ABOUT THE TECHNIQUE

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.).

FACILITY AT APE

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.

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Technical specifications

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

The map of techniques

at MM building at Q2 building at Elettra experimental hall at CNR-IOM cloud at Fermi-T-Rex laboratory Surface & Nano Science Lab, STM/STS PLD XPS & ambient pressure XAS ARPES & Spin ARPES MOKE & Masked deposition system XPS MBE Oxides SPRINT laboratory SEM XRD PVD data repository open data data analysis
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Scientists in charge