Ejected electron spectroscopy compounds

The effect of ionizing radiation on molecular or ionic solids is to eject electrons, which often subsequently react at sites in the material well removed from the residual electron-loss centre. These electron-loss and electron-gain centres, or breakdown products thereof, are paramagnetic and have been extensively studied by e.s.r. spectroscopy. Results for a wide range of organo metals both as pure compounds and as dilute solid solutions are used to illustrate this action. Aspects of the electronic structures of these centres are derived from the spectra and aspects of redox mechanisms are discussed. 

One of the finest techniques for determining ionization potentials is photo-electron spectroscopy in which a mono-energetic beam of radiation is used to ionize the compound under investigation and the energies of the ejected electrons are measured (Turner, 1968). 

In other photoelectrochemical studies, the oxidation of Cr(CO)3(arene) compounds in acetonitrile was examined using the channel electrode technique (Compton et ai, 1993b,e). A combination of in situ EPR, fluorescence spectroscopy and voltammetry showed that the arene and, in some cases, CO were ejected on photolysis and the final chromium compound was either Cr(CO)3(CH3CN)3 or Cr(CO)2(CH3CN)4, which subsequently underwent a one-electron oxidation at the electrode surface. 

In investigations of Ce and its compounds, the fundamental question to be addressed concerns the degree to which the 4f electron can be treated by one-electron theory. Indeed, the 4f electron appears to exist in a highly correlated, localized state in some cases and a more band-like state in others. A closely related second question concerns the nature of the other electronic states and how they mix with the 4f states. Photoelectron spectroscopy does not always provide a simple or direct answer to these questions (ejection of an electron from a system perturbs the system), but photoemission does provide a great deal of insight. 

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