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Computer simulations based on Discrete Element Method have been performed in order to investigate the influence of interparticle interactions on the kinetics of self-assembly and the mechanical strength of nanoparticle aggregates.Three different systems have been considered.In the first system the interaction between particles has been simulated using the JKR (Johnson,Kendall and Roberts) contact theory,while in the second and third systems the interaction between particles has been simulated using van der Waals and electrostatic forces respectively.In order to compare the mechanical behaviour of the three systems,the magnitude of the maximum attractive force between particles has been kept the same in all cases.However,the relationship between force and separation distance differs from case to case and thus,the range of the interparticle force.The results clearly indicate that as the range of the interparticle force increases,the self-assembly process is faster and the work required to produce the mechanical failure of the assemblies increases by more than one order of magnitude. 相似文献
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Katherine M. Marczenko Dr. James T. Goettel Dr. Hélène P. A. Mercier Prof. Gary J. Schrobilgen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(53):12357-12366
Xenon trioxide (XeO3) forms adducts with triphenylphosphine oxide, dimethylsulfoxide, pyridine-N-oxide, and acetone by coordination of the ligand oxygen atoms to the XeVI atom of XeO3. The crystalline adducts were characterized by low-temperature, single-crystal X-ray diffraction, and Raman spectroscopy. Unlike solid XeO3, which detonates when mechanically or thermally shocked, solid (C5H5NO)3(XeO3)2, [(C6H5)3PO]2XeO3, and [(CH3)2SO]3(XeO3)2 are insensitive to mechanical shock. The [(CH3)2SO]3(XeO3)2 adduct slowly decomposes over several days to (CH3)2SO2, Xe, and O2. All three complexes undergo rapid deflagration when ignited by a flame. Both [(C6H5)3PO]2XeO3 and (C5H5NO)3(XeO3)2 are room-temperature stable and the [(CH3)2CO]3XeO3 complex dissociates at room temperature to form a stable solution of XeO3 in acetone. The xenon coordination sphere of [(C6H5)3PO]2XeO3, a distorted square-pyramid, provides the first example of a five-coordinate XeO3 complex with only two Xe- - -O adduct bonds. The xenon coordination spheres of the remaining adducts are distorted octahedra, comprised of three Xe- - -O secondary bonds that are approximately trans to the primary Xe−O bonds of XeO3. Quantum-chemical calculations were used to assess the nature of the Xe- - -O adduct bonds, which are described as predominantly electrostatic bonds between the nucleophilic oxygen atoms of the bases and the σ-holes of the electrophilic xenon atoms. 相似文献
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James T. Goettel Dr. Kazuhiko Matsumoto Dr. Hélène P. A. Mercier Prof. Gary J. Schrobilgen 《Angewandte Chemie (International ed. in English)》2016,55(44):13780-13783
The potent oxidizer and highly shock‐sensitive binary noble‐gas oxide XeO3 interacts with CH3CN and CH3CH2CN to form O3XeNCCH3, O3Xe(NCCH3)2, O3XeNCCH2CH3, and O3Xe(NCCH2CH3)2. Their low‐temperature single‐crystal X‐ray structures show that the xenon atoms are consistently coordinated to three donor atoms, which results in pseudo‐octahedral environments around the xenon atoms. The adduct series provides the first examples of a neutral xenon oxide bound to nitrogen bases. Raman frequency shifts and Xe?N bond lengths are consistent with complex formation. Energy‐minimized gas‐phase geometries and vibrational frequencies were obtained for the model compounds O3Xe(NCCH3)n (n=1–3) and O3Xe(NCCH3)n?[O3Xe(NCCH3)2]2 (n=1, 2). Natural bond orbital (NBO), quantum theory of atoms in molecules (QTAIM), electron localization function (ELF), and molecular electrostatic potential surface (MEPS) analyses were carried out to further probe the nature of the bonding in these adducts. 相似文献
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在一系列H模放电条件下,建立了一个旨在研究等离子体温度分布剖面不变性的数据库。介绍了数据库建立过程中要解决的关键问题和所用软件,对等离子体温度分布剖面不变性及芯部约束与边缘参数的关系进行了研究。 相似文献
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Ultraviolet Photolysis Studies on XeO4 in Noble‐Gas and F2 Matrices and the Formation and Characterization of a New XeVIII Oxide, (η2‐O2)XeO3 下载免费PDF全文
Thomas Vent‐Schmidt James T. Goettel Prof. Dr. Gary J. Schrobilgen Prof. Dr. Sebastian Riedel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(31):11244-11252
The photolytic behavior of the thermochemically unstable xenon(VIII) oxide XeO4 was investigated by UV irradiation in noble‐gas and F2 matrices. Photolysis of Xe16O4 or Xe18O4 in noble‐gas matrices at 365 nm yielded XeO3 and a new xenon(VIII) oxide, namely, (η2‐O2)XeO3, which, along with XeO4, was characterized by matrix‐isolation IR spectroscopy and quantum‐chemical calculations. Calculations of the UV spectrum showed that the photodecomposition is induced by an n→σ* transition, but the nature of the excitation differs when different light sources are used. There is strong evidence for the formation of mobile 1D excited O atoms in the case of excitation at 365 nm, which led to the formation of (η2‐O2)XeO3 by reaction with XeO4. Matrix‐isolation IR spectroscopy in Ne and Ar matrices afforded the natural‐abundance xenon isotopic pattern for the ν3(T2) stretching mode of Xe16O4, and 18O enrichment provided the 16O/18O isotopic shifts of XeO4 and (η2‐O2)XeO3. 相似文献
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Ralf Koppert Dirk Goettel Olivia Freitag-Weber Guenter Schultes 《Solid State Sciences》2009,11(10):1797-1800
Diamond like carbon (DLC) coatings are well established for multiple applications. The electrical conductivity of DLC or amorphous carbon can be influenced by several orders of magnitude via doping with different metals. Depending on the deposition process hydrogen may be incorporated as well, thereby decreasing the conductivity. Recent investigations of DLC disclose nice piezoresistive properties.Our work was focused on Ni:a-C:H thin films on different substrates by reactive sputtering from a nickel target. Several carbon precursors were added to the sputtering gas to create an amorphous carbon hydrogen network with embedded crystal clusters. In order to optimize the piezoresistive properties we varied various process parameters. The piezoresistive response was monitored by measuring the resistance change during bending. Our Ni:a-C:H films develop gauge factors of approx. 12 in a wide range of process parameters.For sensor applications the temperature coefficient of resistance (TCR) is important as well. It depends on the metal concentration in the thin film and can be adjusted by the concentration of the incorporated nickel. It can be set to approximately zero in a wide temperature range of 80–400 K. The combination of a high gauge factor and a very small TCR is achieved and described in this paper.XRD measurements reveal nickel or nickel carbide clusters with diameters of approx. 8–30 nm depending on the metal concentration. The clusters crystallize in the hexagonal hcp structure which could be transformed into the cubic fcc structure of nickel by thermal annealing in a vacuum. 相似文献
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Marius Gerlach Sophie Monninger Domenik Schleier Dr. Patrick Hemberger Dr. James T. Goettel Prof. Dr. Holger Braunschweig Prof. Dr. Ingo Fischer 《Chemphyschem》2021,22(21):2164-2167
We investigate NCl3 and the NCl2 radical by photoelectron-photoion coincidence spectroscopy using synchrotron radiation. The mass selected threshold photoelectron spectrum (ms-TPES) of NCl3 is broad and unstructured due to the large geometry change. An ionization energy of 9.7±0.1 eV is estimated from the spectrum and supported by computations. NCl2 is generated by photolysis at 213 nm from NCl3 and its ms-TPES shows an extended vibrational progression with a 90 meV spacing that is assigned to the symmetric N−Cl stretching mode in the cation. An adiabatic ionization energy of 9.94 ± 0.02 eV is determined. 相似文献
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