Oxygen K-edge X-ray Absorption Spectra

Abstract

We review oxygen K-edge X-ray absorption spectra of both molecules and solids. We start with an overview of the main experimental aspects of oxygen K-edge X-ray absorption measurements including X-ray sources, monochromators, and detection schemes. Many recent oxygen K-edge studies combine X-ray absorption with time and spatially resolved measurements and/or operando conditions. The main theoretical and conceptual approximations for the simulation of oxygen K-edges are discussed in the Theory section. We subsequently discuss oxygen atoms and ions, binary molecules, water, and larger molecules containing oxygen, including biomolecular systems. The largest part of the review deals with the experimental results for solid oxides, starting from s-and p-electron oxides. Examples of theoretical simulations for these oxides are introduced in order to show how accurate a DFT description can be in the case of s and p electron overlap. We discuss the general analysis of the 3d transition metal oxides including discussions of the crystal field effect and the effects and trends in oxidation state and covalency. In addition to the general concepts, we give a systematic overview of the oxygen K-edges element by element, for the s-, p-, d-, and f-electron systems. CONTENTSNO CO Ions of Two Atom Oxides 4.4. Molecules with Three Atoms Renner Teller Effect O 3 NO 2 CO 2 4.5. Atomic Adsorption 4.6. Molecular Adsorption Linear Dichroism CO on Metal Surfaces 4.7. Analysis of Catalytic Reactions 5. Liquids and Solutions 5.1. Water 5.2. Bio-Organic Molecules Amino Acids, Polypeptides, and Proteins DNA Components 6. Solid Oxides of s-and p-Elements 6.1. Alkali Metal Oxides 6.2. Alkaline Earth Oxides 6.3. General Considerations of p-Element Oxides 6.4. Overview of p-Element Oxides 6.4.1. Boron Oxides

Impact of the Transition Metal Dopant in Zinc Oxide Lithium‐Ion Anodes on the Solid Electrolyte Interphase Formation

“…The features B 1 (at 533.4 eV) and B 2 (at around 540.0 and 544.0 eV) can be assigned to the CO 1s–π* transition and the CO and CO 1s–σ* transition in Li 2 CO 3 . [ 50,51 ] Furthermore, all spectra also show a shoulder of peak A at around 532.2 eV, which is related to ROCO 2 Li alkyl carbonates. [ 25 ] Note that the latter signal also overlaps with a peak of Li 2 O.…”

“…[ 25 ] Note that the latter signal also overlaps with a peak of Li 2 O. [ 51,52 ] For ZnO, the shoulder peak A is most intense upon lithiation, for example, at 0.4 V and, thus, after the conversion reaction (Figure 6e). This increase in intensity of feature A is ascribed to the formation of larger Li 2 O aggregates during the conversion reaction, since pure ZnO lacks the “confinement effect” by the transition metal nano‐network.…”

In Situ/Operando Electrocatalyst Characterization by X-ray Absorption Spectroscopy

“… 117 At the same time, information from the K-edges of light elements can provide important complementary insight about the structure of multielement catalysts, 114 or that of the electrolyte, 84 interactions between adsorbates and catalysts, 118 , 119 and structural motifs in carbon-based materials that are currently used as nonprecious metal catalysts for the CO 2 electroreduction and oxygen reduction reactions. 120 − 123 An excellent review on the measurements and interpretation of O K-edge XAS was recently published by Frati et al 83 …”

“… 573 An alternative interpretation was, however, proposed by Frati et al., who suggested that the observed changes in the O K-edge XANES can be rather attributed to the formation of Ir 5+ species in the presence of Ir vacancies. 83 …”

On the Relationship Between Hydrogen-Bonding Motifs and the 1b1 Splitting in the X-ray Emission Spectrum of Liquid Water

“…The TD-DFT calculations were split into three groups; a convolution of the theoretical data was performed for each group with one third of the data, using Lorentzian functions with a width of half maximum of 0.20 eV, which is in the range of observed values for the core-hole K-edge lifetime broadening of oxygen. 16,17 The theoretical spectra shown in our figures represent the average for the spectra of the three groups. The shadows around each curve represent the standard deviation of the three groups, which can be interpreted as an error measure.…”