摘要:

Absorption spectra of crystalline films of hydrogen and deuterium chloride and bromide at 77°khave been measured in the region 20–400 cm-1using a Michelson interferometer. The absorptions are assigned as lattice vibrations, and translational and torsional modes are distinguished. It is shown that the observed spectra are consistent with a crystalline structure of four molecules per unit cell in a planar array and approximate values of the principal intermolecular force constants are derived.

ISSN:0026-8976    

DOI:10.1080/00268976300101171

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

Absorption spectra of crystalline films of chlorine, bromine and iodine at 77°khave been measured in the region 20–400 cm-1using a Michelson interferometer. The two low-frequency bands observed for each sample are assigned as translational lattice modes, in agreement with theoretical predictions from the known crystallographic structure, and the relevant intermolecular force constants are derived. In addition, a weak absorption is observed in the region of the stretching frequency of both bromine and iodine and possible reasons for the appearance of this theoretically infra-red inactive mode are discussed.

ISSN:0026-8976    

DOI:10.1080/00268976300101181

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

The M.O. configurations of diatomic molecules MX, where M contains a partly filled 3d shell, can be related to the more usual ligand field theory. In the same way as the 3d shell of gaseous atoms generally needs one or two 4s electrons for stabilizing the ground-state, certain molecules MX can be shown to contain the number of d-like electrons characterizing M(II) and an additionalσ-electron. Comparisons are made with the occurrence of metallic bonding and 5d electrons in lanthanide compounds. Some molecules, such as TiO, pose unanswered questions, and much more experimental work would be desirable.

ISSN:0026-8976    

DOI:10.1080/00268976300101191

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

Measurements of the proton spin-lattice relaxation times as a function of concentration in aqueous alkali halide solutions are used to investigate the interactions between the ions and water molecules. A simplified model of a solution is employed in which local proton relaxation times are assigned to three different sites: those near the anion, those near the cation and those not near any ion. A procedure is worked out to calculate the local relaxation times and the number of nearest-neighbour water molecules using the data and theB-viscosity-coefficients of the solutions. Differences in the activation energies for a change in configuration about an ion relative to pure water are obtained. These indicate that the configurations of water molecules around the lithium, sodium and fluorine ions are more stable than in pure water, while those configurations about all other ions are less stable. Furthermore, the degree of stability decreases with increasing ionic radius.

ISSN:0026-8976    

DOI:10.1080/00268976300101201

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

Formal expressions are derived for the mean square dipole moment (MSM) and the mean square end-to-end (MSD) distance of polar, monosubstituted vinylic polymers. Without introducing a particular model, these expressions are written in a form which emphasizes any analogy between MSM and MSD. Three different types of characteristic coordinate systems are attached to the polymer chain instead of the usual one proposed previously by Eyring. It is shown that for the most general case no correlation will exist between MSM and MSD. For polymers with a single atom or a rigid molecular group as the polar side-chain, different possibilities for isotactic and syndiotactic structures are discussed regarding any such correlation. (This discussion may be extended to polymers where the motion of the side group is independent of the configuration of the polymer as a whole.) Further, conclusions formulated previously for MSM and concerning the cancellation of effects due to long range interactions, are shown to be valid for very particular polymers of syndiotactic structure only.

ISSN:0026-8976    

DOI:10.1080/00268976300101211

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

The energy of repulsion between hydrogen and helium atoms has been calculated by using Inui-Nordsieck-type orbitals. The results show a significant improvement in the agreement with the experimental values over that obtained by earlier calculations.

ISSN:0026-8976    

DOI:10.1080/00268976300101221

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

A suggestion by Yatsiv for enhancing the strength of double quantum signals in high resolution nuclear magnetic resonance by use of radio-frequency sidebands is examined and shown to be practical. The theory shows that double quantum techniques can be extended to weakly coupled systems of nuclei (including systems of nuclei of different isotopic species). The AX part (withJAX=5·4 c/s, δAX/2π=99·2 c/s) of the proton magnetic resonance spectrum of maltol (3-hydroxy-2-methyl-γ-pyrone) serves to confirm experimentally the quantitative theoretical treatment for weakly coupled systems. An enhancement factor of eight was observed as can be seen in figure 2.

ISSN:0026-8976    

DOI:10.1080/00268976300101231

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

The appropriateness of Pauling's theory as applied to ionic crystals and molecules has been investigated by considering alkali halides in particular. The properties considered are the cohesive energy, binding energy, vibrational frequency, rotational and vibrational constants, etc. The comparison of theory and experiment reveals that the theory is approximate because of the assumption of an over simplified potential form but is liable to yield better results if a variable value of the exponent of the inverse repulsive term is used instead of a constant value for all the alkali halides.

ISSN:0026-8976    

DOI:10.1080/00268976300101241

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

A gauge-variation method has been used to formulate expressions for the diamagnetic susceptibility and nuclear magnetic shielding in molecules entirely in terms of the ground state wave-function. The inaccuracy of the total value thus calculated is commented on, together with the equivalence of this method to Hasse-type variational calculations. McConnell's long-range approximation and Rebane's work have been discussed in the light of the present work.

ISSN:0026-8976    

DOI:10.1080/00268976300101251

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

It is shown that the isotopic separation factor,α, for a monatomic liquid in equilibrium with its vapour at low temperatures can be used to calculate the mean-square fluctuations of the intermolecular virial function. The only knowledge of the intermolecular energy that is required is the separation,σ, at which the pair potential is zero. If the additional assumption is made that this potential is of the Lennard-Jones (n, m) type then it is possible to relateαton, m, σ and the thermodynamic properties of the fluid phases. Hence recent experimental values of α for argon can be used to test potentials of the Lennard-Jones type without any assumption about the structure of the liquid.

ISSN:0026-8976    

DOI:10.1080/00268976300101261

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor