Volume 11, Issue 6, 01 June 1943
Index of content:
11(1943); http://dx.doi.org/10.1063/1.1723837View Description Hide Description
The infra‐red absorption spectrum from 2 to 14.5μ was determined for cyclohexane vapor. The number of bands found in the 700–1350 cm−1 region confirms the chair structure (symmetry D 3d ) as the most stable at room temperature. The band envelopes are discussed and compare well with the theory of Gerhard and Dennison.
Determination of Chlorine Vibrations in Dichlorobenzenes from Intensities and Polarizations of Their Raman Lines11(1943); http://dx.doi.org/10.1063/1.1723838View Description Hide Description
Intensities and polarization properties of vibrations in which mainly chlorine atoms are participating, are investigated theoretically for the dichlorobenzenes. It is assumed that the change of polarizability in these vibrations is connected primarily with displacements of the chlorine atoms and that contributions from the individual atoms are additive. The Raman tensors belonging to the chlorine vibrations are then obtained by either adding or subtracting the single C–Cl contributions with reference to a chosen system of axes rigidly connected with the molecule. Intensity ratios were obtained for the symmetrical and unsymmetrical valence vibrations and deformation vibrations, respectively. Very small depolarization factors were found for lines representing symmetrical valence vibrations. For deformation vibrations the simplified theory gives complete depolarization for all allowed Raman lines. The results are discussed in connection with existing experimental data.
Optical Sensitizing of Silver Halides by Dyes IV. The Optical Sensitizing Properties of Fluorescein Dyes in Relation to Their Spectral Absorption and Constitution11(1943); http://dx.doi.org/10.1063/1.1723839View Description Hide Description
A comparison of increasingly halogenated fluoresceins shows that, with increasing weight of halogen introduced, the principal visible absorption moves steadily to longer waves, as also the first ultraviolet band. At the same time the acid dissociation constants of the phenolic and carboxylic groups tend to become indistinguishable, while the solubilities of the silver compounds decline. The various structures involved in the resonance of the alkaline, hydrogen, and silver compounds are discussed. Measurements of the solubility of silver erythrosinate show this to vary with ``aging'' and particle size. The solubility of silver erythrosinate on adsorption to silver bromide is apparently lower than that of the pure compound. The adsorption is oriented, an edge‐on or end‐on monolayer being formed. Although not irreversible, there is a peculiar deviation from the Langmuir isotherm. The optical sensitizing appears to occur by a mechanism similar to that with basic dyes. Initially, transfer of an exciton to the silver halide seems indicated, rather than of an electron.
11(1943); http://dx.doi.org/10.1063/1.1723840View Description Hide Description
The activated complex theory of reaction rates is discussed critically. The transmission coefficients for a number of idealized energy surfaces have been computed quantum mechanically. It appears that curvature of the reaction path may introduce activation energy in addition to that caused by constriction and elevation of the energy valley. Except at low temperatures, this additional activation energy is almost negligible. However, it may contribute to the separation of isotopes, where small differences in activation energy are important. For systems in thermal equilibrium at room temperatures and above, the average quantum mechanical transmission coefficient is found to differ insignificantly from that calculated by classical mechanics.
11(1943); http://dx.doi.org/10.1063/1.1723842View Description Hide Description
By making use of Polya's theorem and the groups of symmetries of the geometrical models representing unsubstituted parent compounds, it is possible to include the various kinds of isomerism in a single discussion. The number of isomers calculated by this procedure is the total number of all types.
11(1943); http://dx.doi.org/10.1063/1.1723844View Description Hide Description