Analysis of Bonding between Conjugated Organic Molecules and Noble Metal Surfaces Using Orbital Overlap Populations

The electronic structure of metal-organic interfaces is of paramount importance for the properties of organic electronic and single-molecule devices. Here, we use so-called orbital overlap populations derived from slab-type band-structure calculations to analyze the covalent contribution to the bonding between an adsorbate layer and a metal. Using two prototypical molecules, the strong acceptor 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) on Ag(111) and the strong donor 1H,1'H-[4,4']bipyridinylidene (HV0) on Au(111), we present overlap populations as particularly versatile tools for describing the metal-organic interaction. Going beyond traditional approaches, in which overlap populations are represented in an atomic orbital basis, we also explore the use of a molecular orbital basis to gain significant additional insight. On the basis of the derived quantities, it is possible to identify the parts of the molecules responsible for the bonding and to analyze which of the molecular orbitals and metal bands most strongly contribute to the interaction and where on the energy scale they interact in bonding or antibonding fashion.     

Structural defects and magnetic properties in the ordered compound CoGa

The magnetic susceptibility of the β-phase CoGa has been correlated with the defect structure of this phase. If only vacancies on the Co-sublattice (i.e. T-atom sublattice) and Co-atoms on the Ga-sublattice (i.e. transition antistructure atoms or TAS-atoms) are considered, their concentrations can be evaluated by density measurements combined with lattice constant determination. The susceptibility consists of a Curie-Weiss term which can be explained by magnetic moments located at TAS-atoms. The effective local magnetic moment per TAS-atom is found to be (5.02±0.06)μ_B. This value is independent of alloy composition and of heat treatment and is valid in the whole composition range for alloys quenched from 900°C as well as for those annealed after quenching or cooled slowly from high temperatures. With annealing out of quenched-in TAS-atoms the susceptibility decreases as predicted by this model.     

Chemical and pharmacologic studies on the derivatives of benzo(de)quinoline (I). 8. Natural and synthetic isoquinoline derivatives

Synthesis and cardiovascular evaluation of ketones 10 , 11 and 12 and of their derivatives 14 to 35 are described.     

High performance analytical characterization of refractory metals

It is first shown what effects trace impurities generally exert on metal properties and why trace analysis is essential to modern applications of refractory metals in today's high technology. The effect of trace impurities in metals on complex systems like microelectronic components is also discussed.It is then shown, what principal analytical requirements are mandatory for trace characterization of refractory metals at levels of rising purity (4 N to 6 N). A survey of analytical methods for trace and ultratrace characterization of refractory metals is given including the following methods: flame and graphite furnace atomic absorption spectrometry, ICP and DCP-atomic emission spectrometry, X-ray fluorescence spectrometry, activation analysis, mass spectrometric methods, especially SIMS and GDMS.     

Manganoan rockbridgeite Fe4.32Mn0.62Zn0.06(PO4)3(OH)5: structure analysis and 57Fe Mössbauer spectroscopy

The structure of the basic iron phosphate rockbridgeite [iron manganese zinc tris­(phosphate) penta­hydroxide] was reinvestigated with special emphasis on the cation distribution deduced from new X‐ray and ⁵⁷Fe Mössbauer data. Rockbridgeite is orthorhombic, space group Cmcm, and shows three different Fe sites, one with symmetry, another with m symmetry and the third in a general position. One phosphate group has the P atom on a site with m symmetry, while the other has the P atom at a site with mm symmetry. Two Fe sites are fully occupied by ferric iron, while Mn³⁺ and Fe²⁺ are situated at a third, principally Fe, site. Structural data, bond‐valence sums and polyhedral distortion parameters suggest a new inter­pretation of the rockbridgeite ⁵⁷Fe Mössbauer spectrum.