installed at the National Institute of Chemistry (NIC, Ljubljana). The system is equipped with pumps, valves, and load-lock to maintain ultra-high-vacuum conditions in the main chamber. X-Ray photoelectron spectroscopy is a surface-sensitive technique for analyzing the topmost 5 nm of the sample. In our system, a monochromated Al-Kα x-ray source with spatial resolution as low as 10 µm is used for irradiating solid sample surfaces that can be either conductive or non-conductive. Apart from standard XPS equipment, two ion guns are connected to the main chamber. Argon ion gun is used for sputtering of inorganic materials and neutralization of floating samples, while we use an argon gas cluster ion beam gun (GCIB) for soft sputtering of organic materials or removing residual carbon from the samples. Heating (max. 800°C) and cooling (min. -196°C) of the sample stage are also available. Angle-resolved measurements are possible in order to analyze near-surface regions. X-ray source can be switched to an ultraviolet source in order to probe valence states instead of core states. XPS system is connected to the glove box that allows the transfer of samples, sensitive to oxygen or moisture. The system also allows vacuum transfer from other vacuum systems (PLD) to the spectrometer via vacuum suitcase to prevent any contamination of the samples before XPS analysis.