Experimental determination of deposition induced cluster deformation

We describe an experimental method to measure the cluster deformation of metal clusters deposited on a substrate. It is based upon the sensitivity of the cluster plasmon resonance on the geometric shape of the clusters; it uses optical spectroscopy with polarized light in oblique incidence. The proposed method was applied to silver clusters (mean diameter 2R = 2nm) produced in a supersonic beam and deposited on a quartz glass substrate. Cluster deposition and optical measurements were performed in situ in vacuum. At an estimated particle velocity of 1.5 · 10³ ms ^-1, we evaluated an axial ratio of c/a = 0.86 for the deposition induced deformation. This result is compared to data from molecular dynamical simulations. By varying the substrate coverage, the critical cluster coverage for the onset of electromagnetic cluster-cluster coupling and coalescence was determined to amount to 0.1 cluster-monolayers.     

Die Bestimmung der Minerals?uren im Essig

Ohne Zusammenfassung     

Combined local current distribution measurements and high resolution neutron radiography of operating Direct Methanol Fuel Cells

The current and fluid distribution in Direct Methanol Fuel Cells (DMFCs) was investigated in situ by means of combined high resolution neutron radiography and locally resolved current distribution measurements. The used neutron radiography set-up allows high spatial resolutions down to 70 μm at the full test cell area. A local formation of water droplets in the cathode flow field channels could be observed. Strongly inhomogeneous current distributions during cathodic flooding processes result in a performance loss of up to 30% of the initial value. Single CO₂ bubbles can be observed at low current densities. The water and current distribution during bi-functional operation of a DMFC was measured for the first time.     

Die Bestimmung des The?ns in den Theesorten des Handels

Ohne Zusammenfassung     

Zur Untersuchung und Beurtheilung des Honigs

Ohne Zusammenfassung     

Validation interlaboratory trial for ISO 12010: Water quality—Determination of short-chain polychlorinated alkanes (SCCP) in water

A validation interlaboratory trial was carried out to prepare ISO 12010: Water quality??Determination of short-chain polychlorinated alkanes (SCCP) in water??Method using gas chromatography/mass spectrometry (GC-MS) and electron capture negative ionisation (ECNI). The task was to determine the sum of short-chain polychlorinated n-alkanes with carbon chain lengths of C₁₀?CC₁₃ and a chlorine content between 49% (g/100?g) and 67% (g/100?g) in water by GC-ECNI-MS. The quantification had to be performed by multiple linear regression as described in ISO/DIS 12010, the compulsory method. Samples distributed were real river samples, and waste water spiked with a target concentration of 0.4 and 0.6???g/L for the sum of SCCPs, i.e. a concentration around the environmental quality target level according to the European Water Framework Directive. The different types of water samples tested were surface water with <150?mg/L suspended matter, surface water with 0.5?g/L suspended matter, and filtered waste waster. The interlaboratory trial included the extraction of the water samples, a column chromatographic clean up, a concentration step, and integration of chromatographic unresolved complex mixtures as well as the calibration and quantification by multiple linear regression. The reproducibility standard deviation of the standard concentration was 11.9%. Reproducibility standard deviations of concentrations in the three different water samples between 27.8 and 34.2% were achieved by 10?C12 participating laboratories from six countries.     

Using a grating analyser for SEMSANS investigations in the very small angle range

Spin-echo modulation small-angle neutron scattering (SEMSANS) is based on the detection of spatial beam modulation, which is induced by triangular spin echo precession regions and subsequent spin analyses. In order to detect such signal and exploit it for small angle scattering investigations neutron detection with sub-millimeter spatial resolution is required. Here an approach is reported where instead of a position sensitive detector an absorption grating is used to analyze the beam modulation stepwise. The spin-echo length scan in this case is performed by varying the sample-to-detector distance. The real space correlation functions of reference sample structures in the range 10² nm, i.e. giving rise to small-angle scattering in the very small-angle range, are recorded and analyzed successfully.