Volume Sensitive photoemission from solids with synchrotron radiation

The aim of the VOLPE (VOLume PhotoEmission from solids) project is to measure the volume electronic properties of solids via the Photoemission (PE) techniquewith Synchrotron Radiation. Photoemission, one of the most powerful spectroscopictools to investigate electronic properties, is characterized by strong surfacesensitivity, an aspect fully exploited for studying the topmost atomic layers of asolid. However, the presence of the surface, i.e. the reduced dimensionality and thebroken symmetry that the surface represents, often prevents from obtaining meaningfulinformation about the solid as a whole. Important examples of this difficultycan be found in the analysis of strongly correlated systems, as high temperaturesuperconductors and heavy fermions systems. The VOLPE set-up was assembledat ESRF in January 2004 and installed in February 2004 on beamline ID16 forfirst experiments. The results are very promising, especially considering that theinstrument is in its commissioning phase (see figures). In particular, we were ableto demonstrate: a) bulk sensitivity at about 5 keV and 7 keV kinetic energy, measuring2p core level emission from Co buried under a capping layer 120 thick.b) An overall energy resolution (photons+analyser) of 100-120 meV, measured onFermi level of polycristalline Ag. c) Negligible surface contribution, as revealedfrom the intensity measured on d and s band of Ag, without any preparation ofthe sample (neither scraping or sputtering), in a 10-7 mbar vacuum.