Disordered charge distributions and dielectric loss in extra dense flint glasses

The complex permittivities of some extra dense flint glasses (EDF glasses) have been studied. The dielectric features of the samples are dominated by their PbO content. Both refractive indices and dielectric losses exhibit a close relation to the concentration of Pb ions. The latter are located either at sites of the network atoms or filling the potential minima interstitially. They can be identified by their different relaxation mechanisms. The dispersion in the submillimeter wave and FIR area is characterized by a very broad distribution of comparably sharp resonant states. Thermal lens — or hysteresis effects can be excluded.     

Radiohochspannungsionophoretische Untersuchungen der Isotopenaustauschreaktionen zwischen Polythionaten,Thiosulfat und Sulfit

The isotopic exchange of³⁵S between thiosulfate/sulfite and tetrathionate/thiosulfate is examined. The kinetic data are determined. In both cases the reactions are of second order. As the isotopic exchange between tetrathionate/thiosulfate is very fast, these reaction components are used in high dilution. Furthermore, the extent of exchange during the separation is determined.      

Time-resolved vibrational spectroscopy

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Time-resolved vibrational spectroscopy     

Local versus hyperspherical modes of formaldehyde

Near-degenerate local versus hyperspherical modes of H₂CO are evaluated as vibrationally highly excited H₂C-stretches coupled to cold CO-bonds, for the electronic ground state (S ₀). Similar to isolated CH₂ fragments, the wavefunctions of local modes have frontier lobes pointing towards the two equivalent H·+·HCO radical product configurations. In contrast, the wavefunctions of hyperspherical modes extend approximately along arcs on spheres around the four-atom-coincidence. The wavefunctions are represented by reduced linear combinations of symmetry-adapted products of Morse times harmonic oscillator wavefunctions (LCSPM-HO). The dominant basis functions constituting the molecular vibrational states are selected by an efficient reduction technique.     

μSR investigation of single crystalline dysprosium

Muon spin rotation (μSR) data on a single crystalline sample of Dy have been obtained as function of temperature and applied hydrostatic pressure. The discontinuity observed in our new data at the phase transition at 85 K strongly suggests that the muons occupy tetrahedral interstitial sites, with a contact field B_C=-2.5 T at the lowest temperatures. Measurements with applied pressures up to 0.8 GPa show that the magnitude of the local fields increases with pressure at 0.3 GPa, and that the muon signal in the antiferromagnetic phase has essentially disappeared at 0.8 GPa. This revised version was published online in July 2006 with corrections to the Cover Date.     

Iterative regularization methods for atmospheric remote sensing

In this paper we present different inversion algorithms for nonlinear ill-posed problems arising in atmosphere remote sensing. The proposed methods are Landweber's method (LwM), the iteratively regularized Gauss-Newton method, and the conventional and regularizing Levenberg-Marquardt method. In addition, some accelerated LwMs and a technique for smoothing the Levenberg-Marquardt solution are proposed. The numerical performance of the methods is studied by means of simulations. Results are presented for an inverse problem in atmospheric remote sensing, i.e., temperature sounding with an airborne uplooking high-resolution far-infrared spectrometer.     

Sideband transitions and two-tone spectroscopy of a superconducting qubit strongly coupled to an on-chip cavity

Sideband transitions are spectroscopically probed in a system consisting of a Cooper pair box strongly but nonresonantly coupled to a superconducting transmission line resonator. When the Cooper pair box is operated at the optimal charge bias point, the symmetry of the Hamiltonian requires a two-photon process to access sidebands. The observed large dispersive ac-Stark shifts in the sideband transitions induced by the strong nonresonant drives agree well with our theoretical predictions. Sideband transitions are important in realizing qubit-photon and qubit-qubit entanglement in the circuit quantum electrodynamics architecture for quantum information processing.     

Pulse delay at diffractive structures under resonance conditions

An optical pulse incident upon a diffractive structure under resonance conditions may undergo a temporal delay. The effect is demonstrated with a pulse of Gaussian profile at two geometries: a waveguide grating and a single-mode waveguide. It is shown that the order of magnitude of the delay can be controlled by the parameters of the structures.     

Local magnetic field and muon site in CeAs

We report on zero field and longitudinal field μSR experiments on a CeAs single crystal between 3.3 and 12 K. Below the antiferromagnetic transition at 7.5 K a spontaneously precessing signal with a saturation frequency of \approx25 MHz representing the full sample amplitude has been found. From an analysis of the field dependence of the relaxation rate of this signal in \langle 100\rangle and \langle 110\rangle crystal orientation parallel to the muon spin and the applied longitudinal field, a \langle 100\rangle orientation of the local field at the muon site is concluded. This supports an AF‐I single‐\veck magnetic ordering. This revised version was published online in July 2006 with corrections to the Cover Date.     

Ultrafast ring-closure reaction of photochromic indolylfulgimides studied with UV-pump-IR-probe spectroscopy

The ring-opening and ring-closure reactions of a photochromic indolylfulgimide are investigated with femtosecond vibrational spectroscopy. Spectral signatures due to excited-state decay and vibrational cooling are seen in the mid-IR region. For the ring-opening reaction triggered with visible pulses, a lifetime of the excited electronic state of 4 ps was obtained in polar solution. In a nonpolar solvent, this time constant is reduced to 2 ps. The ring-closure reaction induced with UV pulses displays an excited-state lifetime and thus a building of the photoproduct of roughly 0.5 ps. For all processes, the subsequent cooling occurs on a 15-ps time scale lasting up to approximately 50 ps. The time-resolved IR measurements do not support the existence of any long-living intermediate states.