Electron Affinity Of Oxygen Research Articles

Paradigms and paradoxes: what are the 54 electron affinities of O2?

Only one electron affinity of oxygen, 43(1) kJ mol−1 is generally cited since the molecular orbital theory anion bond order [3/4] gives an electron affinity, 14 kJ mol−1. However, electron correlation rules predict 27 bonding and 27 antibonding spin orbital coupling states. The relative bond orders (RBOs), 12/13 to [1/4] and the 13 valence electrons of superoxide are used to calculate electron affinities 103 to −243 kJ mol−1 consistent with experimental and theoretical values. These are used to construct 54 ionic Morse potentials.

Computer Simulation of Noncrystalline P2O5 , an Ionic–Covalent Oxide

The semiclassical molecular dynamics simulation method proposed earlier for studying ionic–covalent oxide systems was applied to noncrystalline P2O5 . The expressions for the potentials of ionic–covalent bonds were found. The internal energy comprises the contributions from the ionization energy of phosphorus, electron affinity of oxygen, Coulombic interaction, repulsion between ionic shells, and covalent interaction. The ionic charges were computed by minimizing the potential energy at each simulation step. Taking into account mixed bonding improves agreement with the experimental data on the density, energy, and structure of condensed P2O5 . The bond ionicity in glassy P2O5is about 68%. The proposed potentials are shown to be suitable for computing a number of properties of isolated P4O10molecules.

Computer Simulation of Small Noncrystalline Silica Clusters

The semiclassical molecular dynamics simulation method proposed earlier for studying ionic–covalent oxide systems is applied to small noncrystalline silica clusters. The internal energy comprises the contributions from the ionization energy of silicon, electron affinity of oxygen, Coulombic interaction, repulsion between ionic shells, and covalent interaction. The ionic charges are computed by minimizing the potential energy at each simulation step. Taking into account the intermediate type of bonding improves agreement with experimental density and energy data. The computed excess surface energy of silica clusters is almost independent of cluster size and is in reasonable agreement with the experimentally determined surface tension of liquid silica. At a distance of several nanometers, the interaction between silica clusters is very weak.

Lattice relaxation and charge-transfer optical transitions due to self-trapped holes in nonstoichiometric LaMnO3 crystal

We use the Mott-Littleton approach to evaluate polarisation energies in LaMnO$_3$ lattice associated with holes localized on both Mn$^{3+}$ cation and O$^{2-}$ anion. The full (electronic and ionic) lattice relaxation energy for a hole localized at the O-site is estimated as 2.4 eV which is appreciably greater than that of 0.8 eV for a hole localized at the Mn-site, indicating on the strong electron-phonon interaction in the former case. Using a Born-Haber cycle we examine thermal and optical energies of the hole formation associated with electron ionization from Mn$^{3+}$, O$^{2-}$ and La$^{3+}$ ions in LaMnO$_3$ lattice. For these calculations we derive a phenomenological value for the second electron affinity of oxygen in LaMnO$_3$ lattice by matching the optical energies of La$^{4+}$ and O$^-$ hole formation with maxima of binding energies in the experimental photoemission spectra. The calculated thermal energies predict that the electronic hole is marginally more stable in the Mn$^{4+}$ state in LaMnO$_3$ host lattice, but the energy of a hole in the O$^-$ state is only higher by a small amount, 0.75 eV, rather suggesting that both possibilities should be treated seriously. We examine the energies of a number of fundamental optical transitions, as well as those involving self-trapped holes of Mn$^{4+}$ and O$^-$ in LaMnO$_3$ lattice. The reasonable agreement with experiment of our predicted energies, linewidths and oscillator strengths leads us to plausible assignments of the optical bands observed. We deduce that the optical band near 5 eV is associated with O(2p) - Mn(3d) transition of charge-transfer character, whereas the band near 2.3 eV is rather associated with the presence of Mn$^{4+}$ and/or O$^-$ self-trapped holes in non-stoichiometric LaMnO$_3$ compound.

Oxygen Ordering in YBCO

It is shown that the ordering of oxygen found in the basal plane of YBa 2 Cu 3 O 6.5 can be explained in terms of the long-range Coulomb interaction between the oxygen ions, the ionization potential of copper and the electron affinity of oxygen. Furthermore, it is shown that the ordering induces self-doping and creates holes in the CuO 2 planes even though the nominal hole content of this substance is zero.

Spectroscopy of Molecular Ions in Noble Gas Matrices

Molecular ions are of considerable chemical and physical interest for comparing the spectroscopic and bonding properties of neutral mole­ cules with their positive and negative molecular ions. The study of molecular ions in the gas phase by photoelectron, photoionization mass, and ion cyclotron resonance spectroscopies can be complemented by infrared and optical absorption spectra of the molecular ion trapped in a solid inert gas host. Further ion studies with tunable infrared lasers will be greatly aided by the vibrational data obtained for molecular ions in noble gas solids. The ion-matrix interaction is of fundamental and practical interest as matrix. spectra of ions are related to the gas phase. Charged species in matrices form two general classes described in the literature as and chemically with respect to the counterion. The first ionic species characterized in matrices, Li + 0;, is of the latter type where the lithium cation and the superoxide anion are Coulombically bound together (1, 2), and charge transfer occurs be­ cause this electrostatic attraction more than makes up for the difference between the ionization energy of lithium and the electron affinity of oxygen. The next molecular ions identified in matrices, B2H; and �-, are of the isolated type where the cation is separated by an unde­ termined number of matrix atoms from the anion (3, 4). These ionic systems have been characterized as Coulomb ion pairs, which exist because of essentially zero overlap between the wavefunctions for the electron on the recipient molecule and the cation that provided the electron (5). Clearly, the formation of ions of the isolated type requires

Electron affinity of oxygen: F A Elder et al, J Chem Phys, 43(2), July 1965, 758–759

Electron affinity of oxygen: F A Elder et al, J Chem Phys, 43(2), July 1965, 758–759

Electron Impact Study of CO Using a Lozier Apparatus

A Lozier apparatus, modified in that a quasi-monoenergetic electron beam is used, has been employed to study CO. Ionization efficiency curves for both positive and negative ions were collected. From a detailed treatment of these data we deduced the ions produced, the appearance potentials for ions formed with zero kinetic energy, the processes in which they were produced, and the states of excitation of the fragments formed. From an analysis of our results alone, the dissociation energy of CO and the electron affinity of oxygen were determined, and they agreed within experimental error with the spectroscopic value of D(CO) of 11.11 ev and electron photodetachment value for EA(O) of 1.465 ev. Using the accepted values for D(CO) and EA(O), the electron affinity of carbon was determined from two different sets of our data to be between 1.34 and 1.74 ev. The lower value is in better agreement with other experimental determinations and with most of the recent empirical calculations for the EA(C).

The Electron Affinity of Atomic Oxygen

BRANSCOMB has provided further results in support of a figure of about 1.465 eV. for the first electron affinity of atomic oxygen E(O → O−), and there is strong evidence for this value. However, the difference between this result and the value of Metlay and Kimball1, E(O → O−) = 2.33 eV., obtained from electron attachment at a hot filament, still has to be accounted for. In addition, various extrapolation methods2 give rather lower values than 1.465 eV. for the first electron affinity of oxygen. For example, the extrapolation procedure used by us yielded E(O → O−) = 1.044 eV., and it seems appropriate to make some comments on this procedure.

Estimation of Electron Affinities of Oxygen by Extrapolations of Ionization Potentials

Estimation of Electron Affinities of Oxygen by Extrapolations of Ionization Potentials

On the Electron Affinities of Atomic Fluorine, Oxygen and Lithium

The Ritz variational method in conjunction with an extrapolation procedure has been employed to calculate the electron affinities of atomic fluorine, oxygen and lithium, the values obtained being 3.05, 1.12 and 0.74 eV respectively. In the case of fluorine the accord with the value 3.57 eV found by using the Born-Haber cycle is reasonable. The electron affinity of oxygen obtained from collision experiments is 2.2±0.2 eV, which is considerably larger than the value calculated in this paper. No comparison data are available for lithium.

A Study of Kinetic Energies of Atomic Ions Formed by Electron Impact in Nitric Oxide and Hydrogen Chloride

A study was made of the kinetic energy of the atomic ions formed by electron impact in NO and HCl. Their energy distribution was measured as a function of the electron energies at impact, and their ionization potentials were determined. The most probable values of the heats of dissociation of the molecules and of the molecular ions were calculated. Negative ions possessing up to 2.5 volts kinetic energy were observed in NO, and the electron affinity of oxygen was calculated. Negative ions found in HCl had less than 0.5 volt energy. The following is a summary of the results and the probable processes: