High-precision electron affinity of oxygen

Abstract

Negative ions are important in many areas of science and technology, e.g., in interstellar chemistry, for accelerator-based radionuclide dating, and in anti-matter research. They are unique quantum systems where electron-correlation effects govern their properties. Atomic anions are loosely bound systems, which with very few exceptions lack optically allowed transitions. This limits prospects for high-resolution spectroscopy, and related negative-ion detection methods. Here, we present a method to measure negative ion binding energies with an order of magnitude higher precision than what has been possible before. By laser-manipulation of quantum-state populations, we are able to strongly reduce the background from photodetachment of excited states using a cryogenic electrostatic ion-beam storage ring where keV ion beams can circulate for up to hours. The method is applicable to negative ions in general and here we report an electron affinity of 1.461 112 972(87) eV for 16O.

The OpenMolcas Web: A Community-Driven Approach to Advancing Computational Chemistry

“…Thus, the description of anionic states is a hard test for the ANO-R basis set. The electron affinity (EA) of oxygen is well-known experimentally with a very high precision (1.461 112 972(87) eV). Theoretical studies, with close to exact methods, predict an EA of oxygen in the range of 1.26 to 1.29 eV .…”

Relating Bond Orders and Bond Energies to Ionization Energies and Electron Affinities: A Quantitative Approach

“…Since the added electron in O 2 – is an antibonding electron, the electron attachment energy is a larger negative value for an oxygen atom than for the oxygen molecule, so the right side of this equation is negative. Therefore, the bond energy of O 2 – is less than the bond energy of O 2 , based on documented values for oxygen: ,,,, B E false( O 2 − false) − B E false( O 2 false) = E A false( O false) − E A false( O 2 false) = − 141 k J m o l − true( prefix− 86 k J m o l true) = − 55 k J m o l The addition of the antibonding electron weakens the bond by 55 kJ/mol. This is consistent with the qualitative prediction based on the bond order being reduced from 2 to 3/2.…”

Transition metal oxide complexes as molecular catalysts for selective methane to methanol transformation: any prospects or time to retire?

“…When making MO À species from MO 0 the additional electron is practically always placed into the 4s M orbital and not on the more electronegative oxygen terminal. The electron affinity (EA) values for the first-row transition metal monoxides range experimentally between 1.22 (CrO) and 1.54 (CoO) eV, [77][78][79][80][81][82][83][84] which is fortuitously close to the 1.46 eV 85 EA of the oxygen atom. Finally, we refer to the destiny of the 4s M electrons upon ligation, which is not discussed in the chemistry textbooks.…”