Volume 14, Issue 11, 01 November 1946
Index of content:
14(1946); http://dx.doi.org/10.1063/1.1724080View Description Hide Description
By combining the gas‐metal equilibrium data available in literature and the thermodynamic quantities of gaseous molecules and atoms from the method of statistical mechanics,thermodynamic constants for the solution processes of some atoms in some metallic solvents have been obtained.
14(1946); http://dx.doi.org/10.1063/1.1724081View Description Hide Description
The application of punched cards and electrical accounting machines (of the International Business Machines Corporation) to crystal structure calculations is described. The machines may be used to evaluate Fourier series with greater accuracy, greater speed, and greater density of calculated points than is possible by the methods used heretofore. A method for the punched‐card calculation of structure factors is also set forth, and the use of the machines for the reduction of observational equations to normal equations in least squares is discussed.
The Use of Punched Cards in Molecular Structure Determinations II. Electron Diffraction Calculations14(1946); http://dx.doi.org/10.1063/1.1724082View Description Hide Description
Special files of punched cards for use with the electrical accounting machines of the International Business Machines Corporation in evaluating the Fourier sums and integrals used in the determination of the structure of gas molecules from electron diffraction photographs are described.
14(1946); http://dx.doi.org/10.1063/1.1724083View Description Hide Description
The rotational structure of several violet absorption bands of ClO2 has been studied. The bands considered correspond to the vibration transitions (v 1′ 0 0)←(0 0 0) where v 1′ = 1, 2, 3, 4, and 5. The most prominent identifiable feature of the rotational structure is a doublet qQ branch resolved in the tail of each band. For v 1′ = 1, 2, and 3, the rotational wave numbers of these branches are given byThis fits the spectrum in the observed range of quantum numbers, K = 11 to 20 and L = K to K+8. The first two terms are associated with that prolate symmetrical top which comes closest to the actual ClO2 molecule. Hence, neglecting the effect of asymmetry on the spectrum,andThe last term is associated with spin doubling. The coupling is shown to be close to Hund's ``case b.'' The linear terms in L and K may be a consequence of the doubling. The term in v 1′K describes an outstanding feature of the spectrum but is not interpreted. The bands are shown to be of the parallel type. A few qP and qR branches have also been identified and Δ1 F values have been found. Assuming the spectrum to be that of a prolate symmetrical top, the resulting values of 2B̄ for the vibrationless states are 2B̄″ = 0.612 cm−1 and 2B̄′ = 0.550 cm−1. The value of 2B̄″ with the Cl–O distance s″ = 1.53A from electron diffraction is sufficient to determine the lower electronic state. The upper state is then determined from the values of 2ΔB̄ and 2(ΔA — ΔB̄) for the vibrationless states. The resulting model of both states is designated as model (2). Error in this model, because of the fact that the effect of asymmetry was neglected, is found to be small. Asymmetry correction made on model (2) leads to the following model:The rotational isotope effect is observed and explained but gives no additional information about the molecular model.
14(1946); http://dx.doi.org/10.1063/1.1724084View Description Hide Description
14(1946); http://dx.doi.org/10.1063/1.1724085View Description Hide Description
The theory of scattering by an inhomogeneous dielectric medium has been extended so as to account for the turbidimetric behavior of polymer solutions in solvent‐precipitant mixtures. It is predicted by this theory and verified by experiment that correct values of molecular weight are obtained by the usual interpretation of turbidity measurements if and only if the solvent and precipitant have the same refractive index. The practical utility of turbidimetry in high polymer solutions is shown to be greatly increased by the proper use of solvent‐precipitant mixtures. If the solvent and precipitant have different refractive indices,scattering measurements give information about the extent of selective absorption of solvent by the polymer.
- LETTERS TO THE EDITOR