摘要:

A general model for diffusion in membranes is employed to illustrate that the individual contributions of diffusion relative to the membrane and self-diffusion in the pore fluid are simply related to the autocorrelation function for the instantaneous centre of mass velocity of the pore fluid and the usual autocorrelation function for the particle velocities. These results are used to analyse molecular dynamics simulation data for hindered diffusion of rigid sphere fluids in cylindrical pores over a wide range of pore fluid densities and pore sizes. Two reflection conditions, specular and diffuse scattering from the pore wall, are also investigated. The results obtained for diffuse scattering are in qualitative agreement with experimental data reported in the literature. These results also suggest that dense fluids and liquids may undergo a small, nonzero degree of slip during flow past a rigid boundary.

ISSN:0026-8976    

DOI:10.1080/00268978600101291

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A new analysis of the Fourier-transform spectrum of CF3H in the region of thev2,v5andv3+v6bands has been undertaken. The hamiltonian used here contained all symmetry allowed interaction terms up to third order in the Amat-Nielsen classification. This improved model allowed to extend assignments up toJ= 55. More than 4500 transitions, corresponding to 3499 different energy levels, have been fitted with a standard deviation of 0·0007 cm-1.

ISSN:0026-8976    

DOI:10.1080/00268978600101301

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A new definition of spectral entropy appropriate for coherence spectroscopies such as pulsed nuclear magnetic resonance spectroscopy is developed, based on an information theoretic analogue of the Von Neumann equation for entropy in quantum mechanics. It is shown that the resulting definition meets some important but previously unrecognized requirements for spectral entropy in coherence spectroscopies, and that it is possible to employ it, in a practical way, in maximum entropy signal processing. The definition is an extension of, but consistent with, the conventional one used in incoherent optical image processing.

ISSN:0026-8976    

DOI:10.1080/00268978600101311

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

On the basis of a constitutive equation appropriate for linear viscoelastic liquids, a continuum mechanics theory has been developed to consistently describe the polarized and depolarized light scattering spectra of viscoelastic liquids consisting of anisotropic molecules. The theory introduces the effect of the translation-rotational coupling in the hydrodynamic equations. It is shown that such a coupling results in reducing of the dynamic shear viscosity, the reduction of the dynamic shear viscosity thus makes the bulk viscosity dominant in determining the isotropic light scattering spectrum. The results are useful for interpreting the dynamic light scattering spectra of viscous and supercooled liquids.

ISSN:0026-8976    

DOI:10.1080/00268978600101321

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Single crystals of the title compound were studied by optical absorption and luminescence spectroscopy in the region of4A2→2E excitations. Zeeman, MCD and MCPL spectra were also recorded. Site-selective and time-resolved luminescence and excitation spectra provided information about the transfer of excitation energy. Exchange splitting patterns in the ground and excited state were obtained separately for the two inequivalent sets of dimers A and B in the crystal, and the corresponding exchange parameters were determined. The molecular orientations of the dimer units were derived from the spectroscopic data. The N-H stretching frequencies were found to play the major role as accepting modes in a multiphonon relaxation process. Numerical values were obtained for the rates of energy transfer between the sets A and B in the temperature range 1·5–100 K. They could be quantitatively accounted for by a one-phonon assisted electric dipole-dipole mechanism involving the5A1↔5B1dimer transitions.

ISSN:0026-8976    

DOI:10.1080/00268978600101331

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Nous avons mesuré des forces de raie individuelle dans les branchesP, QetRde la bandev2+v3de16O12C32S à l'aide d'un interféromètre à transformée de Fourier à haute résolution. Ces données nous ont permis de déterminer deux paramètres d'intensité significatifs à savoir la force de bandeSv/0(295 K) = 0,1474 ± 0,0090 cm-2atm-1et le coefficient α = 0,00463 ± 0,00037 du facteur correctif de Herman et WallisF= (1 + αm+ …)2.

ISSN:0026-8976    

DOI:10.1080/00268978600101341

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The temperature dependence of the mean molecular polarizability of the gases He, Ar, H2, N2, O2and C(CH3)4has been investigated experimentally with precise interferometric measurements in the temperature range 208 K ⩽T⩽ 365 K. In all cases an increase of the polarizability with increasing temperature was observed. By use of the noble gases He and Ar as internal standards it is possible to derive a relation between our results and the simple theory of Bell [1].

ISSN:0026-8976    

DOI:10.1080/00268978600101351

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Spin-lattice relaxation timesT1andT1ρfor protons in solid 2-methyl-2-propanethiol are presented. The relaxation measurements corroborate the existence of three solid-solid transitions and give some insight into their nature. The motions occurring in the respective phase modifications are discussed and their activation parameters derived.

ISSN:0026-8976    

DOI:10.1080/00268978600101361

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

We have studied the dynamical properties of triplet excitations in neat A/TCNB upon laser flash excitation in theT0←S0triplet exciton band using E.S.E. techniques. The observed signals correspond with various traps amongst which a rapid communication exists at temperatures as low as 1·2 K. Our observations exclude the possibility that the observed E.S.E. signals correspond with pairs of exciton states nor that they can be interpreted as superposition states of non-equivalent molecules.

ISSN:0026-8976    

DOI:10.1080/00268978600101371

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A theory of the lineshape of the infrared spectra of weak charge transfer complexes which emphasizes only the electrostatic interactions—namely quadrupole-induced dipole interactions—between the acceptor and donor molecules is presented and applied to the iodine-benzene complex in dilute solutions.

ISSN:0026-8976    

DOI:10.1080/00268978600101381

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor