Morava -theory of extraspecial -groups

We compute the Morava -theory of some extraspecial 2-groups and associated compact groups.

     

The approximate inverse in action III: 3D-Doppler tomography

Summary. The approximate inverse is a powerful tool for solving first kind operator equations in a stable way. Its abstract convergence and stability theory developed in our articles [SIAM J. Numer. Anal., 37, 1909-1929,2000] and [Math. Comp., 72, 1399-1415, 2003] is applied to the reconstruction problem of 3D-vector field tomography resulting in a reconstruction algorithm of filtered backprojection type. For an analytically computed reconstruction filter (reconstruction kernel) convergence with rates as well as the regularization property are established.Mathematics Subject Classification (1991): 65J10, 65R10The work was partially supported by a Feodor Lynen-Fellowship of the Alexander von Humboldt-Foundation.Correspondence to: A. Rieder     

ac Stark shift and dephasing of a superconducting qubit strongly coupled to a cavity field

We have performed spectroscopy of a superconducting charge qubit coupled nonresonantly to a single mode of an on-chip resonator. The strong coupling induces a large ac Stark shift in the energy levels of both the qubit and the resonator. The dispersive shift of the resonator frequency is used to nondestructively determine the qubit state. Photon shot noise in the measurement field induces qubit level fluctuations leading to dephasing which is characteristic for the measurement backaction. A crossover in line shape with measurement power is observed and theoretically explained. For weak measurement a long intrinsic dephasing time of T2>200 ns of the qubit is found.     

Differentialthermoanalytische Untersuchungen im Dreistoffsystem Lithium-Kupfer-Germanium

Differential Thermoanalytic Investigations in the Ternary System Lithium-Copper-Germanium The section Li? (Cu:Ge = 1:1) of the ternary system lithium-copper-germanium was investigated by differential thermal analysis and X-ray methods. On the described section there are two peritectic reactions and one eutectic. Besides the well known phase Li₂CuGe two so far unknown phases Li_2,5CuGe and Li_1,25CuGe was investigated by differential thermal analysis.     

Identifying variable points on a smooth curve

LetX be a compact Riemann surface,n ≥ 2 an integer andx = [x ₁, …,x _n ] an unorderedn-tuple of not necessarily distinct points onX. Byf _x :X →Y _x we denote the normalization which identifies thex ₁, …,x _n and maps them to the only and universal singularity of a complex curveY _x . Thenf _x depends holomorphically onx and is uniquely determined by this parameter. In this context we consider the fine moduli spaceQ _X of all complex-analytic quotients ofX and construct a morphismS ⁿ (X) →Q _X such that each and everyf _x corresponds to the image of the pointx on then-fold symmetric powerS ⁿ (X). For everyn ≥ 2 the mappingS ⁿ (X) →Q _X is a closed embedding; the points of its image have embedding dimensionn(n ? 1) inQ _X . HenceS ²(X) is a smooth connected component ofQ _X . On the other hand, a deformation argument yields thatS ⁿ (X) is part of the singular locus of the complex spaceQ _X provided thatn ≥ 3.     

A candidate for an ion pair in the vapor phase: Proton transfer in complexes R3N - HX

Large-scale ab initio calculations have been performed on the complexes NH₃·HCl, NH₃·HBr, CH₃NH₂·HCl and CH₃NH₂·HBr. Two-dimensional energy surfaces as a function of R_N---X and R_HX have been scanned in order to explore the possibility for the formation of stable vapor-phase ion-pair complexes. While the complexes NH₃·HCl, NH₃·HBr and CH₃NH₂·HCl are still of the neutral type, the ionic form CH₃NH₃⁺·Br⁺ is energetically slightly more favourable than the neutral-type complex. Further increase in base strength of the amine will result in stable ionic amine HX complexes in the vapor phase.     

The chain mechanism of ozone destruction by CFCl3 in the 214 nm photolysis of its mixtures with oxygen

The effect of CFCl₃ (0.025–0.200 mbar) addition on the formation of ozone in 214 nm photolysis of oxygen (800–2000 mbar) was investigated. Kinetic analysis of the drastic reduction in ozone formation in the presence of CFCl₃ shows that it proceeds by a chain mechanism with a chain length of 5.07 ± 0.21(2σ). This chain length is independent of CFCl₃ and O₂ pressures as well as incident light intensity and the mechanism of the chain reaction is governed by the Cl generating reactions of ClO radicals. A mechanism based only on the self reaction of these radicals: ClO + ClO → Cl₂ + O₂ (7), Cl + ClO₂ (8), and Cl + OClO (9), followed by fast decomposition of ClO₂ into Cl and O₂, predicts a chain length which is considerably lower than the observed value. Incorporation of the reaction CFCl₂O₂ + ClO → CFCl₂O + ClO₂ (11) in the mechanism satisfactorily accounts for the observed chain length. A lower limit of 3 × 10^?12 cm³ molecule^?1 s^?1 for k₁₁ is estimated.     

Phase diagrams of the ternary systems Mn, Fe, Co, Ni---Si---N

Phase equilibria in the ternary systems Mn, Fe, Co, and Ni---Si---N are investigated and isothermal sections at 900°C (Fe---Si---N, Ni---Si---N), at 1000°C (Mn---Si---N, Co---Si---N) and at 1150°C (Fe---Si---N) are presented. In the system Mn---Si---N, Si₃N₄ coexists with MnSiN₂, Mn₃Si, Mn₅Si₃, MnSi, and MnSi_2−x. In the systems Fe, Co, Ni---Si---N, Si₃N₄ coexists with all binary silicides but reacts rapidly with iron above 1120 ± 10°C, and cobalt and nickel above 1170 ± 10°C to form binary silicides and nitrogen gas.     

Ternäre Phasen im Dreistoffsystem Lithium-Gallium-Germanium

Ternary Phases in the System Lithium—Gallium—Germanium The crystal structure of the ternary compound LiGaGe was refined by Fourier synthesis. The space-group of the structure is Nr. 186 (P6₃mc–C), and the Ga and Ge atoms form a Wurtzite lattice, the octahedral sites of which are occupied by the Li atoms. The homogeneity range of the compound LiGaGe was investigated, several further ternary phases with a cubic-fc. lattice could be found in the Li? Ga? Ge system.