Nearly linear orbital molecules on a pyrochlore lattice.

The interplay of spin-orbit coupling with other relevant parameters gives rise to the rich phase competition in complex ruthenates featuring octahedrally coordinated Ru. While locally, spin-orbit coupling stabilizes a nonmagnetic = 0 state, intersite interactions resolve one of two distinct phases at low temperatures: an excitonic magnet stabilized by the magnetic exchange of upper-lying = 1 states or Ru molecular orbital dimers driven by direct orbital overlap. Pyrochlore ruthenates RuO ( = rare earth, Y) are candidate excitonic magnets with geometrical frustration.

Theoretical and Experimental Study of the Spectroscopy and Thermochemistry of UC.

A combination of high-level calculations and anion photoelectron detachment (PD) measurements is reported for the UC, UC, and UC molecules. To better compare the theoretical values with the experimental photoelectron spectrum (PES), a value of 1.493 eV for the adiabatic electron affinity (AEA) of UC was calculated at the Feller-Peterson-Dixon (FPD) level.

Electronic Properties of UN and UN from Photoelectron Spectroscopy and Correlated Molecular Orbital Theory.

The results of calculations of the properties of the anion UN including electron detachment are described, which further expand our knowledge of this diatomic molecule. High-level electronic structure calculations were conducted for the UN and UN diatomic molecules and compared to photoelectron spectroscopy measurements. The low-lying Ω states were obtained using multireference CASPT2 including spin-orbit effects up to ∼20,000 cm.

Experimental and Computational Description of the Interaction of H and H with U.

The results of ab initio correlated molecular orbital theory electronic structure calculations for low-lying electronic states are presented for UH and UH and compared to photoelectron spectroscopy measurements. The calculations were performed at the CCSD(T)/CBS and multireference CASPT2 including spin-orbit effects by the state interacting approach levels. The ground states of UH and UH are predicted to be Ι and Λ, respectively.

Metal-Metal Bonding in Actinide Dimers: U and U.

Understanding direct metal-metal bonding between actinide atoms has been an elusive goal in chemistry for years. We report for the first time the anion photoelectron spectrum of U. The threshold of the lowest electron binding energy (EBE) spectral band occurs at 1.

The electron affinity of the uranium atom.

The results of a combined experimental and computational study of the uranium atom are presented with the aim of determining its electron affinity. Experimentally, the electron affinity of uranium was measured via negative ion photoelectron spectroscopy of the uranium atomic anion, U. Computationally, the electron affinities of both thorium and uranium were calculated by conducting relativistic coupled-cluster and multi-reference configuration interaction calculations.

Study of the Reaction of Hydroxylamine with Iridium Atomic and Cluster Anions ( = 1-5).

Elucidating the multifaceted processes of molecular activation and subsequent reactions gives a fundamental view into the development of iridium catalysts as they apply to fuels and propellants, for example, for spacecraft thrusters. Hydroxylamine, a component of the well-known hydroxylammonium nitrate (HAN) ionic liquid, is a safer alternative and mimics the chemistry and performance standards of hydrazine. The activation of hydroxylamine by anionic iridium clusters, Ir ( = 1-5), depicts a part of the mechanism, where two hydrogen atoms are removed, likely as H, and Ir(NOH) clusters remain.

CO Activation and Hydrogenation by Palladium Hydride Cluster Anions.

Mass spectrometric analysis of the anionic products of interaction between palladium hydride anions, PdH, and carbon dioxide, CO, in a reaction cell shows an efficient generation of the PdHCO intermediate and isolated formate product. Multiple isomers of the PdHCO intermediates are identified by a synergy between negative ion photoelectron spectroscopy and quantum-chemical calculations. It is shown that a direct mechanism, in which the H atom in PdH directly activates and hydrogenates CO, leads to the formation of the formate product.

CO Hydrogenation to Formate and Formic Acid by Bimetallic Palladium-Copper Hydride Clusters.

Mass spectrometric analysis of the anionic products of interaction between bimetallic palladium-copper tetrahydride anions, PdCuH, and carbon dioxide, CO, in a reaction cell shows an efficient generation of the PdCuCOH intermediate and formate/formic acid complexes. Multiple structures of PdCuH and PdCuCOH are identified by a synergy between anion photoelectron spectroscopy and quantum chemical calculations. The higher energy PdCuH isomer is shown to drive the catalytic hydrogenation of CO, emphasizing the importance of accounting for higher energy isomers for cluster catalytic activity.

Superconductivity at 4.8 K and Violation of Pauli Limit in LaIRu Comprising Ru Honeycomb Layer.

We discovered superconductivity at 4.8 K in the hexagonal layered compound LaIRu comprising a triangular lattice of the La and a honeycomb lattice of the Ru atoms. First-principles calculations reveal a two-dimensional band structure made up of La 5 and Ru 4 electrons and formal oxidation states +1.

Membrane-based torque magnetometer: Enhanced sensitivity by optical readout of the membrane displacement.

The design and realization of a torque magnetometer is reported that reads the deflection of a membrane by optical interferometry. The compact instrument allows for low-temperature measurements of tiny crystals less than a microgram with a significant improvement in sensitivity, signal-to-noise ratio as well as data acquisition time compared with conventional magnetometry and offers an enormous potential for further improvements and future applications in different fields. Magnetic measurements on single-molecule magnets demonstrate the applicability of the membrane-based torque magnetometer.

Photoswitchable stable charge-distributed states in a new cobalt complex exhibiting photo-induced valence tautomerism.

We report the synthesis and magnetic and photomagnetic behaviour of a novel valence tautomeric cobalt complex, [Co(3,5-dbbq)2(μ-bpym)] (1) (3,5-dbbq = 3,5-di-tert-butyl-1,2-benzoquinone and μ-bpym = 2,2'-bipyrimidine). The synthesis is performed by reacting Co2(CO)8 and μ-bpym in the presence of the ligand 3,5-dbbq in a mixed solvent under inert atmosphere. The magnetic behavior clearly shows the presence of electron transfer from the catecholate ligand to the cobalt center, producing valence tautomers of [Co(II)(SQ)2] with a transition temperature (T1/2) of 215 K.

No hypofrontality, but absence of prefrontal lateralization comparing verbal and spatial working memory in schizophrenia.

Hypofrontality and decreased lateralization have been two major, albeit controversial, results from functional neuroimaging studies of schizophrenia. We used fMRI to study cortical activation during a verbal and spatial working memory (WM) task (2-back) in 15 inpatients acutely ill with schizophrenia and 15 matched control subjects. We hypothesized (i) hypofrontality in patients in both tasks and (ii) decreased lateralization of prefrontal activation in patients under the assumption that, in controls, left prefrontal cortex (PFC) is engaged preferentially in the verbal task (verbal domain dominance) and the right prefrontal cortex is engaged preferentially in the spatial task (spatial domain dominance).

[Phosphorus-31-MR spectroscopy imaging in preoperative embolization treatment of meningioma].

Purpose: 31P MR spectroscopic imaging (31P SI) was evaluated in a clinical study as a method for monitoring presurgical devascularization of meningiomas. The aim was to assess noninvasively metabolic alterations in tumor and in healthy brain tissue before and after embolization.

Methods: Localized 31P MR spectra of the brain were obtained by means of 2D-SI (voxel size: 36 cm3) using a 1,5-T whole-body MR tomograph.