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1.
2.
Structures of ionic liquids (ILs) 1-decyl-3-methylimidazolium bis(trifluoromethanesulfonyl)azanide ([C10mim][TFSA]) and 1-decyl-dimethylimidazolium bis(trifluoromethanesulfonyl)azanide ([C10(mim)2](TFSA)2) in different-sized mica slits have been investigated using molecular dynamics simulations. Ion density and angular distributions for monocationic IL [C10mim][TFSA] were analysed to elucidate the IL structures under different surface charges and especially their changes in the direction perpendicular to the surfaces. [C10mim][TFSA] formes in bilayers, compatible with existing models of ILs with long alkyl chains. For dicationic IL [C10(mim)2](TFSA)2, cations adjacent to the mica surface tend to stay parallel to the surface with both positively charged rings absorbed. While near the centre of the slit, dications show the weak tendency of orientation distribution, more random than [C10mim]+ ions. Structures of [C10(mim)2](TFSA)2 cannot be described by bilayer models. Additionally, the in-plane arrangement of [C10mim][TFSA] is more ordered when K+ ions completely neutralise the negative charge of the mica surface, and [C10mim]+ ions tend to be located in hexagonal mica lattices with two aluminium atoms in replacement of silicon atoms. [TFSA]? ions are constrained by the neighbouring K+ ions absorbed onto mica lattices. 相似文献
3.
This paper presents particulate and layered materials used in industry with at least one dimension under 500 nm. The objective is to bring to the attention of researchers areas of investigation where new properties and phenomena may manifest. The most relevant materials are natural and synthetic platelets and spherical and coated silica particles. 相似文献
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Atomic force microscopy (AFM) has been applied to visualize expanded linear chain and compact crystalline conformations of ultrahigh molecular weight polyethylene (PE) molecules deposited on mica and graphite from diluted solutions at elevated temperatures. Isolated PE chains are visualized on mica with the apparent negative AFM height and the contour length much shorter than the molecular length. The chain conformations have both the kinked random‐coil sites and the sites of the unexpectedly large two‐dimensional expansion. The crystalline conformations on mica are small single‐molecule rod‐like nanocrystallites and the isolated block‐type “edge‐on” nanolamellae comprising several PE molecules. Noticeable fluctuations of the fold length in the range of approximately 10–20 nm around the averaged value of about 15 nm are observed for nanocrystallites and on tips of some nanolamellae. The explanation of the experimentally observed features of chain surface conformations on mica is proposed. It implies the immobilization of PE molecules in the nm‐thickness salt layer formed on mica surface at ambient conditions after PE deposition and the presence along the chain of multiple expanded chain folds. Only isolated lamellae and lamellar domains of a monolayer height are observed on graphite samples. The substrate/polymer epitaxial incommensurability important for the observation of the PE linear chain surface conformations is discussed from the comparison of the results obtained for mica and graphite, the coil‐to‐crystal intramolecular transformation is assumed to be inhibited on mica surface. The slow disintegration of the original gel structure of PE stock‐solution used for the high‐temperature depositions was found to result in the characteristic large‐scale morphological heterogeneity of the samples. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 766–777, 2010 相似文献
6.
O. A. Bernaola P. J. Meoli G. Saint-Martin I. Nemirovsky G. Olivera 《Radiation measurements》1997,28(1-6):123-126
Tracks of 49 MeV 35Cl ions in muscovite mica were analyzed by transmission electron microscopy up to 10 Å resolution applying the track replica method. The enlargement of the track diameter is measured as a function of etching time. The track shape evolution shows circular tracks for very short etching times. By increasing the etching time the tracks gradually become ovals. For longer etching times, tracks show the characteristic rhombic shape of the bulk region. A non monotonous decrease of the track velocity vs. radius is reported. Formation of a low velocity shell in the intermediate region between the central amorphous zone and the non-perturbed crystalline lattice is suggested. 相似文献
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Application of multiple-beam white-light fringes for measuring the refraction and dispersion of mica
S.Y. El-Zaiat 《Optics & Laser Technology》1997,29(8):495-500
Multiple-beam white-light interference fringes are applied to measure the two refractive indices of a mica sample and their dispersion across the visible spectrum. In addition, the mica birefringence and its dispersion are measured. A mica sample of dimensions 2 × 5 mm2 and an immersion liquid of nearly the same refractive index are used. Only a single shot interferogram is needed to measure all the aforementioned parameters. Cauchy's and a modified single-term Sellmeier dispersion formula are used for fitting the experimental data and extracting the parameters required. 相似文献
9.
[MnIIxFeII1?x(H2O)6][LiFeIII(ox)3] (with 0 ≤ x ≤ 1) crystallizes in the space group P31c with a = 9.341(3) Å, c = 10.226(3) Å, c/a = 1.0947, and V = 772.8(5) Å3 for Z = 2. The compound has a layered structure with two enantiomeric layers per unit cell. The layers are built up by an iron and lithium oxalate framework with intercalated M(II)-water octahedra of the formula [MnIIxFeII1?x(H2O)6][MIMIII(ox)3]. The value of x cannot be specified at present. The structure displays intermolecular hydrogen bonding between the layers. 相似文献
10.
Yang Xin Amir Ardalan Zargariantabrizi Guido Grundmeier Adrian Keller 《Molecules (Basel, Switzerland)》2021,26(16)
DNA origami nanostructures (DONs) are promising substrates for the single-molecule investigation of biomolecular reactions and dynamics by in situ atomic force microscopy (AFM). For this, they are typically immobilized on mica substrates by adding millimolar concentrations of Mg2+ ions to the sample solution, which enable the adsorption of the negatively charged DONs at the like-charged mica surface. These non-physiological Mg2+ concentrations, however, present a serious limitation in such experiments as they may interfere with the reactions and processes under investigation. Therefore, we here evaluate three approaches to efficiently immobilize DONs at mica surfaces under essentially Mg2+-free conditions. These approaches rely on the pre-adsorption of different multivalent cations, i.e., Ni2+, poly-l-lysine (PLL), and spermidine (Spdn). DON adsorption is studied in phosphate-buffered saline (PBS) and pure water. In general, Ni2+ shows the worst performance with heavily deformed DONs. For 2D DON triangles, adsorption at PLL- and in particular Spdn-modified mica may outperform even Mg2+-mediated adsorption in terms of surface coverage, depending on the employed solution. For 3D six-helix bundles, less pronounced differences between the individual strategies are observed. Our results provide some general guidance for the immobilization of DONs at mica surfaces under Mg2+-free conditions and may aid future in situ AFM studies. 相似文献