排序方式: 共有52条查询结果,搜索用时 15 毫秒
21.
H.F. Beyer D. Attia D. Banas E.-O. Le Bigot F. Bosch J.-Cl. Dousse E. Frster A. Gumberidze S. Hagmann S. Heß J. Hoszowska P. Indelicato P. Jagodzinski Chr. Kozhuharov Th. Krings D. Liesen X. Ma B. Manil I. Mohos M. Pajek D. Proti R. Reuschl J. Rzadkiewicz A. Simionovici U. Spillmann Z. Stachura Th. Sthlker M. Trassinelli S. Trotsenko A. Warczak O. Wehrhan E. Ziegler 《Spectrochimica Acta Part B: Atomic Spectroscopy》2009,64(8):736
A twin crystal-spectrometer assembly, operated in the focusing compensated asymmetric Laue geometry has been developed for accurate spectroscopy of fast highly charged heavy ions in the hard-X-ray region. Coupled to the focusing crystal optics is a specially developed two-dimensional position-sensitive X-ray detector which is necessary for retaining spectral resolution also for fast moving sources. We summarize the crystal optics and demonstrate the usefulness of the instrument for spectroscopy of both stationary and fast moving X-ray sources. Results are reported from several tests employing a 169Yb gamma-ray source and the Lyman radiation of one-electron Pb81+ ions traveling at a velocity corresponding to β ≡ v/c ≈ 0.59. The features of the instrument presented may be useful in many applications where it appears difficult to make the leap from conventional X-ray energy measurements to wavelength-dispersive spectroscopy based on crystal optics. 相似文献
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P. H. Mokler Th. Stöhlker R. W. Dunford A. Gallus T. Kandler G. Menzel H. T. Prinz P. Rymuza Z. Stachura P. Swiat A. Warczak 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1995,35(2):77-80
By decelerating highly-charged, very heavy ions to low energies in the storage and cooler ring, ESR, a new brilliant source for projectile x-rays has been obtained. In a first precision spectroscopy experiment up to 2·107 stored bare U92+ ions have been decelerated down to 49 MeV/u before detecting the characteristic projectile x-rays associated with one-electron capture at the ESR gas target. The Lyman, Balmer and Paschen series are distinctly observed for hydrogenic U91+ ions. 相似文献
24.
T. Blümke W. Meierkord H. -U. Menzebach J. F. Pennings Z. Stachura W. Vollmer B. Cleff 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,21(2):131-135
The alignment of theM 3 subshell of gold following proton impact ionization was studied with projectile energies in the range from 160 keV up to 5MeV. The experiments were performed by measuring the polarization of emittedM X-rays be means of a 5 in. Johansson crystal spectrometer. A good agreement of the experimental data and the results of theoretical SCA calculations was found. 相似文献
25.
Application of 204mPb perturbed angular correlation of γ-rays spectroscopy in coordination chemistry
Vibenholt J Schau-Magnussen M Stachura M Bjerrum MJ Thulstrup PW Arcisauskaite V Hemmingsen L 《Inorganic chemistry》2012,51(4):1992-1994
(204m)Pb perturbed angular correlation of γ-rays (PAC) spectroscopy has been applied successfully for the first time to detect the nuclear quadrupole interaction in a lead(II) coordination compound in a molecular crystal [tetraphenylarsonium lead(II) isomaleonitriledithiolate ([AsPh(4)](4)[Pb(2)(i-mnt)(4)])]. The recorded parameters from a powder crystalline sample are ν(Q) = 0.178(1) GHz and η = 0.970(7). The electric field gradient (EFG) was determined at the PW91/QZ4P level including relativistic effects using the two-component zeroth-order regular approximation method for both the [Pb(i-mnt)(2)](2-) monomer and the [Pb(2)(i-mnt)(4)](4-) dimer. Only the EFG for the latter compares favorably with the experimental data, indicating that the picture of this complex as a prototypical hemidirected coordination geometry with a stereochemically active lone pair on lead(II) is inadequate. Advantages and limitations of (204m)Pb PAC spectroscopy as a novel technique to elucidate the electronic and molecular structures of lead-containing complexes and biomolecules are presented. 相似文献
26.
Konrad Hinsen Eric Pellegrini Sławomir Stachura Gerald R. Kneller 《Journal of computational chemistry》2012,33(25):2043-2048
We present a new version of the program package nMoldyn, which has been originally developed for a neutron‐scattering oriented analysis of molecular dynamics simulations of macromolecular systems (Kneller et al., Comput. Phys. Commun. 1995, 91, 191) and was later rewritten to include in‐depth time series analyses and a graphical user interface (Rog et al., J. Comput. Chem. 2003, 24, 657). The main improvement in this new version and the focus of this article are the parallelization of all the analysis algorithms for use on multicore desktop computers as well as distributed‐memory computing clusters. The parallelization is based on a task farming approach which maintains a simple program structure permitting easy modification and extension of the code to integrate new analysis methods. © 2012 Wiley Periodicals, Inc. 相似文献
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A. Müller T. Bartsch C. Brandau A. Hoffknecht H. Knopp S. Schippers O. Uwira J. Linkemann A.A. Saghiri M. Schmitt D. Schwalm A. Wolf F. Bosch B. Franzke C. Kozhuharov P.H. Mokler F. Nolden M. Steck T. Stöhlker T. Winkler H. Danared D.R. DeWitt H. Gao H. Lebius R. Schuch W. Spies W. Zong G.H. Dunn W.G. Graham J.A. Tanis J. Doerfert D. Savin Z. Stachura 《Hyperfine Interactions》1998,114(1-4):229-235
New recombination experiments with merged cold beams of electrons and atomic ions have been carried out at the storage ring
facilities TSR in Heidelberg, ESR in Darmstadt, and CRYRING in Stockholm. A brief overview is given on the recent activities
in which the Giessen group was engaged. Topics of this research were dielectronic recombination (DR) of astrophysically relevant
ions, recombination of highly charged ions with respect to cooling losses in storage rings, field effects on DR, search for
interference effects in photorecombination of ions, correlation effects in DR of low-Z ions, spectroscopy of high-Z ions by DR, and lifetimes of metastable states deduced from DR experiments.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
29.
S. F. Sagnowski Z. Sulek M. Stachura J. Ogar 《Zeitschrift für Physik B Condensed Matter》1982,46(2):123-129
Single crystals of sodium nitrate, sodium chlorate and sodium bromate were investigated by continuous wave and Fourier transform pulse techniques. The sodium shielding tensors for studied compounds were found from the shift of the central line of23Na triplet, which was measured as a function of the crystal orientation. The shielding appears isotropic in NaNO3 and anisotropic in chlorate and bromate salts; the anisotropies are 0±2, 12±1 and 17±1 ppm respectively. It is suggested that lattice forces lowering the local symmetry at the sodium site are responsible for the observed effects of shielding anisotropy. 相似文献
30.
Lars Hemmingsen Monika Stachura Peter Waaben Thulstrup Niels Johan Christensen Karl Johnston 《Hyperfine Interactions》2010,197(1-3):255-267
PAC spectroscopy was first applied in biochemistry more than 40 years ago in a study of serum albumin (Leipert et al., Nature 220:907–909, 1968). Over the following decades a number of such applications have appeared in the literature, demonstrating that PAC spectroscopy is a useful tool in the study of biomolecules. Selected prototypical examples with 111mCd, 111Ag, and 199mHg are presented in this work with a particular focus on the biological role of metal ions in catalysis, protein structure and function, protein–protein interaction in biochemical reaction paths, in vivo binding of mercury ions to barley, and the use of de novo designed proteins to systematically explore the interaction of proteins and metal ions. 相似文献