ISSN:0026-8976    

DOI:10.1080/00268975800100011

出版商:Taylor & Francis Group    

年代:1958

数据来源: Taylor

摘要:

This paper deals with the classification of high-resolution nuclear magnetic resonance spectra of substituted ethanes and similar molecules. In particular, the forms of the spectra for individual rotational isomers of long lifetime are compared with those appropriate to rapid internal conversion. The use of nuclear resonance data to deduce information about the rate of internal rotation is discussed in detail.

ISSN:0026-8976    

DOI:10.1080/00268975800100021

出版商:Taylor & Francis Group    

年代:1958

数据来源: Taylor

摘要:

Some simplified calculations have been performed on the electric dipole moments of pyridine, pyrimidine, pyridazine, quinoline, isoquinoline and phthalazine on the assumptions that an important contribution to the total moment results from the hybridization of the lone pair electrons of the nitrogen atoms and that the π electron moment may be calculated with a simplelcaocalculation, taking the Coulomb integral of the nitrogen αNN=αCC+0·4βCC. The deviations between theoretical and experimental results are less than 6 per cent.

ISSN:0026-8976    

DOI:10.1080/00268975800100031

出版商:Taylor & Francis Group    

年代:1958

数据来源: Taylor

摘要:

The pressure-induced rotational absorption spectrum of hydrogen has been investigated at −60°c, 25°c and 80°c in pure hydrogen and in mixtures of hydrogen with helium, argon, nitrogen and carbon monoxide. The integrated absorption coefficients have been evaluated. In mixtures of hydrogen and carbon monoxide a simultaneous rotational-vibrational transition could be observed.

ISSN:0026-8976    

DOI:10.1080/00268975800100041

出版商:Taylor & Francis Group    

年代:1958

数据来源: Taylor

摘要:

Calculations of the mean distance and mean inverse distance between the electrons in the hydrogen molecule show that a Heitler-London wave function exhibits more correlation and a molecular orbital function less correlation than a covalent-ionic wave function. Introduction of an atomic screening constant decreases the mean distance between the electrons.

ISSN:0026-8976    

DOI:10.1080/00268975800100061

出版商:Taylor & Francis Group    

年代:1958

数据来源: Taylor

摘要:

The methods developed by Prigogine and his colleagues are applied to the study of quantum mechanical systems. The density matrix is divided into a slowly varying and an oscillatory part, and asymptotic equations are established for the elements of this matrix. In the representation in which the unperturbed hamiltonian is diagonal, these equations take a particularly simple form for weakly coupled systems: the matrix elements lying on diagonals parallel to the principal diagonal undergo separate transformations. A particular case is that of the diagonal elements themselves; for these the well-known Pauli equations are obtained. As an illustrative example the problem of the frictional forces on an oscillator immersed in a thermostat is considered in detail. The frictional forces introduced by Langevin and Lorentz are special cases of this.

ISSN:0026-8976    

DOI:10.1080/00268975800100071

出版商:Taylor & Francis Group    

年代:1958

数据来源: Taylor

摘要:

Theoretical values are obtained for the thermal conductivity and the viscosity of a dense fluid of perfectly rough elastic spheres, on the basis of simple assumptions about the pair distribution functions. In this fluid angular momentum may be transferred from the bulk motion of the fluid to the rotations of the individual spheres. The rate of this transfer is given by an anti-symmetric component in the pressure tensor, and involves a coefficient of ‘rotational viscosity’, analogous to the shear viscosity arising from the symmetric component. The thermal conductivity is found to be twice as great as that for perfectly smooth spheres, while the viscosities involve the moment of inertia of the spheres as well as their mass and radius.

ISSN:0026-8976    

DOI:10.1080/00268975800100081

出版商:Taylor & Francis Group    

年代:1958

数据来源: Taylor

摘要:

A new statistical procedure is described for obtaining the thermodynamic properties of a molecular system directly as functions of the pressure. This procedure differs in principle from that suggested by Guggenheim [3] in that the members of the representative ensemble are envisaged as being in constant mechanical equilibrium with the exterior. The quantal and classical theories of petit micro-canonical and canonical ensembles of systems at constant pressure are presented, and shown to lead to the established results for perfect and imperfect gases, and for a hypothetical one-dimensional system. The conclusion that the statistical compressibility of a molecular system is essentially positive follows directly from the theory. An alternative procedure which leads to a more satisfactory form of Guggenheim's equation is also described, and its relation to the new approach is shown.

ISSN:0026-8976    

DOI:10.1080/00268975800100091

出版商:Taylor & Francis Group    

年代:1958

数据来源: Taylor

ISSN:0026-8976    

DOI:10.1080/00268975800100101

出版商:Taylor & Francis Group    

年代:1958

数据来源: Taylor

摘要:

A statistical mechanical description based on the Lennard-Jones and Devonshire model has been applied to the gas hydrates. The theory enables one to calculate dissociation pressures, compositions and heats of dissociation of several such gas hydrates. The agreement between the calctilated values and the experimental data at present available supports the theory.

ISSN:0026-8976    

DOI:10.1080/00268975800100111

出版商:Taylor & Francis Group    

年代:1958

数据来源: Taylor