Electrons photoemitted

Although the photon penetration depth is relatively large in solid materials (a few micrometres for kiloelectronvolt X - rays), the analyzed photoelectrons come from the superficial layers only. Electrons photoemitted from deeper layers suffer inelastic collisions in the material. The main free path of electrons whose kinetic energy ranges between 0 and 1500 eV is typically 0.3 to 3 nm. 

Electrons photoemitted from the valence and conduction bands of a surface are detected as a function of angle. This gives information on the dispersion of these bands (which is related to surface structure) and also gives structural information from the diffraction of the emitted electrons. 

The diffraction of electrons photoemitted from core levels gives structural information on the surface. 

Electrons photoemitted from atomic core levels are detected as a function of energy. The shifts of core-level energies give information on the chemical environment of the atoms (see ARXPS, ARXPD). 

X-ray photoemission XPS Electrons photoemitted from atomic core levels are detected as a Composition and... 

Electrons photoemitted from the valence and conduction bands are detected as a function of energy to measure the elec-... 

XPS X-ray photoemis- Electrons photoemitted from atomic core Composition, oxi-... 

V. Deyirmenjian, J. Sipe, Coherent control of the angular distribution of electrons photoemitted from metal surfaces, Phys. Rev. Lett. 82 (1999) 4942. 

Resonance photoemission (RESPES) is a powerful tool for extracting species specific spectral information in materials with localized orbitals. In the resonance process, two distinct quantum pathways exist for creation of a photoelection (i) the direct photoemission process in which a valence electron is directly emitted, and (ii) the Auger channel in which a photoemitted core electron occupies the partially filled valence orbital, followed by a Koster-JCronig Auger decay in which the core hole is occupied and the valence electron photoemitted. Quantum interference between these two channels near the resonance threshold leads to strong cross-section variations for the localized states, allowing their signal to be differentiated from the contributions of other atomic species. For the case of copper, the two processes are ... 

Let us onsider an electron photoemitted at depth z in a flat and smooth solid in a direction making the angle B with the normal to the surface of the solid. The probability Q that the photoelecdon leaves the solid in this direction without energy loss is given by... 

In XPS spectra recorded with non-monochromatized X-ray, each peak is accompanied by a series of satellites on the low binding energy side of the peak, corresponding to electrons photoemitted by X-ray lines other than the Xai,2 line. The Xa3,4 satellite shown in Fig. 14 is generated by the Xa3,4 line of the magnesium X-ray source, the energy of which is about lOeV lower than the Ka, i line and is due to relaxation of doubly ionized Mg atoms. The intensity of the A1 satellite is... 

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