IPES probes the empty density of states above the Fermi level of conduction/valence band in condensed matter. The energy of the impinging electron is varied while photons are detected at fixed energy; in this way the spectrum of the density of unoccupied states is obtained. IPES technique is complementary to Photoemission (PES) and combined PES-IPES data provide information on the surface electronic transport.
The equipment includes two ultra high vacuum (UHV) chambers and a transfer load lock. The preparation chamber has standard Surface Science tools, with a CMA for Auger Electron Spectroscopy (AES) and Low Energy Electron Diffraction (LEED) and is also used for the growth of the films of the organic molecules and metals. The connected second UHV chamber is devoted to the empty electronic states analysis by means of Inverse Photoemission, with Geiger Mueller detectors and a highly collimated electron gun, overall resolution<0.3 eV. This configuration allows an Angular Resolved IPS acquisition (KR-IPS), i.e. the mapping of unoccupied electronic states vs the wave-vector k// . The Load lock is a movable UHV chamber which can be connected with other apparatus, including beamlines at nearby ELETTRA facility, to complement the KR-IPS with Direct Photoemission (PES), Core level photoemission and NEXAFS.
XPS is a surface spectroscopic technique for quantitative measurements of the elemental composition or stoichiometry and the chemical state of the present elements, like their oxidation state and chemical bonds. XPS is highly surface sensitive, giving chemical and binding energy information from the a narrow region close to the surface.
AFM is a surface sensitive technique permitting to obtain a microscopic image of the topography of a material surface and certain properties (like friction force, magnetization properties…). Typical lateral image sizes are within a range of only a few Nanometers to several Micrometers, and height changes of less than a Nanometer.
STM allows imaging conductive surfaces at the atomic scale. It is possible to characterize the distribution of surface terraces and steps, as well as to determine the atomic arrangement of (ordered) surface (over)structures.
XAS is sensitive to the local bonding environment of the atom absorbing the X-rays, providing information on oxidation states, local orbital symmetry, molecular orientation and chemically selective density of states. It is widely used in molecular and condensed matter physics, material science, engineering, chemistry, earth science and biology.
The pump-probe spectroscopy infrastructure provides in-situ probes of the excited state of the matter, i.e. in the time/frequency domain at the fs-ps scales.
