Auger channel

F. 15 Velocity distribution of ceramic compound flow in auger channel, output direction and rotational direction... 

The characteristic feature of flow laminations is the directional orientation of the anisometric particles in the shearing speed gradient of the auger channel, the pressure head and the die. Figure 3 pictures the fracture surfaces of extruded clay-body columns after drying showing various flow laminations caused by different clay mineral content. 

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 ... 

Experimental results show no temperature dependence for CdSe QDs and a much weaker temperature dependence at low temperatures for PbSe. In PbSe quantum dots, at low temperatures the Auger channel is more efficient than the multiphonon channel, which gives weak temperature dependence. At higher temperatures, when the electron-phonon channel becomes more efficient, it will... 

In other articles in this section, a method of analysis is described called Secondary Ion Mass Spectrometry (SIMS), in which material is sputtered from a surface using an ion beam and the minor components that are ejected as positive or negative ions are analyzed by a mass spectrometer. Over the past few years, methods that post-ion-ize the major neutral components ejected from surfaces under ion-beam or laser bombardment have been introduced because of the improved quantitative aspects obtainable by analyzing the major ejected channel. These techniques include SALI, Sputter-Initiated Resonance Ionization Spectroscopy (SIRIS), and Sputtered Neutral Mass Spectrometry (SNMS) or electron-gas post-ionization. Post-ionization techniques for surface analysis have received widespread interest because of their increased sensitivity, compared to more traditional surface analysis techniques, such as X-Ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES), and their more reliable quantitation, compared to SIMS. 

The decay on a picosecond time-scale, the so-called fast band, is understood as a quasi-direct recombination process in the silicon crystallites or as an oxide-related effect [Tr2, Mgl]. This fast part of the luminescence requires an intense excitation to become sizable it then competes with non-radiative channels like Auger recombination. The observed time dependence of the slow band is explained by carrier recombination through localized states that are distributed in energy, and dimensionally disordered [Gr7]. 

Resonance photoemission measurements have been recently made for U metal , and show indeed a resonant enhancement of the satelUte at 2.3 eV only for the threshold energy (5 A i2. hv = 94 eV) (Fig. 15). In addition the main peak at Ep shows the expected off-resonance behaviour. Further support for such an interpretation of the satellite is given by the analysis of the photon excited Auger emission. This is shown to be composed of two different bands also separated by 2.3 eV and due to the two screening channels by 5 f or 6 d states ... 

Figure 6.1 Schematic representation of one of the channels of the Is-1 Ne+ Auger decay one of the valence electrons (2s) is filling the core vacancy while another one (2p) is ejected into continuum. The same final state results also from the 2p —> Is recombination and 2s ionization (not shown here). The former ( direct ) and the latter ( exchange ) contributions interfere due to electron indistinguishability.

Let us first consider a simple Auger process with only a single decay channel [Nc = 1, see Eq. (4)]. Although not characteristic of K-shell Auger, such processes take place upon (n - l)p ionization of alkaline earth atoms, for example, in (2p 1) Mg+, where the only nonradiative decay pathway involves the two 3s electrons (2p-1) Mg+ (3s-2) Mg2+ + e. Assume that... 

The above analysis suggests that the spectacular effect of the neighboring charge on the single-channel Mg 2p Auger decay has to do with the polarizable Mg 3s orbital that is involved both in the recombination and in the ionization parts of the two-electron transition. Let us consider now a more general situation, in which a polarizable orbital is involved only in the ejection of the Auger electron. An example of such a transition is readily provided by 2s-ionized Mg. Indeed, 2s ionization leads to the process in which... 

G. Howat, T. Aberg, O. Goscinski, Relaxation and final-state channel mixing in the Auger effect, J. Phys. B 11 (1978) 1575. 

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