Photoelectron spectroscopy energy spectrum

XPS X-ray photoelectron spectroscopy [131-137] Monoenergetic x-rays eject electrons from various atomic levels the electron energy spectrum is measured Surface composition, oxidation state... 

Photoelectron spectroscopy provides a direct measure of the filled density of states of a solid. The kinetic energy distribution of the electrons that are emitted via the photoelectric effect when a sample is exposed to a monocluomatic ultraviolet (UV) or x-ray beam yields a photoelectron spectrum. Photoelectron spectroscopy not only provides the atomic composition, but also infonnation conceming the chemical enviromnent of the atoms in the near-surface region. Thus, it is probably the most popular and usefiil surface analysis teclmique. There are a number of fonus of photoelectron spectroscopy in conuuon use. 

An important property of the surface behaviour of oxides which contain transition metal ions having a number of possible valencies can be revealed by X-ray induced photoelectron spectroscopy. The energy spectrum of tlrese electrons give a direct measure of the binding energies of the valence electrons on the metal ions, from which the charge state can be deduced (Gunarsekaran et al., 1994). 

Unlike the stable molecule N2O, the sulfur analogue N2S decomposes above 160 K. In the vapour phase N2S has been detected by high-resolution mass spectrometry. The IR spectrum is dominated by a very strong band at 2040 cm [v(NN)]. The first ionization potential has been determined by photoelectron spectroscopy to be 10.6 eV. " These data indicate that N2S resembles diazomethane, CH2N2, rather than N2O. It decomposes to give N2 and diatomic sulfur, S2, and, hence, elemental sulfur, rather than monoatomic sulfur. Ab initio molecular orbital calculations of bond lengths and bond energies for linear N2S indicate that the resonance structure N =N -S is dominant. 

Other techniques utilize various types of radiation for the investigation of polymer surfaces (Fig. 2). X-ray photoelectron spectroscopy (XPS) has been known in surface analysis for approximately 23 years and is widely applied for the analysis of the chemical composition of polymer surfaces. It is more commonly referred to as electron spectroscopy for chemical analysis (ESCA) [22]. It is a very widespread technique for surface analysis since a wide range of information can be obtained. The surface is exposed to monochromatic X-rays from e.g. a rotating anode generator or a synchrotron source and the energy spectrum of electrons emitted... 

Energy Levels for Hole Injection. For the hole conductor TPD (6), measurements are available from different groups that allow a direct comparison of different experimental setups. The ionization potential that corresponds to the HOMO level under the assumptions mentioned above was measured by photoelectron spectroscopy to be 5.34 eV [230]. Anderson et al. [231] identified the onset of the photoelectron spectrum with the ionization potential and the first peak with the HOMO energy, and reported separate values of 5.38 and 5.73 eV, respectively. The cyclovoltammetric data reveal a first oxidation wave at 0.34 V vs. Fc/Fc+ in acetonitrile [232], and 0.48 V vs. Ag/0.01 Ag+ in dichloro-methane [102], respectively. The oxidation proceeds by two successive one-electron oxidations, the second one being located at 0.47 V vs. Fc/Fc+. 

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