Solvated electron binding energies

Burger and Fluck [Bu 74a] were the first to employ ESCA for the study of solvation. They solved the problem outlined above by preparing a rapidly frozen solid from the solution to be examined (in an analogous way as in the Mossbauer studies of solvation), and measured the electron binding energies in the orbitals of the corresponding atoms of the solute in this solid. 

In the ESCA investigations, 1.2-dichloroethane, which has a low relative permittivity ( =10.1), was used as the inert solvent. Solutions of antimony pentachloride in this were prepared, and the donor solvent was added in small amounts, so that one molecule of this should be bound at the sixth coordination site of the SbCls, but the relative permittivity of the system should not be increased appreciably. In this way it could be ensured that the SbCls did not dissociate even partially, and hence the change in the electron binding energies of the antimony on addition of the donor solvent could be attributed only to the coordination of this solvent (to the solvation of SbCls). 

Fig. 5.10. ESCA data on solvates of SbClj with various donor solvents, determined in rapidly frozen dichloroethane solution (the Sb 3 5/2 electron binding energies are referred to the Cl 2pi 2 3/2 electron binding energies of the solvent), as a function of the donicities of the solvents [Bu 74a]...

Figure 21-26. Electron binding to the Watson-Crick MAMT base pair solvated by formic acid at the Hoogsteen site (I). In consequence of intermolecular proton transfers the radicals MAH" (III) and MAH"+(IV) are formed and the unpaired electron becomes localized on 9-methyladenine. Both initial electron attachment and two following intermolecular proton transfers are thermodynamically favourable and the accompanying changes of B3LYP electronic energies are given below the arrows in kcal/mol (Figure 7 of ref. [67]. Reprinted with permission. Copyright 2007 American Chemical Society.)...

Prom the viewpoint of the energy balance, solvated (localized) electrons, e, and positrons, e+, might participate in Ps formation. Actually e already resides in a small void and its binding energy there is about 1 eV. However, consideration of the data in Fig. 5.5 shows that in some liquids, electron localization occurs over a longer time than needed for Ps formation e does not yet exist during the Ps formation process [30]. 

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