X-ray Photoelectron Spectroscopy (XPS) is the most used technique for the investigation of the chemical properties of the material. In this technique a monochromatic radiation impinges on the sample and extracts photoelectrons. These photoelectrons are then collected and their energy dispersion is recorded by an electron energy analyzer. This forms the so called electron dispersion curve (EDC) or photoemission spectrum. From the analysis of the photoemission spectrum it is possible to derive the chemical composition (stoichiometry) of the material under study and several information about the chemical state of each element, such as oxidation state, chemical bonds, etc.
MBE cluster system includes one chamber devoted to XPS analysis. The chamber is equipped with one close cycle cryostat that allows the control of the sample temperature in a range between 25 and 300 K. The chamber is equipped with a double anode (Mg,Al) x-ray source and with a electrostatic hemispherical analyzer (mean radius 200 mm). The X-ray source is non-monochromatized and forms with the photoelectron propagation direction an angle of 90 degrees. The manipulator allows the rotation of the polar angle, in order to change from the (almost) normal emission condition to grazing emission (and therefore from grazing incidence of the x-rays to normal incidence). The figure displays the experimental system, which is also equipped with a sputtering device.
|Analyzer type||electrostatic hemispherical (mean radius 200 mm)|
|Field of view||100X800 microns (verticalXhorizontal)|
|Angular acceptance||+/-8 degree in the scattering plane|
|Resolving power||Up to 3000|
|Detector type||2D delay line detector with 300x300 channels|
|X-ray source||Al, Mg K-alfa radiation|
|Excitation energies||1486.7 and 1253.7 eV|
|Sample temperature||25-300 K|
Piero Torelli is responsible of APE-HE endstation and MBE Cluster within CNR-IOM. He obtained his Ph.D. in physics from the University of Paris Sud (Paris XI) with a doctoral thesis on the magnetic properties of small systems. He worked as post-doc at the EU-STREP FOX Project at ESRF in Grenoble. His research activity is focused on the investigation of the magnetic properties of nanostructure and thin films. The class of material that I study comprises: metals, diluted magnetic semiconductors and oxides, multiferroics and new functional materials.
My research activity is mainly devoted to the study of the interplay between magnetic and electronic-structural properties in highly correlated systems on the Cluster Growth at APE beamline (buried interfaces, 2D electron gases, ferroelectric and magnetic oxides heterostructures). I do also local contact activity on APE-HE beamline.