Zur Existenz des Oxoniumions in festen basischen Aluminiumsulfaten

On the Existence of the Oxonium Ion in Solid Basic Aluminium Sulphates Oxonium alunite was investigated by ¹H-NMR-, heat capacity, electric conductivity, and thermoanalytic measurements. In the ¹H-NMR spectrum the existence of the oxonium ion was surely proved. From the results of the other investigations follow, that the oxonium ion is fast bonded in the structure and that exists an unimportant amount of mobile ionic charge carriers only.     

Reversible Coordination of Dioxygen by Tripodal Tetraamine Copper Complexes Incorporated in a Porous Silica Framework

The present study reports the synthesis and rational design of porous structured materials by using a templating method. A tetraethoxysilylated tripodal tetraamine (TREN) was covalently incorporated in a silica framework with a double imprint: A surfactant template and a metal ion imprint. The presence of a cationic surfactant (CTAB) endowed the material with a high porosity, and the tripodal or square‐pyramidal topology of the ligand was preserved thanks to the use of the silylated Cu^II complex. After removal of the surfactant and de‐metalation, the incorporated tetraamine was quantitatively complexed by CuCl₂ and the material has shown after thermal activation that a reversible binding of O₂ on the metal ions occurred. This chemisorption process was monitored by UV/Vis and EPR spectroscopies, and the Cu:O₂ adduct was postulated to be an end‐on μ‐η¹:η¹‐peroxodicopper(II) complex bridged by a chloride ion. The Cu^I‐active species, formed during the activation step, were fully recovered during several O₂ binding cycles. The high reactivity of the copper complexes and the room‐temperature stability of the dioxygen adduct were explained by the fine adaptability of the tripodal ligand to different geometries, the confinement of the active sites in the hybrid silica that protect them from degradation by a control of the metal‐ion microenvironment, as well as the short‐range lamellar order of the copper complexes in the framework.     

Hybrid states of Tamm plasmons and exciton-polaritons

We have demonstrated theoretically that it is possible to use the resonant coupling of exciton-polaritons in a planar microcavity and Tamm plasmons at a metal film on the surface of the structure to provide lateral spatial control of the exciton-polaritons within the cavity. The resonant coupling of the Tamm plasmons to cavity exciton-polaritons results in a triplet of hybrid plasmon–exciton-polariton modes with the lowest at a significantly lower energy than that of the unperturbed exciton-polaritons. Further, a patterned metal film on the structure surface can provide a sufficiently large lateral modulation of the excitation energy that localization of the exciton-polaritons within chosen regions of the cavity is possible. We show how the approach opens the way to a practical demonstration of polariton channels, traps, and devices, including logic gates.     

The effect of N2O on the isotopic composition of air-CO2 samples

The ionisation efficiencies of N2O vs. CO2 as well as their ratios were measured in detail introducing clean N2O and CO2 into the electron impact ion source of an isotope ratio mass spectrometer. Changes in the ionisation efficiency ratio (IER) were found for different electron energy settings and compared with the ratios of literature ionisation cross-section values for pure N2O and CO2. To establish the influence of mixtures of N2O and CO2 in a mass spectrometer, artificial air mixtures were prepared by mixing different amounts of N2O and CO2 from well-calibrated spike cylinders with CO2-free air. The mixing ratios varied from 8-512 ppb for N2O and from 328-744 ppm for CO2. With these mixtures the effects of varying N2O concentrations on apparent CO2 isotope ratios in air samples were determined. After applying a mass balance correction the delta13C results were consistent within small error margins. The data seemed almost independent from a particular choice for the IER of N2O vs. CO2 in the correction algorithm. For delta18O a small effect of the ionisation efficiency ratio of N2O vs. CO2 was found. Several sets of calculations were made varying the IER between 0.88 and 0.62. The dependence of delta18O was the smallest with an adopted IER of 0.68-0.72 in the mass balance correction equation for isotopic analysis of CO2 in air. For high-precision measurements of the CO2 stable isotope ratios in air samples a careful assessment of the mass spectrometer performance is necessary. Different ion sources, even different ion source settings, alter the IER of N2O vs. CO2 which is used in the N2O correction algorithm. Preferably, the specific mass spectrometric behaviour should be established with clean N2O/CO2 mixtures or with air mixtures covering a larger range of N2O concentrations.     

Submillimeter wave generation by second harmonic operation of tunable gyrotrons

The gyrotrons developed at the University of Sydney are tunable sources of millimetre and submillimetre radiation. The generation of submillimetre wavelengths requires operation at the second harmonic of the electron cyclotron frequency, or higher. Our latest gyrotron, GYROTRON IVA, has successfully achieved second harmonic operation and obtained frequencies up to 590 GHz (=0.51 mm). The experimental results and conditions for second harmonic operation will be presented. The design of a new gyrotron, GYROTRON V, which is especially optimised for the second harmonic, will also be included.     

Amplitude modulation of submillimeter wave gyrotron output

Amplitude modulation of gyrotron by a small modulation of the anode voltage is calculated using an energy transfer formula. Experimental measurements using a submillimeter wave gyrotron are in good agreement. One hundred percent modulation of the output at frequencies up to several hundred kilohertz has been achieved with anode modulation levels of only a few percent. Numerical calculations lend further support to the experimental results.