Zinn und Antimon in Legierungen

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Self-diffusion in Mg2SiO4 (forsterite) at high temperature

Summary The use of neutral primary particles for secondary ion mass spectrometry (NPB-SIMS) makes it possible to analyse the isotope concentration profiles of all constituent elements in Mg₂SiO₄ simultaneously. The results indicate

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Selbstdiffusion in Mg₂SiO₄ (Forsterit) bei hoher Temperatur: Modelluntersuchung für SIMS-Analysen an keramischen Oberflächen

     

A new optical method of measuring electron impact excitation cross section of atoms: Cross section of the metastable 6s6p P0 level of Hg

We report a new method that is potentially applicable to the measurement of electron impact excitation cross section of any atoms. Measurement of the cross section of the metastable 6s6p ³P₀ level of mercury is conducted to demonstrate the method, which involves using cavity ringdown spectroscopy to determine the absolute number density of mercury atoms in the 6s6p ³P₀ energy level. The measured cross section is 1.7×¹⁰−17 cm² and in agreement with the literature values. Compared with the optical methods that have been used during the last three decades, this new approach not only serves as an alternative optical method, but also is applicable to the atoms under both high and low pressure conditions.     

Liquid-helium cooled scanning far-infrared Fabry-Perot interferometer for astronomical observations with a balloon-borne telescope

We have developed a new liquid-helium cooled far-infrared Fabry-Perot interferometer (SFP) with high spectral resolution which will be incorporated and flown with our balloon-borne far-infrared 60 cm φ telescope FIT-FIT. This telescope has been built and already flown with other radiometric equipment in collaboration with the Geneva Observatory. The new spectrometer is designed to measure astronomical emission lines between 140 and 220 μm wavelength. Of special interest are the [NII]-line at 205 μm as well as the [CII]-line at 158 μm. In order to achieve high sensitivity we had to minimize the thermal radiation from the interferometer and its optics. For this reason all optics, including the scanning Fabry-Perot interferometer SFP, are liquid-helium cooled. This paper describes special new features of the design, operation, and test of its performance at liquid-helium temperature with optically pumped far-infrared gas lasers.     

Probehahme

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Zur Theorie der endlichen Gruppen topologischer Abbildungen von geschlossenen Flächen in sich

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Heterodiffusion of tin in N-type PbSe

Experimental results on the heterodiffusion coefficient of Sn in n-type PbSe between 550 and 750°C are presented. The conditions during diffusion resulted in a maximum deviation from stoichiometry, and diffusion profiles were obtained by SIMS.     

The weak energy condition and the expansion history of the Universe

We examine flat models containing a dark matter component and an arbitrary dark energy component, subject only to the constraint that the dark energy satisfies the weak energy condition. We determine the constraints that these conditions place on the evolution of the Hubble parameter with redshift, H(z)$H(z)$, and on the scaling of the coordinate distance with redshift, r(z)$r(z)$. Observational constraints on H(z)$H(z)$ are used to derive an upper bound on the current matter density. We demonstrate how the weak energy condition constrains fitting functions for r(z)$r(z)$.     

Micro-solid oxide fuel cells: status,challenges, and chances

Abstract  Micro-solid oxide fuel cells (micro-SOFC) are predicted to be of high energy density and are potential power sources for portable electronic devices. A micro-SOFC system consists of a fuel cell comprising a positive electrode-electrolyte-negative electrode (i.e. PEN) element, a gas-processing unit, and a thermal system where processing is based on micro-electro-mechanical-systems fabrication techniques. A possible system approach is presented. The critical properties of the thin film materials used in the PEN membrane are discussed, and the unsolved subtasks related to micro-SOFC membrane development are pointed out. Such a micro-SOFC system approach seems feasible and offers a promising alternative to state-of-the-art batteries in portable electronics. Graphical abstract  Graphical Abstract text