摘要:

The structure factorS(Q) has been measured for liquid nitrogen at 77 K by neutron diffraction at four wavelengths. The effects of Placzek corrections on the self [1, 2] and interference [3] components of the observed differential scattering cross-sections at 0·35, 0·7, 0·84 and 1·06 Å [4] have been investigated. Effective molecular masses and internuclear bond lengths have been obtained by fitting a modified Placzek model to the observed data. It is concluded that after correction the different structure factors agree satisfactorily within the statistical errors of the measurements and the internuclear bond length is close to that measured in the gas phase.

ISSN:0026-8976    

DOI:10.1080/00268978000100451

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The depolarized scattered light intensity from supercooled benzyl benzoate has been analysed in the whole spectral range for a 90° scattering angle with a Fabry-Perot and an intensity correlation technique. In particular, a detailed analysis of the central part of the spectrum of both polarized and depolarized intensities, is carried out. Our results are consistent with the local order theory and allow the experimental determination of the relaxation times and coupling coefficients of the tensorial variables introduced in that theory.

ISSN:0026-8976    

DOI:10.1080/00268978000100461

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

A theoretical model of vibrational dephasing of Raman active ions in aqueous electrolyte solutions is presented in which a probe ion is coupled to the bath by direct ion-solvent and ion-ion interactions. Expression for the vibrational width in terms of concentrations and efficiencies of the vibrational frequency modulation by ion-perturber interactions is given in the fast modulation scheme. The observed linear concentration dependence of the vibrational dephasing width of thev1(A'1) mode of NO3-in aqueous solutions is reasonably well explained from this model, and efficiencies of the dephasing paths through NO3--water hydrogen bonding interaction and contact NO3--cation pair formation interaction are estimated. Anions in the solution give only a secondary effect to nitrate vibrational dephasing because of interionic repulsive forces.

ISSN:0026-8976    

DOI:10.1080/00268978000100471

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The π-bond model is applied to the calculation of the proton chemical shifts of a range of benzenoid hydrocarbons. The simple calculations give results which compare well with experiment and with calculations based on the ring current model. Least squares fitting of the predicted chemical shifts to the observed values can give an indication of the occurrence of local aromatic groups in larger molecules. This procedure also yields an empirically adjusted estimate of the anisotropy in the molar magnetic susceptibility from the experimental proton chemical shifts. A simple criterion for aromaticity is also given. The overall results suggest that there is no need to associate a special ring current attribute to π conjugation in aromatic molecules.

ISSN:0026-8976    

DOI:10.1080/00268978000100481

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

A detailed numerical study has been made of the convergency of second-and approximate second-order multiconfigurational Hartree-Fock procedures. Calculations were performed on the excited 2p21Sstate of Be and on the lowest states of3Σg-,1δg,1Σg+,1Δgand3Δgsymmetry in O2. The O2calculations included all configurations that could be formed from doubly occupied core orbitals with eight electrons in the valence orbitals, 3σg, 1πu, 1πgand 3σu. All second-order calculations converged in between 4 and 6 iterations even for a case where approximate second-order procedures did not converge.

ISSN:0026-8976    

DOI:10.1080/00268978000100491

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

In the framework of the classical statistical mechanics of fluids, it is shown that any truncated approximation to a thermodynamical quantity can be made much more accurate in a larger region of physical parameters, provided one uses a variational procedure for determining the best way of splitting the potential into a long and short range part. The usefulness and the limitations of this method are illustrated through its application to restricted symmetric primitive models.

ISSN:0026-8976    

DOI:10.1080/00268978000100501

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The measured relaxation infrared chemiluminescence method has been used to determine the relative primary rate constants for formation of deuterium fluoride in vibrational levelsv′ = 2 to 12, and to show that the most populated level isv′ = 10. These results lead to a figure of 62 per cent for the fraction of available energy initially entering vibration. This value is approximately 5 per cent higher than the corresponding result for the H/F2system. The deuterium fluoride energy distribution is in conflict with various previous calculations. New trajectory calculations using the LEPS surface previously found to be most appropriate for the H/F2system suggest thev′ = 9 should be the most populated level. It was found that adjustment of the Sato parameters of this surface led to an improvement in the agreement between experimental and calculated distributions. However, use of this modified surface for the H/F2reaction did not give as good a fit with the experimental vibrational distribution as that used previously. This finding, that a common LEPS surface did not lead to the best description of both the H/F2and D/F2cases, is suggested as being due to a limitation of the classical trajectory method.

ISSN:0026-8976    

DOI:10.1080/00268978000100511

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

ISSN:0026-8976    

DOI:10.1080/00268978000100521

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

ISSN:0026-8976    

DOI:10.1080/00268978000100531

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Equilibrium optical properties of liquid carbon disulphide (CS2), i.e. its refractive index, Kerr constant and depolarized light scattering intensity are calculated using two models of optical response of the fluid. The first one, the point polarizability approximation (PPA) assumes that a point dipole, proportional to the total polarizability, is induced in each molecule. The second one, the point atomic polarizability approximation (PAPA) assumes that point dipoles are induced in individual atomic sites.

ISSN:0026-8976    

DOI:10.1080/00268978000100541

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor