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41.
We have performed spin-polarized scanning tunneling spectroscopy of dipolar antiferromagnetically coupled Fe nanowires with a height of two atomic layers and an average separation of 8 nm grown on stepped W(110). Domain walls within the nanowires exhibit a significantly reduced width when pinned at structural constrictions. The lateral spin reorientation in the direction perpendicular to the wires has been studied with subnanometer spatial resolution. It is found that the spin canting in the Fe nanowires monotonously increases towards the step edges. 相似文献
42.
Olga A. Efremova Yuri V. Mironov Hans-Jürgen Pietzsch Holger Stephan Christiane Perrin Vladimir E. Fedorov 《Journal of Cluster Science》2009,20(1):77-81
Abstract A new cubane-type cluster complex Re4Te4Cl4(C4H4N3)4 · 2DMF has been synthesized by reaction of Re4Te4Cl8(TeCl2)4 with 2-aminopyrazine C4H5N3 in DMF. The crystal structure of compound has been solved by X-ray single crystal diffraction method. Crystal data for Re4Te4Cl4(C4N3H4)4 · 2DMF: a = 22.8718(16) ?, b = 8.5936(7) ?, c = 20.5720(17) ?, β
o = 106.493(2), V = 3877.1(5) ?3, R
1 = 0.0466, R
w(F
2) = 0.1191. In the complex bidentate aminopyrazine ligands are coordinated in two different types, namely, two of four aminopyrazine
ligands bind to a single rhenium atom, and each of two other ligands is coordinated as bridge between two rhenium atoms.
Graphical Abstract A new cubane-type cluster complex Re4Te4Cl4(C4H4N3)4 · 2DMF with two coordination modes of bidentate aminopyrazine ligands has been synthesized and structurally characterized.
相似文献
43.
AW Hilkert CB Douthitt HJ Schlüter WA Brand 《Rapid communications in mass spectrometry : RCM》1999,13(13):1226-1230
Of all the elements, hydrogen has the largest naturally occurring variations in the ratio of its stable isotopes (D/H). It is for this reason that there has been a strong desire to add hydrogen to the list of elements amenable to isotope ratio monitoring gas chromatography/mass spectrometry (irm-GC/MS). In irm-GC/MS the sample is entrained in helium as the carrier gas, which is also ionized and separated in the isotope ratio mass spectrometer (IRMS). Because of the low abundance of deuterium in nature, precise and accurate on-line monitoring of D/H ratios with an IRMS requires that low energy helium ions be kept out of the m/z 3 collector, which requires the use of an energy filter. A clean mass 3 (HD(+.)) signal which is independent of a large helium load in the electron impact ion source is essential in order to reach the sensitivity required for D/H analysis of capillary GC peaks. A new IRMS system, the DELTA(plus)XL(trade mark), has been designed for high precision, high accuracy measurements of transient signals of hydrogen gas. It incorporates a retardation lens integrated into the m/z 3 Faraday cup collector. Following GC separation, the hydrogen bound in organic compounds must be quantitatively converted into H(2) gas prior to analysis in the IRMS. Quantitative conversion is achieved by high temperature conversion (TC) at temperatures >1400 degrees C. Measurements of D/H ratios of individual organic compounds in complicated natural mixtures can now be made to a precision of 2 per thousand (delta notation) or, better, with typical sample amounts of approximately 200 ng per compound. Initial applications have focused on compounds of interest to petroleum research (biomarkers and natural gas components), food and flavor control (vanillin and ethanol), and metabolic studies (fatty acids and steroids). Copyright 1999 John Wiley & Sons, Ltd. 相似文献
44.
45.
Elemental analysis by quadrupole mass spectrometry with direct current powered glow discharge ion source has been improved for flat Cu samples. The line ratio of analyte to Ar-related interferents can be enhanced for several orders of magnitude when ion source geometry, ion extraction system and operating parameters are optimised quasi-simultaneously. Such an extreme improvement may partially be explained by different ion energy distributions depending on their origin: matrix and analytes, working gas, residual gases. Probably it is due to a synergistic effect of several processes needing further investigation. 相似文献
46.
Franziska Emmerling Werner Kraus Bernhard Noll Steffi Noll Hans‐Jürgen Pietzsch 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(12):m579-m582
The molecular structures of the two mononuclear title complexes, namely (4‐methoxybenzenethiolato‐κS)oxido[2,2′‐(3‐phenylpropylimino)bis(ethanethiolato)‐κ3S,N,S′]technetium(V), [Tc(C14H21NS2)(C7H7OS)O], (I), and (4‐methoxybenzenethiolato‐κS)oxido[2,2′‐(propylimino)bis(ethanethiolato)‐κ3S,N,S′]technetium(V), [Tc(C7H15NS2)(C7H7OS)O], (II), exhibit the same coordination environment for the central Tc atoms. The atoms are five‐coordinated (TcNOS3) with a square‐pyramidal geometry comprising a tridentate 2,2′‐(3‐phenylpropylimino)bis(ethanethiolate) or 2,2′‐(propylimino)bis(ethanethiolate) ligand, a 4‐methoxybenzenethiolate ligand and an additional oxide O atom. Intermolecular C—H...O and C—H...S hydrogen bonds between the monomeric units result in two‐dimensional layers with a parallel arrangement. 相似文献
47.
48.
Phase diagrams including the metastable zone width for the L‐asparaginase II from Escherichia coli with both PEG6000 and ethanol as a precipitant agent were determined, respectively. A turbidity technique giving results of nucleation and solubility limits in hours rather than in days was introduced. For the first time such data necessary for designing and controlling of crystallization processes of L‐asparaginase II are presented. Since the catalytical activity is an important parameter for L‐asparaginase II as an enzyme, a new type of phase diagram plotting the enzymatic activity as a function of temperature was established as well. Additionally, the crystalline L‐asparaginase II crystals with different shapes that formed in PEG6000 and ethanol, respectively, were also investigated by X‐ray Powder Diffraction (XRPD). 相似文献
49.
Pietzsch A Sun YP Hennies F Rinkevicius Z Karlsson HO Schmitt T Strocov VN Andersson J Kennedy B Schlappa J Föhlisch A Rubensson JE Gel'mukhanov F 《Physical review letters》2011,106(15):153004
Resonant inelastic soft x-ray scattering (RIXS) spectra excited at the 1σ(g) → 3σ(u) resonance in gas-phase O2 show excitations due to the nuclear degrees of freedom with up to 35 well-resolved discrete vibronic states and a continuum due to the kinetic energy distribution of the separated atoms. The RIXS profile demonstrates spatial quantum beats caused by two interfering wave packets with different momenta as the atoms separate. Thomson scattering strongly affects both the spectral profile and the scattering anisotropy. 相似文献
50.
In machine drawn weldor safety glasses with a different protection grade and a total iron oxide content of 6.8–9.5% the lattice coordination of iron and the Fe2+/Fetot ratio were determined by Mössbauer spectroscopy. In combination with electron beam microanalysis and specific sample preparation, homogeneity disturbances were observed inside the defect glass as well as on its surface. 相似文献