Size matters: Nanometer‐sized gaps in aggregates of silver nanoparticles are generated by covering the nanoparticle surface with a bilayer of cetyltrimethylammonium bromide. The nanometer‐ to micrometer‐sized wells are lithographically generated on polydimethylsiloxane surfaces. The wells filled with the modified nanoparticles (see picture) and the effect of the aggregate size on SERS enhancement are investigated.
The kinetics of a proton transfer into dilute acid solutions containing natural zeolitic tuff was studied by following the
pH evolution of the liquid phase. Four different solutions with tuff contents of 9, 3, 1 and 0.5 (% wt) and three different
particle size fractions (≤ 2000 μm) were studied. The proton concentration of the solution was decreased by increasing the
zeolite amount and decreasing the particle size fraction. The proton transfer reaction was analyzed with chemical reactions
and diffusion model equations. Analysis shows that the adsorption and/or ion exchange are possible mechanisms and are expressed
by a second order reaction model. 相似文献
In order to investigate the effect of thermal oxidation temperature on tin dioxide (SnO2), tin dioxide films were obtained on quartz substrates by vacuum evaporation of tin metal. The films were characterized by X-ray diffraction (XRD) analyses, scanning electron microscopy (SEM), temperature dependent electrical resistivity measurement and optical absorption spectroscopy. The SEM images showed that the films are dense, continuous and are composed of nanoparticles and particle sizes are increased after thermal oxidation. From the X-ray measurement results, the films indicated two strong reflection peaks of tetragonal structure in the orientations of (1 0 1) and (2 0 0) at 2θ = 33.89° and 37.95°, respectively. Intensity of the peaks increased with increasing thermal oxidation temperature. We found resistivity values of about 10−4 Ω-cm. Optical absorption spectra of the films in the UV–Vis spectral range revealed that optical band gap (Eg) value of the films increases with increasing thermal oxidation temperature. 相似文献
The structural and lattice dynamical properties of TmX (X=As, P) compounds were investigated using normconserving pseudopotentials within the generalized gradient approximation correction (GGA) of Perdew–Burke–Ernzerhof (PBE) in the framework of density functional theory (DFT). The structural parameters (a0, B, B′, Ecoh) were determined through total energy and interatomic force minimization and the overall agreement was found to be good. The pressure dependence of the ratios of normalized lattice parameters a/a0, normalized volume V/V0, bulk modulus, elastic constants, Zener anisotropy factor, Poisson's ratio, Young's modulus, shear modulus, and the brittleness were presented and discussed. The thermodynamical properties such as thermal expansion, heat capacity, Debye temperature, and Grüneisen parameter were calculated employing the quasi-harmonic Debye model at different temperatures (0–1000 K) and pressures (0–30 GPa). The phonon dispersion curves and corresponding density of states (DOS) of TmX (X=As, P) were also obtained, and the salient results were interpreted. 相似文献
The Pyatov Method has been used to study the low-lying Gamow-Teller transitions in the mass region of 98 ⩽ A ⩽ 130. The eigenvalues and eigenfunctions of the total Hamiltonian have been solved within the framework of proton-neutron
quasiparticle random-phase approximation. The low-lying β decay log(ft) values have been calculated for the nuclei under consideration. 相似文献
The crystal structure of hexakis(4-phormylphenoxy)cyclotriphosphazene is determined by using X-ray diffraction and then the
molecular structure is investigated with density functional theory (DFT). X-Ray study shows that the title compound has C-H…π
interaction with phosphazene ring. The molecules in the unit cell are packed with Van der Waals and dipole-dipole interactions
and the molecules are packed in zigzag shaped. Optimized molecular geometry is calculated with DFT at B3LYP/6-311G(d,p) level.
The results from both experimental and theoretical calculations are compared in this study. 相似文献
A new compound of (C27H25N3S) has been synthesized and characterized by 1H NMR, 13C NMR, IR, UV-Visible spectroscopy, and single crystal X-ray diffraction. The compound crystallizes in the monoclinic space
group P21/c and crystals of (I) were found approximately 0.5:0.5 ratio to be twinned. The crystal structure is stabilized by N–H···N
inter molecular hydrogen bonding. In addition to the molecular geometry and dimeric structure from X-ray experiment, the optimized
molecular geometry for monomer and dimer, vibrational frequencies, atomic charges distribution, and total energies of the
title compound in the ground state have been calculated using ab initio method. Density Functional Theory (B3LYP) and Hartree-Fock
(HF) methods with basis sets 6-31G(d, p) and 3-21G were used in the calculations. Calculated frequencies are in good agreement
with the corresponding experimental data. UV-Vis absorption spectra of the compound have been ascribed to their corresponding
molecular structure and electrons orbital transitions. 相似文献
The title compound, C10H8Br2O2, consists of a tetrahydronaphthalene skeleton composed of a six‐membered ring A with arene oxide, monobromo and monohydroxy atoms in cis,cis,cis configuration held in a boat conformation and a six‐membered planar ring B, where the ring B carries monobromo atom. The repulsive interactions between the Br and OH atoms affect the topology of the tetrahydronaphthalene moieties. 相似文献
The title compound (C9H7Br3) crystallizes in the triclinic space group with Z = 2; R = 0.043 for 1518 observed reflections [I = 2σ (I)]. The average Br‐C distance is 1.974 Å, Br‐C‐C angle is 110.0°. The five‐membered ring adopts a somewhat flattened structure. The atoms C1 and C3 have opposite configurations. The whole molecule has approximate (non‐crystallographic) Cs‐symmetry. 相似文献