Topic
Valence (chemistry)
About: Valence (chemistry) is a research topic. Over the lifetime, 24937 publications have been published within this topic receiving 645252 citations. The topic is also known as: valency.
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TL;DR: In this article, photoelectron spectroscopy investigations of in-situ prepared AgO were conducted and the double peak structure of the O$1s$ signal with a remarkable chemical shift was found.
Abstract: We present photoelectron spectroscopy investigations of in-situ prepared AgO. The sample was prepared by room temperature oxidation of Ag in an electron cyclotron resonance ${\mathrm{O}}_{2}$ plasma. In contrast to other measurements based on ex situ prepared AgO powder samples, our investigations show a distinct double peak structure of the O $1s$ signal with a remarkable chemical shift of 2.9 eV between the two O $1s$ components. These two components can not be motivated from a crystallographic point of view as the oxygen sites are all equivalent in the unit cell. We interpret this double peak structure as a characteristic feature of AgO and discuss it in terms of mixed valences.
123 citations
TL;DR: In this paper, the spin-orbit matrix elements evaluated for ab initio model potential wavefunctions are found to agree with all-electron results to within better than 3% and corresponding agreement for the spectroscopic constants of PtH is excellent.
123 citations
TL;DR: Using a combination of HAADF-STEM imaging and atomically resolved EELS in an aberration-corrected TEM it is demonstrated the possibility of 2D atom by atom valence mapping in the mixed valence compound.
Abstract: Using a combination of HAADF-STEM imaging and atomically resolved EELS in an aberration-corrected TEM we demonstrate the possibility of 2D atom by atom valence mapping in the mixed valence compound . The ELNES from and cation sites are similar to those of and references. Comparison with simulations shows that even though a local interpretation is valid here, intermixing of the inelastic signal plays a significant role. This type of experiments should be applicable to challenging topics in materials science, like the investigation of charge ordering or single atom column oxidation states in e.g. dislocations.
123 citations
Journal Article•
TL;DR: The results demonstrate the feasibility and unique potential of time-resolved soft X-ray absorption spectroscopy to study ultrafast reactions in the liquid phase by directly probing the valence orbitals of first-row metals as well as lighter elements during the course of photochemical transformations.
Abstract: Solution-phase photoinduced low-spin to high-spin conversion in the FeII polypyridyl complex [Fe(tren(py)3)]2+ (where tren(py)3 is tris(2-pyridylmethyliminoethyl)amine) has been studied via picosecond soft X-ray spectroscopy Following 1A1 --> 1MLCT (metal-to-ligand charge transfer) excitation at 560 nm, changes in the iron L2- and L3-edges were observed concomitant with formation of the transient high-spin 5T2 state Charge-transfer multiplet calculations coupled with data acquired on low-spin and high-spin model complexes revealed a reduction in ligand field splitting of 1 eV in the high-spin state relative to the singlet ground state A significant reduction in orbital overlap between the central Fe-3d and the ligand N-2p orbitals was directly observed, consistent with the expected ca 02 Angstrom increase in Fe-N bond length upon formation of the high-spin state The overall occupancy of the Fe-3d orbitals remains constant upon spin crossover, suggesting that the reduction in sigma-donation is compensated by significant attenuation of pi-back-bonding in the metal-ligand interactions These results demonstrate the feasibility and unique potential of time-resolved soft X-ray absorption spectroscopy to study ultrafast reactions in the liquid phase by directly probing the valence orbitals of first-row metals as well as lighter elements during the course of photochemical transformations
122 citations