Synthesis and characterization of alkoxide-derived pt nanoparticles

Identification of the species formed during the in situ reduction of hexachloroplatinic acid by sodium ethoxide, forming a Pt sol, is made. The solution phase is shown to consist of suspended metallic Pt nanoparticles (1-3 nm in diameter), acetaldehyde, and a Pt(II) species, identified by NMR and X-ray adsorption near-edge spectroscopy (XANES) to be NaPtCl3(C2H4), a sodium analogue of Zeise's salt [KPtCl3(C2H4)]. The NaPtCl3(C2H4) product exhibits greater stability in both ethanol and air than the conventional Zeise's salt, providing a means of storing the useful Zeise's anion [PtCl3(C2H4)-]. Electrochemistry, X-ray diffraction (XRD), and transmission electron microscopy (TEM) analyses have shown that the precipitate phase formed during the synthesis is composed solely of Pt particles approximately 6 nm in diameter and NaCl. Thermal gravimetric analysis/differential scanning calorimetry (TGA/DSC) showed that the color of the precipitate is an accurate gauge of the ratio of Pt to NaCl, with the lightest to darkest precipitates containing from 1% to 40% nanoparticulate Pt by mass, respectively. A comprehensive characterization of both phases formed has allowed us to propose a mechanism for the conversion of hexachloroplatinic acid to Pt nanoparticles.     

Koopmans' theorem and virtual orbital energies in the general SCF theory

The equality of the ionization potential and the orbital energy of the electron being removed is investigated using a general SCF theory for open-shell configurations. The significance of virtual orbital energies is investigated in the same context.

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Zusammenfassung Die Gleichsetzung von Ionisierungsenergie und entsprechender Einelektronenenergie wird für Konfigurationen mit unabgeschlossenen Schalen mit Hilfe einer allgemeinen SCE-Theorie geprüft. In diesem Rahmen wird auch die Bedeutung von virtuellen Einelektronenenergien untersucht.

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Résumé L'équation entre le potentiel d'ionisation et l'énergie orbitale de l'électron correspondant est examinée à l'aide d'une théorie générale SCE pour les configurations à couches ouvertes. Au cadre de cette théorie, la signification des énergies d'orbitales inoccupées est étudiée.

     

Spontaneous Imbibition Dynamics of Liquids in Partially-Wet Nanoporous Media: Experiment and Theory

Transport in Porous Media - Nanoscale spontaneous imbibition is a common process in nanoporous soil and unconventional reservoirs. Due to the complexity of these natural nanoporous media, the...     

Periodic Orbits and Bifurcations of the Vibrational Modes of the Ozone Molecule at High Energies

Russian Physics Journal - The study of quantum states near the dissociation threshold is necessary both to understand the formation of molecules and to explore accurately chemical reactions....     

Hybrid opto-TV image-processing system

Quantum Radiophysics Division. Translated from preprint No. 23, 1991 of the Lebedev Physics Institute, Russian Academy of Sciences, Moscow, Russia.     

The thermal ionization phase during the plasma formation in TM-1-MH tokamak

The start-up phase of discharge in a TM-1-MH tokamak has been investigated. We present a simple model describing the time evolution of electron density in a time interval where the bulk of electron distribution function is already Maxwellian and thermal ionization of neutral gas dominates. Comparison of the computed results with experimental data proved the validity of this model and allowed us to determine the electron temperature during this period of the discharge. The role of the run-away electron production during the start-up phase is discussed.     

π-Electron structure of heterocyclic molecules containing sulfur

The π-electron structure of sulfur containing heterocyclic molecules is approached from the point of view of correlating the degree of sulfur participation with the ability to propose resonance structures involving the whole of the hydrocarbon part of a molecule. If this is possible, there is a relatively low degree of sulfur participation. Any bond rigidity introduced into proposed resonance structures to avoid charge isolation or multiple C-S bonding correlates with a higher degree of sulfur participation. The results were obtained within the method originally proposed by Dewar and Harget with a new parameterization for sulfur as reported herein.