The Peer review has evaluated this group as Excellent
The activity of the group comes from a 30 years tradition of spectroscopy work with synchrotron radiation, with conventional light sources and with electron beams. This evolution generated research activities in nearby field with cross fertilization between them. In the period considered in the present document (2003-2006) the main scientific goals refer both to material science using instruments developed in the past and to the improvement and/or construction of new instruments having advanced performances. The main focus has been on the following topics. - The study of electronic states of strongly correlated systems (an example are the high Tc superconductors). This has been done mainly with bulk sensitive techniques as X-ray Absorption Spectroscopy (XAS), Resonant Inelastic X-ray Scattering (RIXS) and high energy photoemission (XPS). The bulk sensitivity is needed since most of the information accumulated in the past has been obtained with surface sensitive techniques where the correlation properties are different from the bulk. The whole activity is based on synchrotron radiation and most of the activity has been done at the European Synchrotron Radiation Facility (ESRF) in Grenoble. - The study of magnetic systems at the scale of the electronic states (with XAS, RIXS and photoemission including spin resolved photoemission). Most of the work take advantage of the selectivity of x-ray spectroscopies giving measurements which are site and chemically sensitive. Work done at the ESRF, Grenoble. - The study of magnetic systems at the macroscopic scale with particular attention to the statistical fluctuations. A new technique has been developed to observe the Barkhausen effect in thin films with a MOKE (Magneto Optical Kerr Effect) ellipsometer having high sensitivity and high speed. Recent focus on magnetic organic systems and on the connection between magnetic and voltage noise. - The development of very high resolution RIXS instrumentation with top level achievements at the ESRF (Advanced X-ray Emission Spectroscopy (AXES) project) and at the Swiss Light Source where the new top level SAXES (SuperAXES) spectrometer is ready to be operated. The resolving 59 power (E/DE) of SAXES is typically 10,000 that is the world best in the soft x-ray range, to the authors’ knowledge. - High pressure studies with Synchrotron Radiation (XAS and RIXS from samples in anvil cells) with particular attention to the effects on the valence of Rare Earths compounds. - The development of high energy photoemission at the ESRF both around 1 keV and above several keV. Besides strongly correlated systems the goals were bulk sensitive spin resolved photoemission, bulk sensitive angle resolved photoemission and variable energy photoemission. This last option was finalized to the study of buried interfaces. - The setting up of a system for femtosecond time-resolved photoemission in the pump/probe mode using Ti:sapphire lasers as light sources. The energy range in the UV allows a considerable sensitivity to surfaces. A time of flight spectrometer has been built and already fully tested. Also reflectivity and magneto optical Kerr effect in the femtosecond timewindow have been implemented. - The setting up of a new laboratory of Auger microscopy (excitation with an electron gun). The SAM (Scanning Auger Microscopy) laboratory is devoted to the compositional analysis of spatially non homogeneous samples on the sub-micron scale (100 nm) with extreme surface sensitivity (1÷2 nm). The ongoing research is focused both on applications (alloys for industrial applications, etherostructure analysis for microelectronics and optics) and materials science (valence state, diffusion, segregation and localization of ligands and impurities in alloys). A feasibility study is in progress for the application of the technique in the field of artistic heritage conservation.