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21.
Chelsea N. Widener Alexandria N. Bone Mykhaylo Ozerov Rachael Richardson 路正光 Komalavalli Thirunavukkuarasu Dmitry Smirnov 陈学太 薛子陵 《无机化学学报》2020,36(6):1149-1156
最近Ruamps和同事发现三角双锥构型的Ni(Ⅱ)配合物[Ni(Me6tren)Cl]ClO4(1,Me6tren=tris(2-(dimethylamino)ethyl)amine)具有大的单轴磁各向异性(J.Am.Chem.Soc.,2013,135:3017-3026)。他们利用HF-EPR研究获得横向零场分裂(ZFS)参数E=1.56(5)cm-1但未能确定轴向零场分裂参数D。在本工作中,我们利用0~17.5 T和5 K的变磁场远红外光谱(FIRMS)来检测自旋基态S=1中的MS=±1和MS=0态之间的磁跃迁。在FIRMS中直接观察到Zeeman分裂态之间的跃迁,得出轴向ZFS参数D=-110.7(3)cm-1。我们对1的晶体结构进行了Hirshfeld表面分析,揭示了1分子中的阳离子与阴离子之间以及分子之间的相互作用。 相似文献
22.
The effect of nonradiative reverse energy transport (NRET) in two donor-acceptor systems was studied experimentally. It was found that the NRET occurring in system I; rhodamine 6G (donor) and rhodamine B (acceptor), considerably lowers the emission anisotropy at medium and high concentrations. These results qualitatively confirm the predictions of the approximate theoretical approach of L. Kulak and C. Bojarski (see the preceding paper). In system II; rhodamine 6G (donor) and Nile Blue (acceptor), for which the NRET process does not occur, a good agreement with no-back-transport theory was obtained. 相似文献
23.
A. A. Isaeva A. I. Baranov Th. Doert M. Ruck V. A. Kulbachinskii R. A. Lunin B. A. Popovkin 《Russian Chemical Bulletin》2007,56(9):1694-1700
New metal-rich mixed nickel-silicon and nickel-germanium chalcogenides, Ni5.68SiSe2, Ni5.46GeSe2, and Ni5.42GeTe2, were synthesized by high-temperature ceramic techniques. The X-ray diffraction study of single crystals grown from a molten
flux revealed that the compounds are isostructural and crystallize in the tetragonal system (space group I4/mmm, Z = 2). These compounds are the first members of the family of M7−δEX2-type (M = Ni or Pd; E = Sn or Sb; X is chalcogen) intergrowth structures containing “light” p elements E. Resistivity measurements on pressed textured pellets showed that both selenides are anisotropic metallic conductors
in the directions parallel and perpendicular to the heterometallic bond systems. The geometric criteria of stability of the
intergrowth structure type under consideration are discussed.
Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1632–1638, September, 2007. 相似文献
24.
The transmission electron microscope (TEM) visualization of the supermolecular structure of cold-drawn, oriented nylon 6 bulk material (bristles) by stained ultra-thin sections is reported. For evaluating the electron micrographs optical diffraction (OD) has been applied in comparison with small angle X-ray scattering (SAXS). The deformation of the spherulites was followed by polarization microscopy. In addition, investigations were carried out on commercial nylon 6 fibres. As the main result a transverse structure was revealed within the drawn samples at draw ratios between =4 and 4.5, consisting of mosaic crystals which show some lateral alignment. The structure is described by a modified layer lattice model. While the long period may increase slightly during drawing, the crystallite thickness remains almost constant. Fibres with =3.4 show a similarly oriented structure though the lateral alignment of the crystals is not so pronounced. 相似文献
25.
The bipartite entanglement in pure and mixed states of a quantum spin-1 Heisenberg dimer with exchange and uniaxial single-ion anisotropies is quantified through the negativity in a presence of the external magnetic field. At zero temperature the negativity shows a marked stepwise dependence on a magnetic field with two abrupt jumps and plateaus, which can be attributed to the quantum antiferromagnetic and quantum ferrimagnetic ground states. The magnetic-field-driven phase transition between the quantum antiferromagnetic and quantum ferrimagnetic ground states manifests itself at nonzero temperatures by a local minimum of the negativity, which is followed by a peculiar field-induced rise of the negativity observable in a range of moderately strong magnetic fields. The rising temperature generally smears out abrupt jumps and plateaus of the negativity, which cannot be distinguished in the relevant dependencies above a certain temperature. It is shown that the thermal entanglement is most persistent against rising temperature at the magnetic field, for which an energy gap between a ground state and a first excited state is highest. Besides, temperature variations of the negativity of the spin-1 Heisenberg dimer with an easy-axis single-ion anisotropy may exhibit a singular point-kink, at which the negativity has discontinuity in its first derivative. The homodinuclear nickel complex [Ni(Medpt)(-ox)(HO)](ClO)·2HO provides a suitable experimental platform of the antiferromagnetic spin-1 Heisenberg dimer, which allowed us to estimate a strength of the bipartite entanglement between two exchange-coupled Ni magnetic ions on the grounds of the interaction constants reported previously from the fitting procedure of the magnetization data. It is verified that the negativity of this dinuclear compound is highly magnetic-field-orientation dependent due to presence of a relatively strong uniaxial single-ion anisotropy. 相似文献
26.
1,3,3-Trinitroazetidine (TNAZ) has good thermal stability and low shock sensitivity, among other properties, and it has broad prospects in insensitive ammunition applications. In this study, a molecular dynamics calculation based on the ReaxFF-lg force field and multiscale shock technique (MSST) was used to simulate the shock-induced chemical reaction of TNAZ with different shock wave directions. The results showed that the shock sensitivity of TNAZ was in the order of [100] > [010] > [001]. There were significant differences in molecular arrangements in different shock directions, which affected the reaction rate and reaction path in different directions. The molecular arrangement in the [010] and [001] directions formed a “buffer” effect. The formation and cleavage of bonds, formation of small molecules and growth of clusters were analyzed to show the effect of the “buffer”. The polymerization reactions in the [010] and [001] directions appeared later than that in the [100] direction, and the cluster growth in the [010] and [001] directions was slower than that in the [100] direction. In different shock loading directions, the formation and cleavage mechanisms of the N-O bonds of the TNAZ molecules were different, which resulted in differences in the initial reaction path and reaction rate in the three directions 相似文献
27.
Alexander Marin Marc B. Taraban Vanshika Patel Y. Bruce Yu Alexander K. Andrianov 《Molecules (Basel, Switzerland)》2022,27(21)
The in vivo potency of polyphosphazene immunoadjuvants is inherently linked to the ability of these ionic macromolecules to assemble with antigenic proteins in aqueous solutions and form physiologically stable supramolecular complexes. Therefore, in-depth knowledge of interactions in this biologically relevant system is a prerequisite for a better understanding of mechanism of immunoadjuvant activity. Present study explores a self-assembly of polyphosphazene immunoadjuvant—PCPP and a model antigen—lysozyme in a physiologically relevant environment—saline solution and neutral pH. Three analytical techniques were employed to characterize reaction thermodynamics, water-solute structural organization, and supramolecular dimensions: isothermal titration calorimetry (ITC), water proton nuclear magnetic resonance (wNMR), and dynamic light scattering (DLS). The formation of lysozyme–PCPP complexes at near physiological conditions was detected by all methods and the avidity was modulated by a physical state and dimensions of the assemblies. Thermodynamic analysis revealed the dissociation constant in micromolar range and the dominance of enthalpy factor in interactions, which is in line with previously suggested model of protein charge anisotropy and small persistence length of the polymer favoring the formation of high affinity complexes. The paper reports advantageous use of wNMR method for studying protein-polymer interactions, especially for low protein-load complexes. 相似文献
28.
The paper investigates the processes of the magnetization reversal of perforated ferromagnetic films with strong anisotropy of the easy-plane type. The investigations have shown that, influenced by a current impulse passing through an antidot, an inhomogeneous magnetic structure is formed, which is accompanied by the localization of a quasiparticle with the +1 topological charge on the antidot and by an emission of a quasiparticle with a –1 charge. It is established that this scenario of the film magnetization reversal underlies a reformation of its inhomogeneous structure also if two or four antidots are present in the film, irrespective of the fact of through which antidots and in which directions the currents are passed. The results of the research obtained by using two independent methods (solving the Landau–Lifshitz–Gilbert equations and analyzing the lattice model) demonstrated good agreement between the two. It is shown that a magnetic film comprising two or four antidots can be used as a memory cell for recording data in the ternary system. 相似文献
29.
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