Hole-filling spectroscopy

Dian BC, Longarte A, Winter PR, Zwier TS (2004) The dynamics of conformational isomerization in flexible biomolecules. I. Hole-filling spectroscopy of N-acetyl tryptophan methyl amide and N-acetyl tryptophan amide. J Chem Phys 120 133... 

A popular electron-based teclmique is Auger electron spectroscopy (AES), which is described in section Bl.25.2.2. In AES, a 3-5 keV electron beam is used to knock out iimer-shell, or core, electrons from atoms in the near-surface region of the material. Core holes are unstable, and are soon filled by either fluorescence or Auger decay. In the Auger... 

AES Auger electron spectroscopy After the ejection of an electron by absorption of a photon, an atom stays behind as an unstable Ion, which relaxes by filling the hole with an electron from a higher shell. The energy released by this transition Is taken up by another electron, the Auger electron, which leaves the sample with an element-specific kinetic energy. Surface composition, depth profiles... 

The chemisorption bond between CO or NO and Pt is mainly attributed to the interaction of a electron of the adsorbate with the d hole of Pt, whereas the site selection of the adsorbate is assisted by the interaction between the adsorbate 2tt and the Pt 5d orbital. The shape of the d orbital is important for this site selection. The five d orbitals in the Oh space group are generally classified into eg (dx2 y2 and d3,2 r2) and r2g (dxy, dyz, and dM) orbitals with respect to the cubic coordinate. Of the two states of Pt, t2g has more d hole character [90], and furthermore, only the f2g state is upward-shifted and the eg is preferentially filled as a result of s-d hybridization [89]. The d band filling in the eg state due to the s-d hybridization for the alloy is supported by the band structure of this alloy in the Y-L direction observed by angle-resolved photoemission spectroscopy using synchrotron radiation [88]. 

Auger electron spectroscopy (AES) — When an electron is removed from a level of energy E of a surface atom, the hole is filled by an electron from a higher electronic level E2. The energy difference between the two involved orbitals is transferred to a third electron of level /i3 which then leaves the atom and may be measured as an Auger electron. Due to the mean free path of the electrons AES is a surface analytical method with a depth resolution of some few nm as in the case of XPS. The excitation of electrons and the primary ionization process... 

Another way to see that we are dealing with a hole conduction process is to consider the outermost electronic shell of the copper ions, which is called a 3d level in the notation of atomic spectroscopy. This level can hold a maximum of 10 electrons, and is filled for the ion Cu+. The ion Cu + has only nine electrons in its 3d level, which corresponds to 10 electrons plus one hole, and Cu + has 8 electrons, or 10 electrons plus two holes. Electrical current in the normal state is carried by these holes, which are in the conduction band, via the hopping mechanism of equation (21). Electric current in the superconducting state is carried by Cooper pairs formed from these holes. 

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