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61.
A.A. Gapud A.P. Weber J.A. Alexander L. Pham A. Khan R.I. Leatherbury A.P. Reyes L.L. Lumata P.L. Kuhns E.J. Valente R.E. Sykora 《Journal of Physics and Chemistry of Solids》2014
The synthesis and some physical properties of a new quasi-one-dimensional tetracyanidoplatinate, Cs4[Pt(CN)4](CF3SO3)2 (CsCP(OTf)) are reported and described in comparison to the well-known K2[Pt(CN)4]Br0.30·3.2H2O (KCP). Single-crystal X-ray diffraction reveals Pt–Pt spacings to be greater than those of KCP by 5% longitudinal and 38% transverse, but much shorter than comparable spacings in other non-partially oxidized platinates. Anomalies are observed between temperatures 100 K and 200 K: (1) Longitudinal DC conductivity is two orders of magnitude higher and is non-monotonic with temperature, showing a minimum at around 170 K. (2) Nuclear magnetic resonance (NMR) longitudinal relaxation time T1 is at least three orders of magnitude higher than that of KCP, and is also non-monotonic with temperature, showing a sharp peak at around 120 K. Since X-ray diffraction reveals no structural transition at 120 K, these suggest a possible lattice freezing or stiffening at around 120 K. 相似文献
62.
A new type of high performance liquid chromatography (HPLC) stationary phase was prepared, and its chromatographic properties were evaluated. The sorbent was composed of metallacarborane covalently bound to silica. Because of the chemical structure of the immobilized metallacarborane, the synthesized stationary phase was able to interact with nonpolar analytes via hydrophobic interactions. The chromatographic behavior of several low-molecular-weight hydrocarbons on the sorbent under typical reversed-phase conditions was compared with octadecyl-, sulfo phenyl- and aminopropyl-modified silica stationary phases. Moreover, as a consequence of the synthetic protocol employed, the immobilization of the metallacarborane led to the development of a zwitterionic chemically bonded phase, which demonstrated excellent resistance to "phase collapse" in a 100% aqueous environment. Finally, preliminary experiments indicated that the new stationary phase has the potential for utilization in hydrophilic interaction chromatography (HILIC) mode for the separation of polar compounds. 相似文献
63.
64.
S. Sykora A. Hübsch K. W. Becker 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,51(2):181-187
We study the one-dimensional Holstein model of spinless fermions interacting
with dispersion-less phonons by using a recently developed projector-based
renormalization method (PRM). At half-filling the system shows a
metal-insulator transition to a Peierls distorted
state at a critical electron-phonon coupling where both phases
are described within the same theoretical framework.
The transition is accompanied by a phonon softening
at the Brillouin zone boundary and a gap in the electronic spectrum.
For different filling, the phonon softening appears away from the Brillouin
zone boundary and thus reflects a different type of broken symmetry state. 相似文献
65.
66.
Christos Apostolidis Bernd Schimmelpfennig Nicola Magnani Patric Lindqvist‐Reis Olaf Walter Richard Sykora Alfred Morgenstern Eric Colineau Roberto Caciuffo Reinhardt Klenze RichardG. Haire Jean Rebizant Frank Bruchertseifer Thomas Fanghnel 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2010,122(36):6487-6491
67.
A strong polymeric helical complex of Ag(I) with biotin, a water-soluble vitamin also called vitamin H or B7, has been described in the crystal phase, yet with missing spatial characteristic of its solution structure. In this work, the complexation of d-(+)-biotin with Ag+ in aqueous solution has been studied by means of circular dichroism spectroscopy and mass spectrometry with electrospray ionization in positive mode (MS-ESI+). For comparison, the spectra of the Nujol suspension of studied systems in the solid state were also measured. The results indicate that the Ag(I)–biotin complex has a helical arrangement of the biotin molecules in solution. Our results show that the binding process involves the thioether sulfur atom and ureido carbonyl oxygen atom, while the carboxylate side group is not coordinated with the silver. The MS-ESI experiments have revealed the composite structures of Ag+ with biotin of various constitutions, which represent the products of the polymeric helical Ag(I)–biotin complex. 相似文献
68.
Single crystals of Cf(IO(3))(3) (1) were synthesized by the hydrothermal reaction of CfCl(3) and H(5)IO(6), and the structure was determined with single-crystal X-ray diffraction. This structural determination of 1 represents the first for a trivalent californium compound containing oxygen coordination. This compound has been further characterized with the use of Raman spectroscopy and emission spectroscopy. Crystallographic data: Cf(IO(3))(3), monoclinic, space group P2(1)/n, a = 8.7994(10) A, b = 5.9388(7) A, c = 15.157(2) A, beta = 96.833(2) degrees , V = 786.43(16) A(3), Z = 4 (T = 295 K). 相似文献
69.
The latest achievements in fluorescent nuclear track detector (FNTD) technology are described. FNTDs are aluminum oxide crystals containing aggregate oxygen vacancy defects and doped with carbon and magnesium (Al2O3:C,Mg). Unlike most nuclear track detectors, Al2O3:C,Mg is sensitive to low linear energy transfer (LET) radiation including secondary electrons resulting from interactions of photons with the crystal. A new image processing method is investigated as a technique to discriminate and measure the doses of gamma and fast neutrons in mixed field conditions. Dose dependencies for both gamma and neutron irradiated FNTDs are shown. The new image processing method increased the dynamic range of detectable neutron doses from 4 orders of magnitude for track counting method to at least 6 orders of magnitude by combining track counting with the new image processing method. The new image processing method is combined with a detector configuration utilizing three converters: Teflon®, polyethylene, and lithium fluoride. 相似文献
70.
Ji?í Mosinger Kamil Lang Pavel Kubát Jan Sykora Martin Hof Luká? Plí?til Bed?ich Mosinger Jr. 《Journal of fluorescence》2009,19(4):705-713
Polymeric polyurethane nanofabrics doped by zinc tetraphenylporphyrin (ZnTPP) and/or zinc phthalocyanine (ZnPc) photosensitizers
were prepared by the electrospinning method and characterized by microscopic methods, steady-state and time-resolved fluorescence,
and absorption spectroscopy. Nanofabrics doped by both ZnTPP and ZnPc efficiently harvest visible light to generate triplet
states and singlet oxygen O2(1Δg) with a lifetime of about 15 μs in air atmosphere. The energy transfer between the excited singlet states of ZnTPP and ground
states of ZnPc is described in details. All nanofabrics have bactericidal surfaces and photooxidize inorganic and organic
substrates. ZnTPP and ZnPc in the polyurethane nanofabrics are less photostable than incorporated free-base tetraphenylporphyrin
(TPP). 相似文献