XPS/AES Lab

In x-ray photoelectron spectroscopy (XPS), x-rays impinge on the sample and excite electrons from core and valence levels of the constituent atoms. Photoelectrons at specific kinetic energies pass through an analyzer and are directed to an electron multiplier device and detector. Sweeping the input energy to the analyzer produces a spectrum of the number of ejected photoelectrons at a specified KE. The KE of the electron is related to its binding energy (BE) in an orbital by KE = hv - BE - WF where hv is the known energy of the incident x-ray radiation and WF is the calibrated work function of the analyzer.  Oxidation states of each element in a sample can be determined with XPS. The position of a peak in a spectrum depends on the type and number of neighbors bonding to the atom. For example, the Fe peak appears in slightly different BE positions for Fe, Fe2O3, and FeO2. Analysis of an XPS spectrum to distinguish oxidation states of elements is usually done with the analyzer at high energy resolutions.  Our Lab is presently equipped with a Kratos XSAM 800 Surface Analysis System.

Kratos XSAM-800 XPS/Auger spectrometer

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June 20, 1999