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Results for “electronic structures”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,549 records · Page 86
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Electronic structure and characterization of a uranyl di-15-crown-5 complex with an unprecedented sandwich structure

Understanding of the nature and extent of chemical bonding in uranyl coordination complexes is crucial for the design of new ligands for nuclear waste separation, uranium extraction from seawater, and other applications. We report in this paper the synthesis, infrared spectroscopic characterization, and quantum chemical studies of a molecular uranyl–di-15-crown-5 complex. The structure and bonding of this unique complex featuring a distinctive 6-fold coplanar coordination staggered sandwich structure and an unusual non-perpendicular orientation of the uranyl moiety are evaluated using density functional theory and chemical bonding analyses. Finally, the results provide fundamental understanding of the coordination interaction of uranyl with oxygen-donor ligands.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Yet again, new compounds found in systems with known binary phase diagrams. Synthesis, crystal and electronic structure of Nd 3 Bi 7 and Sm 3 Bi 7

The binary bismuthides Nd 3 Bi 7 and Sm 3 Bi 7 were synthesized and structurally characterized for the first time. Here, the results from the calorimetric analysis show that both compounds are stable only up to about 500 °C, which may explain why they were overlooked during the original assessment of the corresponding phase diagrams.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Probing solvation and reactivity in ionized polycyclic aromatic hydrocarbon–water clusters with photoionization mass spectrometry and electronic structure calculations

Polycyclic aromatic hydrocarbons (PAHs) may comprise up to 20% of the carbon budget in our galaxy and most PAHs condense onto water-rich icy grain mantles. Benzene–water clusters have been invoked as model systems for studying the photo-processing of water ice mantles containing PAHs. However, there is a paucity of information on larger aromatics, where the extended π cloud could affect photo-processing. Here in this study, tunable vacuum ultraviolet (VUV) photoionization of naphthalene–water clusters N x (H 2 O) y (N denotes naphthalene) is performed using synchrotron radiation and analyzed by reflectron time-of-flight mass spectrometry. Naphthalene clusters up to x = 4 are generated as are naphthalene–water clusters up to y = 25. At low photon energy (<11 eV), the naphthalene moiety is ionized and there is no proton transfer from N + to the water sub-cluster, which is very different from the benzene–water system. Protonated products, N[(H 2 O) x H] + and OH radical addition product (NOH)[(H 2 O) x H] + are generated above 11 eV, suggesting that water sub-clusters dominate the dynamics at high photon energies. Ab initio calculations are performed to decipher the experimental results. Energetics of the neutral structures N(H 2 O) 1–4 and their photoionized counterparts are calculated, including ionization on the N moiety as well as on the water sub-cluster. Energy decomposition analysis (EDA) is performed to understand trends in the binding between the naphthalene and the water sub-cluster in the ionized species.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Local electronic structure of the peptide bond probed by resonant inelastic soft X-ray scattering

The local valence orbital structure of solid glycine, diglycine, and triglycine is studied using soft X-ray emission spectroscopy (XES), resonant inelastic soft X-ray scattering (RIXS) maps, and spectra calculations based on density-functional theory. Using a building block approach, the contributions of the different functional groups of the peptides are separated. Cuts through the RIXS maps furthermore allow monitoring selective excitations of the amino and peptide functional units, leading to a modification of the currently established assignment of spectral contributions. The results thus paint a new-and-improved picture of the peptide bond, enhance the understanding of larger molecules with peptide bonds, and simplify the investigation of such molecules in aqueous environment.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Synthesis and Electronic Structure of Anionic 1,1'-diphosphametallocenes of Chromium and Iron

In this work, we report two anionic diphosphametallocenates, [K(2.2.2-crypt)][M(PC 4 Me 4 ) 2 ] (M = Cr, 2-Cr ; Fe, 2-Fe ). Both are low-spin ( S = ½) by EPR spectroscopy and SQUID magnetometry. This contrasts the high-spin ( S = ) ferrocenate, [K(2.2.2-crypt)][Fe(C 5 H 2 -1,2,4- t Bu) 2 ] ( 4-Fe ). Quantum chemical calculations suggest this is due to significant differences in ligand field splitting of the d-orbitals which also explain structural features in the 2-M complexes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗