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排序方式: 共有1002条查询结果,搜索用时 15 毫秒
1.
P. Seelig A. Dax S. Faber M. Gerlach G. Huber T. Kühl D. Marx P. Merz W. Quint F. Schmitt H. Winter M. Würtz 《Hyperfine Interactions》1998,114(1-4):135-139
The investigation of the 1s HFS provides a good possibility for testing QED effects in a combination of a strong electric
and magnetic field. Here, we report about the laserspectroscopic measurements of the ground state hyperfine splitting in 207Pb81+. To handle this M1-transition in the infrared optical regime with its long lifetime, we developed a new detection technique
using a bunched ion beam. For the observation of fluorescence light, a new mirror system is adapted to the emission characteristics
from an ion beam at relativistic velocities.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
T. Engel M. Würtz S. Borneis St. Becker I. Klaft A. Kohl T. Kühl F. Laeri D. Marx K. Meier R. Neumann F. Schmitt P. Seelig L. Völker 《Hyperfine Interactions》1997,108(1-3):251-258
Laser spectroscopy at storage rings often suffers from a limited resolution due to Doppler-broadened resonances. Broadening
is caused by the velocity spread of the ions stored in the beam. In the following, the present status of our work on laser
systems specialized on the specific needs of laser spectroscopy at storage rings is reported.
Two pulsed laser systems were developed. One is a dye laser whose spectral bandwidth can be switched by inserting different
Littrow-prisms into the resonator. An increase in bandwidth up to a factor of 45 was achieved. This laser was used for fast
qualitative scans and high resolution measurements. The other laser system is a Nd : YAG laser pumped optical parametric oscillator.
It is a tunable laser system covering the spectral range from 410 to 4000 nm. Furthermore, a continuous wave laser with a
frequency shifted feedback cavity is described. It shows broadband emission with an adjustable bandwidth of up to 4.5 GHz.
This laser can be advantageous for laser cooling of ion beams.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
3.
M. Köhl A. Öttl S. Ritter T. Donner T. Bourdel T. Esslinger 《Applied physics. B, Lasers and optics》2007,86(3):391-393
We report an experimental investigation of two-particle correlations between neutral atoms in a Hanbury Brown and Twiss experiment.
Both an atom laser beam and a pseudo-thermal atomic beam are extracted from a Bose–Einstein condensate and the atom flux is
measured with a single atom counter. We determine the conditional and the unconditional detection probabilities for the atoms
in the beam and find good agreement with the theoretical predictions.
PACS 03.75.Pp; 05.30.Jp; 07.77.Gx; 42.50.Pq 相似文献
4.
A. v. Braunmühl 《Mathematische Annalen》1882,20(4):557-586
Ohne ZusammenfassungMit einer lithogr. Tafel. 相似文献
5.
R. Klein R. Grieser L. Hoog G. Huber I. Klaft P. Merz T. Kühl S. Schröder M. Grieser D. Habs W. Petrich D. Schwalm 《Zeitschrift für Physik A Hadrons and Nuclei》1992,342(4):455-461
We have performed for the first time precision spectroscopy on a coasting fast7Li+ ion beam in a storage ring. The ion beam moving with 6.4% speed of light was first electron cooled and then merged with two counterpropagating laser beams acting on two different hyperfine transitions sharing a common upper level (λ-system). One laser was frequency locked to thea 3 127J2 hfs frequency component established as a secondary frequency standard at 514 nm. The second laser was tuned over theλ-resonance, which was recorded relative to127J2 hfs components. This experiment is sensitive to the time dilation in fast moving frames and will lead to new limits for the verification of special relatively. The present status of the experiment and perspectives in accuracy are discussed. 相似文献
6.
A. Westphalen K. Theis-Bröhl H. Zabel K. Rott H. Brückl 《Journal of magnetism and magnetic materials》2006
We report on a magneto-optical Kerr effect (MOKE) investigation of alternating wide and narrow Fe bars, forming a two-dimensional periodic array. The magnetization reversal was studied by regular longitudinal Vector-MOKE in specular geometry as well as in Bragg-MOKE geometry, using the diffraction spots from the grating for hysteresis measurements. With Vector-MOKE a two-step switching process for the wide and narrow Fe bars is observed, indicative for a narrow switching field distribution in this array. In addition, hysteresis loops were determined as a function of the diffraction order for the hard and easy axis direction. The loops at different orders of diffraction can qualitatively and quantitatively be described by Fourier transformations of micromagnetic simulations. 相似文献
7.
Th. Mühge Yu. V. Goryunov K. Theis-Bröhl K. Westerholt H. Zabel I. A. Garifullin 《Applied magnetic resonance》1998,14(4):567-582
Magnetic and superconducting properties of Fe/Nb epitaxial bilayers have been studied. Single crystal Fe/Nb (110) bilayers with a Nb thicknessd Nb in the range from 250 to 650 Å and with a Fe thicknessd Fe in the range from 7 to 27 Å were prepared using molecular beam epitaxy techniques. Magnetization measurements showed the existence of a magnetically “dead” Fe-interface layer with a thicknessd NM varying strongly with minor modifications of the growth conditions. For bilayers with a small magnetic layer thicknessd M and a smalld NM the FMR measurements revealed an anomalous decrease of the effective magnetization 4πM eff of the ferromagnetic Fe layer below the superconducting transition temperatureT c. The absolute change of 4πM eff belowT c depends strongly on the actual values ofd M andd NM: upon decreasing bothd M andd NM the effect increases considerably. As a possible mechanism for the anomalous temperature dependence of 4πM eff belowT c we discuss a spatial modulation of ferromagnetic order due to a modification of the RKKY inter-action in the superconducting state. 相似文献
8.
C. G. Degiacomi A. Holenstein F. K. Kneubühl D. Huguenin 《International Journal of Infrared and Millimeter Waves》1990,11(1):55-59
We have designed and built a balloon-borne far-infrared 60 cm telescope equipped with He-cooled filters and a composite silicon bolometer with an NEP of 1.3·10–14 W/Hz1/2 for imaging, radiometry and spectroscopy of the Cygnus region at wavelengths up to 330 m. A test flight took place at the CNES balloon station at Aire/Adour, F, on May 8, 1989. The balloon stayed 41/2 h at the observation height of 39 km. Tests and results are discussed. 相似文献
9.
Surface composition of spray-dried milk protein-stabilised emulsions in relation to pre-heat treatment of proteins 总被引:2,自引:0,他引:2
Millqvist-Fureby A Elofsson U Bergenståhl B 《Colloids and surfaces. B, Biointerfaces》2001,21(1-3):47-58
Several important technical properties of spray-dried food powders depend on particle-liquid interactions (e.g. wettability, dispersability) and particle-particle interactions (e.g. flowability). It can be assumed that the chemical composition of the surface layer of the particles to a large extent determine these properties. The present study has been aimed to investigate the relation between the surface composition of spray-dried milk protein-stabilised emulsions and pre-heat treatment of the proteins. Solutions of WPC were heat-treated at low (60-90 degrees C) and high (140 degrees C) temperature and the degree of denaturation was determined, prior to the preparation of emulsions with rapeseed oil. The surface composition of the dry powders were established by using ESCA (electron spectroscopy of chemical analysis). The emulsions were characterised by droplet size distribution before spray drying and after dissolution of the powders. Also free fat extractions and estimations of wettability (dissolution rates) were performed. The powder surface coverage of protein decreased with increasing degree of protein denaturation before the emulsification, whereas the emulsion droplet size increased both before spray drying and after reconstitution of powders. The free fat extraction as well as the dissolution rate, whereof the latter decreased with increasing surface fat coverage, correlated well with the fat coverage of the powder surface. 相似文献
10.
The 15N chemical shifts of metronidazole (1), secnidazole (2), nimorazole (3) and tinidazole (4), radiosensitizers based on the 5-nitroimidazole motif, are reported. A detailed computational study of 1 is presented, calling special attention to the performance of various theoretical methods in reproducing the 13C and 15N data observed in solution. The most sophisticated approach involves density functional-based Car-Parrinello molecular dynamics simulations (CPMD) of 1 in aqueous solution (BP86 level) and averaging chemical shifts over snapshots from the trajectory. In the NMR calculations for these snapshots (performed at the B3LYP level), a small number of discrete water molecules are retained, and the remaining bulk solution effects are included via a polarizable continuum model (PCM). A similarly good accord with experiment is obtained from much less involved, static geometry optimization and NMR computation of pristine 1 employing a PCM approach. Solvent effects on delta(15N), which are of the order of up to 20 ppm, are not due to changes in geometric parameters upon solvation, but arise from the direct response of the electronic wavefunction to the presence of the solvent, which can be represented by discrete molecules and/or the dielectric bulk. 相似文献