X-ray Photoelectron Spectroscopy on Clusters: From Water Clusters to Metal & Metal-Oxide Nanoparticles

Abstract: In the present work, two experimental setups aimed at the production of (1) water clusters and (2) metal-oxide nanoparticles were assembled and commissioned. The experiments on the cluster/nanoparticle beams were set up and performed at the FlexPES beamline of the MAX-IV synchrotron facility. In these experiments, photoelectron spectroscopy technique was the tool, with Scienta R4000 electron spectrometer used for collecting spectra in water valence region and the low-kinetic energy region in the first part, and in silver valence and 3d region for the second part. The experiments on water clusters were motivated by the questions existing in the radiotherapy treatment of tumours by electrons produced as the result of body water ionization. Our experiments showed a monotonous growth of the secondary electron production with the kinetic energy of the primary photoelectrons. The experiments on silver-oxide nanoparticles were inspired by the role silver plays in catalytic oxidation processes. The results shed some light on the spectroscopic signatures of two possible oxidation states in silver about which a discussion has been running for decades.