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91.
Varadhi GovindaPankaj Attri P. Venkatesu P. Venkateswarlu 《Journal of Molecular Liquids》2011,164(3):218-225
To understand the molecular interactions between newly synthesized ammonium ionic liquids (ILs) and highly polar solvent dimethylsulfoxide (DMSO), precise measurements such as densities (ρ), ultrasonic sound velocities (u) and viscosities (η) have been performed over the whole composition range at temperature ranging from 298.15 to 308.15 K and at atmospheric pressure. The ILs investigated in the present study included diethyl ammonium acetate ([Et2NH][CH3COO], DEAA) and triethyl ammonium acetate ([Et3NH][CH3COO], TEAA). Further, to gain some insight into the nature of molecular interactions in these mixed solvents, we predicted the excess molar volume (VE), the deviation in isentropic compressibilities (ΔKs) and deviation in viscosity (Δη) as a function of the concentration of IL using the measured properties of ρ, u and η, respectively. Redlich-Kister polynomial was used to correlate the results. The intermolecular interactions and structural effects were analyzed on the basis of the measured and the derived properties. A qualitative analysis of the results is discussed in terms of the ion-dipole, ion-pair interactions, and hydrogen bonding between ILs and DMSO molecules and their structural factors. 相似文献
92.
A theoretical study is given of magnon-phonon interactions in antiferromagnetic materials. The roles of magnons and phonons as heat carriers and as sources of thermal resistance have been taken into consideration. The exact collision operator which represents the magnon-phonon interactions involved in the transport Boltzmann equations has been replaced by a model operator which possesses the same important properties. The effect of other scattering processes that either phonons or magnons are involved has also been investigated. A new expression for the thermal conductivity has been derived. It includes terms which represent both Normal and Umklapp magnon-phonon processes. The results obtained by using the new expression agree quantitatively with the experimental measurements on Fe Cl2 相似文献
93.
This work is motivated by the recent developments in online minerals analysis in the mining and minerals processing industry via nuclear quadrupole resonance (NQR). Here we describe a nuclear magnetic resonance (NMR) and NQR study of the minerals tennantite (Cu12As4S13) and tetrahedrite (Cu12 Sb4S13). In the first part NQR lines associated with 75As in tennantite and 121,123Sb isotopes in tetrahedrite are reported. The spectroscopy has been restricted to an ambient temperature studies in accord with typical industrial conditions. The second part of this contribution reports nuclear quadrupole-perturbed NMR findings on further, only partially characterised, metal arsenides. The findings enhance the detection capabilities of NQR based analysers for online measurement applications and may aid to control arsenic and antimony concentrations in metal processing stages. 相似文献
94.
S.M. Driver 《Surface science》2007,601(2):510-517
We have used a novel fibre-optic low-energy electron diffraction (FO-LEED) instrument, capable of low flux measurements that minimise electron beam damage to surface overlayers, to study methanethiolate (CH3-S-) structural phases formed on Cu{1 1 1} at temperatures between 110 and 300 K. Three structural phases were seen: a (√3 × √3)R30° phase that forms at 110-140 K; a (4 × 4) phase which was observed transiently at 110 K; and a pseudo-{1 0 0} reconstructed phase which forms at room temperature. We discuss these in the context of previous studies of this system, and demonstrate the ability of the FO-LEED instrument to record high-quality LEED patterns and intensity data from a strongly beam-sensitive surface. 相似文献
95.
J.-J. Shi B.C. Sanders S.-H. Pan 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,4(1):113-119
We calculate the electron-phonon scattering rate for an asymmetric double barrier resonant tunneling structure based on dielectric
continuum theory, including all phonon modes, and show that interface phonons contribute much more to the scattering rate
than do bulk-like LO phonons for incident energies which are approximately within an order of magnitude of the Fermi energy.
The maximum scattering rate occurs for incident electron energies near the quantum well resonance. Subband nonparabolicity
has a significant influence on electron-phonon scattering in these structures. We show that the relaxation time is comparable
to the dwell time of electrons in the quantum well for a typical resonant tunneling structure.
Received: 23 December 1997 / Revised: 24 March 1998 / Accepted: 9 March 1998 相似文献
96.
F.E. van Dorsselaer G. Nienhuis 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,2(2):175-180
We present a scheme for stochastic quantum-state diffusion (QSD) with adaptive noise to calculate the time evolution of an
arbitrary observable of an open system. The method is based on the fact that the observable is much less sensitive to adaptive
noise than to noise with a random phase. Hence, the individual realisations of the expectation value of the observable stay
closer to the average evolution and fewer realisations are required to obtain the ensemble average. This is illustrated by
applying QSD to a driven two-level system using both randomly phased and adaptive noise. Applying QSD with adaptive noise
to an undriven two-level system enables us to derive a deterministic Schr?dinger equation that produces the exact evolution
of an arbitrary observable.
Received: 31 July 1997 / Received in final form: 12 February 1998 / Accepted: 13 March 1998 相似文献
97.
Oleg Lisovyy 《Letters in Mathematical Physics》2006,77(1):63-81
We introduce and study a family of quantum fields, associated to δ-interactions in one dimension. These fields are analogous to holonomic quantum fields of Sato et al. in Holonomic quantum fields I–V (Publ. RIMS, Kyoto University, 14: 223–267, 1978; 15: 201–278, 1979; 15: 577–629, 1979; 15: 871-972, 1979; 16: 531–584, 1979). Corresponding field operators belong to an infinite-dimensional representation of the group
in the Fock space of ordinary harmonic oscillator. We compute form factors of such fields and their correlation functions, which are related to the determinants of Schroedinger operators with a finite number of point interactions. It is also shown that these determinants coincide with tau functions, obtained through the trivialization of the det*-bundle over a Grassmannian associated to a family of Schroedinger operators. 相似文献
98.
S. Capstick A. Švarc L. Tiator J. Gegelia M. M. Giannini E. Santopinto C. Hanhart S. Scherer T. -S. H. Lee T. Sato N. Suzuki 《The European Physical Journal A - Hadrons and Nuclei》2008,35(3):253-266
The physical meaning of bare and dressed scattering matrix singularities has been investigated. Special attention has been
attributed to the role of the well-known invariance of the scattering matrix with respect to the field transformation of the
effective Lagrangian. Examples of evaluating bare and dressed quantities in various models are given. 相似文献
99.
Sakuma Y Imai M Yanagisawa M Komura S 《The European physical journal. E, Soft matter》2008,25(4):403-413
We report the adhesion of binary giant vesicles composed of two types of phospholipids, one has negative spontaneous curvature which tends to bend toward the head group and the other has zero spontaneous curvature. In a homogeneous one-phase region, the giant vesicles do not adhere to each other, whereas in a coexisting two-phase region, the giant vesicles show adhesion. A fluorescence microscope observation reveals that the adhesion takes place through the domains rich in phospholipids having negative spontaneous curvature. We propose a phase separation induced hemifusion model where two apposed monolayers of adjacent vesicles are hemifused in order to reduce the bending energy of monolayers with negative spontaneous curvature and the boundary energy between the domains and matrix. We provide a strong evidence for the hemifusion model by lipid transfer experiments. 相似文献
100.
The interface-optical-propagating (IO-PR) mixing phonon modes of a quasi-zero-dimensional (QOD) wurtzite cylindrical quantum dot (QD) structure are derived and studied by employing the macroscopic dielectric continuum model. The analytical phonon states of IO-PR mixing modes are given. It is found that there are two types of IO-PR mixing phonon modes, i.e. p-IO//z-PR mixing modes and the z-IO//p-PR mixing modes existing in QOD wurtzite QDs. And each IO-PR mixing modes also have symmetrical and antisymmetrieal forms. Via a standard procedure of field quantization, the Frohlich Hamiltonians of electron-(IO-PR) mixing phonons interaction are obtained. Numerical calculations on a wurtzite GaN cylindrical QD are performed. The results reveal that both the radial-direction size and the axial-direction size as well as the dielectric matrix have great influence on the dispersive frequencies of the IO-PR mixing phonon modes. The limiting features of dispersive curves of these phonon modes are discussed in depth. The phonon modes "reducing" behavior of wurtzite quantum confined systems has been observed obviously in the structures. Moreover, the degenerating behaviors of the IO-PR mixing phonon modes in wurtzite QOD QDs to the IO modes and PR modes in wurtzite Q2D QW and QID QWR systems are analyzed deeply from both of the viewpoints of physics and mathematics. 相似文献