X-ray Photoemission Spectroscopy (XPS) is the most famous and used technique for the investigation of the chemistry of the material. In this experiment a monochromatic radiation impinges on a sample and exctracts 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 is possible to derive the chemical composition (stoichiometry) of the material under study and many information about the chemical state of each elements (oxidation state, chemical bonds, etc.).
In the MBE cluster system one chamber is devoted to XPS analysis. The chamber is a standard UHV chamber equipped with one close cycle cryostat that allows the control of the sample temperature in a range between 25 and 300 K. To permit XPS measurement the chamber is also 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 permit the rotation of the polar angle thus permitting the change from the (almost) normal emission condition to the grazing emission (and therefore from the grazing incidence of x-rays to normal incidence). The figure display the experimental system which is also equipped with 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|
My 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.