Index of content:
Volume 26, Issue 4, 01 April 1957
26(1957); http://dx.doi.org/10.1063/1.1743391View Description Hide Description
The electronic spectra of a series of cyclic unsaturated radicals and ions containing from three to eight carbon atoms have been calculated by a semiempirical molecular orbital method.
Spectra of the Alkali Halides. III. Electronic Spectra of Lithium Chloride, Lithium Bromide, and Lithium Iodide26(1957); http://dx.doi.org/10.1063/1.1743392View Description Hide Description
The ultraviolet absorption spectra of the molecules LiCl, LiBr, and LiI have been observed in the quartz region. These spectra, which appear as continua with associated diffuse bands, have been interpreted as arising from excitations to two excited states of the molecules. The symmetries and potential curves for these states are discussed.
Potentiometric Titration, Association Phenomena, and Interaction of Neighboring Groups in Polyelectrolytes26(1957); http://dx.doi.org/10.1063/1.1743393View Description Hide Description
The partition functions and potentiometric titration equations are calculated for a number of types of polyelectrolytes, including polyampholytes and other electrolyticcopolymers. The effects of the interaction between neighboring groups and of the electrostatic potential of the macromolecule as a whole are both accounted for independently, by treating the ionized macromolecule as a separate phase in equilibrium with the surrounding solution.
The possibility of association of monovalent cations with the acidic groups of polyacids is discussed, following the derivation of the titration equations for both the H+ ion and the associating metallic cation.
26(1957); http://dx.doi.org/10.1063/1.1743394View Description Hide Description
The microwave spectrum of sulfuryl fluoride, SO2F2, has been reinvestigated. The spectra of the S32 and S34 species in natural abundance have been analyzed, and the structure has been determined with the aid of the S34isotope shift. The correction for zero‐point vibration was shown to be small. The structural parameters are: r SO=1.405±0.003 A, r SF=1.530±0.003 A, <OSO=123°58′±12′, and <FSF=96°7′±10′. The molecular dipole moment is 1.110±0.015 Debye units. A number of satellite lines were observed and assigned to excited vibrational states. Some anomalies in the measuredrotational constants for the excited states have been interpreted in terms of a Coriolis‐type interaction between the fundamentals ν4(A 1) and ν5(A 2). From an analysis of this interaction the frequency of the hitherto unobserved ν 4 (A 1) fundamental was found to be 388±15 cm—1.
26(1957); http://dx.doi.org/10.1063/1.1743395View Description Hide Description
Precise experimental data are compared with precise theoretical values for the detonation velocities of several gaseous mixtures of cyanogen and oxygen. The results of this comparison show that these detonation processes are pathological in the sense of the theory of Kirkwood and Wood. Because of the lack of chemical kinetic data, it is not possible to calculate correct detonation velocities for these pathological detonations. Therefore, the determination of detonation velocities is not a worthwhile method for the determination of precise values of thermodynamic properties in mixtures of cyanogen and oxygen.
26(1957); http://dx.doi.org/10.1063/1.1743396View Description Hide Description
The infrared spectrum of solid nitrous oxide has been obtained at 80°K. Several bands due to isotopic species are seen. In contrast with CO2, no evidence is observed for splitting due to intermolecular coupling or for reflection peaks in the spectrum.Spectral features assigned to torsional lattice motions (with fundamentals at 80 and 91 cm—1) and to translational lattice motions (as broadening of v 3) are present.
26(1957); http://dx.doi.org/10.1063/1.1743398View Description Hide Description
Data are presented for the solubility of hydrogen and deuterium in eight nonpolar solvents from —25°C to 35°C, and show that deuterium is about 2.5% more soluble. The data are accurate to 0.1% and correlate successfully with the solubility parameter of the solvent. The various thermodynamic functions are calculated.
26(1957); http://dx.doi.org/10.1063/1.1743399View Description Hide Description
A theorem of corresponding states for polymers (r‐mers) is derived for condensed states (liquid and solid). This theorem permits to correlate the thermodynamic properties of an homologous series of r‐mer molecules. It gives satisfactory results when applied to the n hydrocarbons series.
26(1957); http://dx.doi.org/10.1063/1.1743400View Description Hide Description
The energy of interaction between two hydrogen molecules and between a hydrogen atom and a hydrogen molecule are calculated using a new method1 for approximating the 3‐ and 4‐center integrals. The results are in good agreement with previous calculations of Margenau and with existing experimental data. The multiple exchange and zeroeth order perturbation make our calculations somewhat complicated. Although good results were obtained by de Boer, who neglected these terms, the success of such a procedure depends on a fortuitous cancellation of errors. Following de Boer's procedure for the case of a hydrogen atom‐hydrogen molecule interaction, we obtained very poor results.
26(1957); http://dx.doi.org/10.1063/1.1743401View Description Hide Description
The effect of induced atomic quadrupole moments upon the refractive index is investigated using Maxwell's macroscopic field equations. For this purpose a new frequency‐dependent parameter δ is introduced which is characteristic of a homogeneous isotropic dielectric and is proportional to what might be called the quadrupolarizability. In order to obtain a dispersion formula a quantum mechanical calculation is made of the induced electric and magnetic dipole and electric quadrupole moments. The results suggest the general form to use for the classical field quantities P, M, Q (electric and magnetic dipole and electric quadrupole moments per unit volume respectively) for the classical theory of crystal optics in a higher approximation.
26(1957); http://dx.doi.org/10.1063/1.1743402View Description Hide Description
The infrared and Raman spectra of trans‐difluorodichloroethylene (t‐C2F2Cl2) have been measured and an assignment of fundamentals made. They are, in cm—1: 1707, 1186, 632, 425, and 288 in ag ; 333 and 140 in au ; 529 in bg ; and 1190, 892, 426, and 175 in bu. A table of thermodynamic functions is given for the molecule in the ideal gaseous state.
26(1957); http://dx.doi.org/10.1063/1.1743403View Description Hide Description
Calculations have been made for the general cases of a linear polar molecule interacting with the following foreign molecules: monatomic, linear nonpolar, and linear polar. The interactions of importance are the first‐order London dispersion force for the first two cases and the combined dipole‐quadrupole, quadrupole‐quadrupole, and first‐order London dispersion forces for the third case. In the case of OCS with He, O2, and N2O the calculations yield 3.22, 5.41, and 7.41 A, respectively, in reasonable agreement with experiment.
26(1957); http://dx.doi.org/10.1063/1.1743404View Description Hide Description
An x‐ray diffraction study has been made of the cubic phase of ice previously reported by König from electron diffraction work. Cubic ice could be obtained only by direct crystallization from the vapor onto surfaces at low temperature. Condensation rate and surface conditions are critical variables in the formation of cubic ice. Powdered mixtures of cubic and hexagonal ice were studied at —190° and —130°C. The powder x‐ray patterns confirm the diamondstructure for the oxygen atoms; the cubic cell edge is a=6.37 ±0.02 A at —190°C.
26(1957); http://dx.doi.org/10.1063/1.1743405View Description Hide Description
The thermal conductivity of liquid gallium does not appear to have heretofore been measured. The method employed involved a comparison with the known thermal conductivity of mercury. The two liquids were sealed in two thin‐walled glass tubes (30 cm long, 10 mm bore), the upper ends being inserted vertically through the bottom of a boiler containing boiling water. The tubes were coated to secure the same thermal emissivity. Two thermocouple loops which could be moved along the tubes served to establish points having the same temperature on the two tubes. The ratio of the squares of the lengths from the thermocouple junctions to the bottom of the boiler gave 3.51±0.03 as the relative thermal conductivity of gallium to that of mercury, or 0.336±0.005 watt/cm (°C) as the thermal conductivity of gallium between 30° and 100°C, based upon 0.0958 for mercury.
It was found possible to supercool liquid gallium to —28°C, or 58°C below its melting point, by exposing small drops on paper to a slowly decreasing temperature in a deep‐freeze chamber with a circulating atmosphere.
An attempt to measure the negative pressure of gallium proved disappointing, for it was found that gallium does not ``wet'' the wall of an evacuated tube. With a partial evacuation, low negative pressures were measured which decreased (like water) as the melting point was approached.
26(1957); http://dx.doi.org/10.1063/1.1743406View Description Hide Description
The lattice dynamics of hexagonal close‐packed metals has been investigated, the assumption being made that the atoms interact with central forces. Atomic force constants are related to the elastic constants by the method of homogeneous deformation in which the contribution of the electron gas to the elastic constants is assumed to arise from an isotropic volume‐dependent term in the energy. Relations are given for the propagation of acoustical waves in hexagonal crystals which permit calculation of the elastic constants from ultrasonic pulse velocity measurements.
26(1957); http://dx.doi.org/10.1063/1.1743407View Description Hide Description
The infrared spectrum of di‐deuteroketene is reported along with a number of fundamentals which were observed for CHDCO. The spectrum of CH2CO has been re‐examined and many new overtones have been assigned. A normal coordinate analysis tends to confirm the assignments through a successful calculation of the observed frequencies for CHDCO.
26(1957); http://dx.doi.org/10.1063/1.1743408View Description Hide Description
The complete mass spectrum of pentaborane‐d 9 and a partial mass spectrum of pentaborane‐d 8 have been calculated from the spectra of a series of samples of different hydrogen content. The vapor pressure for pentaborane‐d 9 containing 3.9% of the B5D8H species can be expressed by the equation log10 P mm=9.46916 — 0.0028783T — 1870.70/T over the temperature of — 25°C to +56°C. The melting point is — 47.0°C. By way of comparison the vapor pressure equation for pentaborane is log10 P mm=9.49191 — 0.0028956T — 1881.29/T; the melting point is — 46.8°C.
26(1957); http://dx.doi.org/10.1063/1.1743409View Description Hide Description
Diffusion coefficients for nickel in polycrystalline and monocrystalline nickel oxides have been measured by the surface‐activity method from 1000 to 1400°C in air. Within experimental uncertainty the values D=4.4×10—4 exp(—44.2/RT) fit both cases. These results indicate that the oxidation of nickel under comparable conditions of T and P proceeds via lattice diffusion of Ni through NiO.
26(1957); http://dx.doi.org/10.1063/1.1743411View Description Hide Description
Mayer's expressions for the ionic activity coefficient and osmotic pressure of an electrolytesolution are shown to involve known and accurately tabulated functions. Mayer's infinite series of integrals is summed to give a single integral involving the Debye‐Huckel potential of average force. With the help of the new form, the use of the single cut‐off parameter for binary electrolytes is discussed from a quantitative standpoint.
26(1957); http://dx.doi.org/10.1063/1.1743412View Description Hide Description
It has been found that the van der Waals volume (Rv 3) is directly proportional to the atomic surface area (Rc 2) for electronegative elements. The volumes of the negative ions have also been found to be similarly related to the square of their atomic radii, but the relation is restricted to the same group of the periodic table. The positive ion radii of the alkali and the alkaline earth metals have also been found to be linearly related to their metallic radii.