Electron affinity estimation

In closing this Section, comparative studies on binary oxide semiconductors are available62,65,353,383 including one study383 where the electron affinities of several metal oxides (used as anodes in photoelectrolysis cells) were calculated from the atomic electronegativity values of the constituent elements. These electron affinity estimates were correlated with the Vih values measured for the same oxides in aqueous media.383... 

Electron affinities may be estimated using a Born-Haber cycle. 

So, within the limitations of the single-detenninant, frozen-orbital model, the ionization potentials (IPs) and electron affinities (EAs) are given as the negative of the occupied and virtual spin-orbital energies, respectively. This statement is referred to as Koopmans theorem [47] it is used extensively in quantum chemical calculations as a means for estimating IPs and EAs and often yields results drat are qualitatively correct (i.e., 0.5 eV). 

The XeF+ cation forms Lewis acid—base adduct cations containing N—Xe—F linkages with nitrogen bases that are resistant to oxidation by the strongly oxidizing XeF+ cation having an estimated electron affinity of the XeF+ cation of 10.9 eV (12). The thermally unstable colorless salt,... 

Here q represents the coulomb energy of an electron occupying a definite p]h orbital in unsubstituted benzene its value has been estimated to be about —2.7 v. e. = —60 kcal./mole.5 /3 is a resonance integral between adjacent orbitals its value has been estimated to be about —0.85 v. e. = — 20 kcal./mole.6 Sk is a constant, the purpose of which is to allow for the different electron affinities of the different atoms. For Sk > 0, the... 

The electron affinity values for many of the elements shown in Figure 8-17 appear to lie on the x axis. Actually, these elements have positive electron affinities, meaning the resulting anion is less stable than the neutral atom. Moreover, the second electron affinity of every element is large and positive. Positive electron affinities cannot be measured directly. Instead, these values are estimated by other methods, as we show in Section 8-1. 

C08-0073. Repeat the calculation of Problem 8.37 for K and I, using 500 kJ/mol as the estimated second electron affinity of iodine and assuming no change in distance of closest approach. 

S. W., Melton, C. M. Estimation of electron affinity based on structure acfivity relafionships. Quant. Struct.-Activ. Rd. 1993, 12, 389-396. 

The gas-phase lifetime of N20- is 10-3 s in alkaline solutions, it is still >10-8 s. Under suitable conditions, N20- may react with solutes, including N20. The hydrated electron reacts very quickly with NO (see Table 6.6). The rate is about three times that of diffusion control, suggesting some faster process such as tunneling. NO has an electron affinity in the gas phase enhanced upon solvation. The free energy change of the reaction NO + eh (NO-)aq is estimated to be --50 Kcal/mole. Both N02- and N03- react with eh at a nearly diffusion-controlled rate. The intermediate product in the first reaction, N02-, generates NO and... 

In Chapter 1 we discussed the electron affinities of atoms and how they vary with position in the periodic table. It was also mentioned that no atom accepts two electrons with a release of energy. As a result, the only value available for the energy associated with adding a second electron to O- is one calculated by some means. One way in which the energy for this process can be estimated is by making use of a thermochemical cycle such as the one that follows, showing the steps that could lead to the formation of MgO. 

While the first electrochemical reduction potential provides an estimate for Ac (assuming it is a reversible process), the second and higher reduction potentials do not provide the spectrum of single electron affinity levels. Rather, they provide information about two-electron, three-electron, and higher electron reduction processes, and, therefore, depend on electron pairing energy. Thus, the utility of solution-phase reduction potentials for estimating solid-state affinity levels is... 

Depending on the electron affinity of the catalyst, one of these two routes predominates. The dependence of the hydroperoxide decomposition rate on [ROOH] is in agreement with the conception of preliminary equilibrium sorption of hydroperoxide on the catalyst surface (Me2PhCOOH, AgO, 16m2 L 343 K) [263]). The equilibrium constant was estimated to be K 1 mol L and effective rate constant of described ROOH decomposition is /cis = 70s I[263]. 

The proposed subsequent reaction fits the fragmentation patterns observed in mass spectrometry where, even at 20 eV, group 14 centered radicals form in increasing order Sibasic data of this kind can provide estimates of kinetic behavior of such reactions, where M—M bonds are cleaved by electrophiles and which depend on the ionization potentials of the former as well as the electron affinity of the latter. 

F (g) —> F(g) + e To accomplish this, we need to calculate Zerr for the species in the left hand column and plot the number of protons in the nucleus against Zeff. By extrapolation, we can estimate the first ionization energy for F (g). The electron affinity for F is equal to the first ionization energy of F multiplied by minus one (i.e., by reversing the ionization reaction, one can obtain the electron affinity). 

The electron affinity (EA) of fluorine can be estimated from the first two entries of Table 2.2 as follows ... 

The relative position of the electronic level eo to the Fermi level depends on the electrode potential. We perform estimates for the case where there is no drop in the outer potential between the adsorbate and the metal - usually this situation is not far from the pzc. In this case we obtain for an alkali ion eo — Ep — where is the work function of the metal, and I the ionization energy of the alkali atom. For a halide ion eo — Ep = electron affinity of the atom. 

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