Charge transfer at F<Subscript>16</Subscript>CoPc and CoPc interfaces to Au

We analyze the electronic properties of the interfaces between cobalt phthalocyanine (CoPc), as well as fluorinated cobalt phthalocyanine (F₁₆CoPc), and an Au(100) single-crystal using X-ray photoemission spectroscopy and valence band ultraviolet photoemission spectroscopy. Our data demonstrate that for the monolayers of both materials a charge transfer occurs from the substrate to the center of the organic molecules resulting in a central Co(I) ion. This leads to the conclusion that this effect essentially is fluorination- and ligand-independent.     

On a least-squares formulation for hyperelastic,transversely isotropic problems

In the present work a mixed finite element based on a least-squares formulation is proposed. In detail, the provided constitutive relation is based on a hyperelastic free energy including terms describing a transversely isotropic material behavior. Basis for the element formulation is a weak form resulting from a least-squares method, see e.g. [1]. The L₂-norm minimization of the residuals of the given first-order system of differential equations leads to a functional depending on displacements and stresses. The interpolation of the unknowns is executed using different approximation spaces for the stresses (W^q (div, Ω)) and the displacements (W^1,p(Ω)), under consideration of suitable p and q. For the approximation of the stresses vector-valued shape functions of Raviart-Thomas type, related to the edges of the respective triangular element, are applied. Standard interpolation polynomials are used for the continuous approximation of the displacements. The performance of the proposed formulation will be investigated considering a numerical example. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Phosphatidylcholine dimers can be easily misinterpreted as cardiolipins in complex lipid mixtures: a matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometric study of lipids from hepatocytes

The liver is an important organ that is particularly involved in the lipid metabolism of the organism. Thus, high interest is nowadays focused on the lipid composition of the liver and particularly the liver parenchymal cells, the hepatocytes. Hepatocytes contain common phospholipids (PL) such as phosphatidylcholines, ‐ethanolamines and ‐inositols, for instance, that can be easily analyzed by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS) even without previous separation of the PL mixture. However, in addition to common PL, hepatocytes possess also significant amounts of cardiolipin (CLP). The MS analysis of this PL is quite challenging because it (a) has a higher mass than common lipids and (b) possesses a higher negative charge. We will show here that caution is required if CLP is analyzed directly from the total lipid extract because PC dimers may be interpreted as cardiolipins if the positive ion MALDI mass spectra are analyzed. Copyright © 2011 John Wiley & Sons, Ltd.     

Morphology, bond saturation and reconstruction of hexagonal SiC surfaces

Received: 21 March 1997     

SHG on ferromagnetic Gd films: indication of surface-state effects

The magnetization of 10-nm Gd films on W (110) has been investigated with second-harmonic generation (SHG). We observed a strong second-harmonic (SH) yield, which we attribute to resonance enhancement by the well-known Gd (0001) d-like surface state above the Fermi level. Since this state is spin-polarized it enhances the magnetic SHG contrast. The contrast, the relative phase between odd and even SH fields, and the amplitude ratio of these fields depend strongly on wavelength, which confirms the resonance enhancement. Further proof is provided by the fact that oxidation of the Gd surface reduces the SH yield by an order of magnitude. Received: 16 October 2001 / Revised version: 21 March 2002 / Published online: 11 June 2002     

Nanoscopic optical sensors based on functional supramolecular hybrid materials

This review highlights how the combination of supramolecular principles and nanoscopic solid structures enables the design of new hybrid sensing ensembles with improved sensitivity and/or selectivity and for the targeting of analytes for which selectivity is hard to achieve by conventional methods. Such ideas are bridging the gap between molecules, materials sciences and nanotechnology. Relevant examples will be detailed, taking into account functional aspects such as (1) enhanced coordination of functionalized solids, (2) enhanced signalling through preorganization, (3) signalling by assembly–disassembly of nanoscopic objects, (4) biomimetic probes utilizing discrimination by polarity and size and (5) distinct switching and gating protocols. These strategies are opening new prospects for sensor research and signalling paradigms at the frontier between nanotechnology, smart materials and supramolecular chemistry.     

Evidence for an aryl migration during the electron impact induced fragmentation of substituted aryloxymethylquinoxalines.

The electron impact (EI) mass spectra of 34 differently substituted 2-phenoxymethyl-, 2-naphthyloxymethyl-, 2-pyridinyloxymethyl- and 2-chinolinyloxymethylquinoxalines were recorded. The fragmentation patterns were examined by metastable ion analysis and exact mass measurements, employing finally also selective deuterium labelling. The inclusion of the substituted aryl ring moiety appears to be important for the fragmentation of the aryloxymethylquinoxalines. A molecular ion rearrangement is proposed for the observed loss of OH* and CHO* radicals. The influence of the different substituents on the aryl ring moiety on the rearrangement in the gas phase and on the resulting fragmentation was investigated.     

X-ray magneto-optics of lanthanide materials: principles and applications

Lanthanide metals are a particular class of magnetic materials in which the magnetic moments are carried mainly by the localized electrons of the 4f shell. They are frequently found in technically relevant systems, to achieve, e.g., high magnetic anisotropy. Magneto-optical methods in the X-ray range are well suited to study complex magnetic materials in an element-specific way. In this work, we report on recent progress on the quantitative determination of magneto-optical constants of several lanthanides in the soft X-ray region and we show some examples of applications of magneto-optics to hard-magnetic interfaces and exchange-coupled layered structures containing lanthanide elements. PACS 78.20.Ls; 78.70.Dm; 78.70.Ck; 78.20.Ci; 75.70.-i     

Intra-elemental photoelectron line intensities and their significance to quantitative analysis

Intraelemental relative photoelectron line intensities for 20 pure elements obtained under ultrahigh vacuum (5·10^?9 torr) and high resolution with cleaned surfaces are presented. Theoretical and experimental aspects of relative photoelectron line intensities as well as other characteristics of significance to quantitative analysis are discussed. Experimental data are related to theoretical results and compared with other recent work.