Volume 16, Issue 9, 01 September 1948
Index of content:
16(1948); http://dx.doi.org/10.1063/1.1747022View Description Hide Description
In this paper we determine the electron distribution, the binding energy, and the ionic radius of the positive ammonium molecule ion. The general idea of our method is that the molecule is divided by a spherical surface which contains the protons and it is supposed, in our first approximation, that the charge of protons is distributed uniformly on this surface. Now, we we have inside our sphere a nitrogen nucleus, the charge of which is over compensated by ten electrons and so a N3− ion is formed. The whole formation can be regarded from the outside of the sphere as similar to the Na+ ion, because the charge of the four protons has been added to the charge of the N nucleus. In a second approximation we pay attention to the fact that the protons are not exactly uniformly distributed on the spherical surface but on the points of a tetrahedron. We have taken into consideration the inhomogeneous field of protons by using the perturbation calculation. The ionic radius of our molecule ion is determined as usual in the statistical theory of atoms. Finally, we check our result with a cycle process. We do not use semi‐empirical parameters.
16(1948); http://dx.doi.org/10.1063/1.1747023View Description Hide Description
In this second part of our paper we have determined the ionization energy of the ammonium molecule and the eigenfrequencies of the positive ammonium molecule ion. Because we know the electron distribution of the positive radical, we can determine the eigenfunction of the valence electron of ammonium in the same way as is done in cases of alkali metals with larger atomic number. In Section I of Part II we review this method. In Section II we determine the eigenfrequencies of the ammonium molecule ion by Neugebauer's method.
16(1948); http://dx.doi.org/10.1063/1.1747024View Description Hide Description
By regarding the two shared electrons of a covalent bond as forming a doubly charged negative ion, and the molecule as consisting of positive and negative ions, one may, in some cases, assign diamagnetic susceptibilities to the constituent parts of the molecule. The values thus found are in good agreement with the experimental results.
16(1948); http://dx.doi.org/10.1063/1.1747025View Description Hide Description
An equation of state for monolayers of large threadlike molecules based on the highly idealized quasi‐lattice model is presented, and applied with fair success to the small number of experimental data available. Although protein molecules in monolayers may be highly organized structures, the theory can be applied to them at moderate filmpressures without requiring unreasonable values for their molecular parameters. By analogy with the three‐dimensional case, the theory requires improvement in order to apply to the low pressure regions, where experimental differences between protein and polymer films should become more marked.
16(1948); http://dx.doi.org/10.1063/1.1747026View Description Hide Description
An experimental procedure is described for measuring dichroism in the infra‐red spectrum of oriented materials. Oriented films of polythene, polyvinyl alcohol, polyvinyl chloride, polyvinyl acetate, and Nylon have been examined in the region 3600–700 cm−1, and the species (parallel or perpendicular) of many bands has been identified. The bearing of these results on current ideas concerning the structure of these polymers is discussed. A general result is that frequencies involving the motion of hydrogen atoms show rather low dichroism. On the other hand, very high dichroism has been found in some frequencies in which the motion is believed to be confined to other atoms.
16(1948); http://dx.doi.org/10.1063/1.1747027View Description Hide Description
The absorption spectra of chlorate, bromate, iodate, and hypobromite ions and of hypobromous acid were measured.
The decomposition of bromate ion was investigated in the light of a mercury arc in the spectral region: 1900A to 2600A. The quantum yield of the decomposition is 0.19. The main decomposition reaction leads to the formation of hypobromite and molecular oxygen. The irradiation of hypobromite ions leads to the formation of bromide and bromate ions in a ratio of about 4 to 1 and to the evolution of oxygen. The decomposition of chlorate ion and iodate ion is analogous to that of bromate. It is assumed that in all these cases the primary process of light absorption consists of the transfer of an electron to the hydration layer. In the case of halate ions, the photo‐chemical reaction can be formulated as a decomposition of the complex (XO3 −·H2O) to XO−+H2O+O2; in the case of the hypobromite, as the decomposition of (XO−·H2O) to X−+H2O+O. In the latter case the oxygen atoms formed are responsible for the formation of bromate.
16(1948); http://dx.doi.org/10.1063/1.1747028View Description Hide Description
The absorptionspectrum of diborane has been investigated in the infra‐red from 1–25μ and in the vacuum ultraviolet down to 1000A. The rotational structure obtained for certain of the infra‐red bands rules out the ethane‐type structure but agrees very well with the interpretation of the electron diffraction results in terms of a bridge model. The ultraviolet spectrum indicates a simple electronic structure and a first ionization potential about 11–12 volts.
16(1948); http://dx.doi.org/10.1063/1.1747029View Description Hide Description
A method is described for isotope enrichment by countercurrent gaseous exchange in a thermal diffusion column. The theory is derived for two cases of interest: diffusion limited and reaction‐rate limited. Solutions of the equations are presented for the over‐all separation S at the steady state as a function of the following: single stage enrichment factor α; diffusion constant D or exchange rate constantk; length of column Z; and the convective flow L, which in turn depends on pressure, temperature, column dimensions, etc. The results may be expressed in the usual form S=α N . For the diffusion‐limited case N=4πDc̄Z/L, where c̄=moles of gas per cc. For the reaction‐rate limited case the number of theoretical plates per unit length is given by the expression N/Z=k/v, where v is the convective velocity.
Experiments are described in which C13 was concentrated by the exchange reaction. The observed dependence of the over‐all separation upon the operational variables is consistent with the theory.
16(1948); http://dx.doi.org/10.1063/1.1747030View Description Hide Description
The mercury photosensitized hydrogenation of propylene has been investigated at 30°, 110°, and 200°, using an 8/1 ratio of hydrogen to propylene. The hydrocarbon products were analyzed with a mass spectrometer. The occurrence of 2,3‐dimethylbutane as the principal C6 product indicates that a hydrogen atom adds preferentially to the terminal carbon atom of propylene to form the isopropyl radical. Analyses of the C6 and C9 products suggests that the isopropyl radical adds preferentially to the middle carbon atom of propylene.
16(1948); http://dx.doi.org/10.1063/1.1747031View Description Hide Description
The magnetic susceptibilities of U(SO4)2·3.26H2O, U(C2O4)2·5H2O and U(C5H7O2)4 have been determined at a series of temperatures from the boiling point of liquid N2 to 60°C. The Weiss‐Curie law is obeyed at temperatures above 195°K. The data indicate the presence of two 5f electrons in the ground state. The susceptibility of Th(C5H7O2)4 at room temperature has also been determined.
16(1948); http://dx.doi.org/10.1063/1.1747032View Description Hide Description
A reinvestigation has been made of the authors' earlier work on the reaction of propylene with mercury (3P1) atoms at 30°C in a static system, with special concentration on the products of the reaction.
The mechanismwhich was proposed in the earlier work has been confirmed. Some twenty‐two different products were identified at low pressures, all of which, with the exception of acetylene, can be explained as the result of interactions of the free radicals present.
The quantum yield of the reaction reaches a maximum of 0.18 at 6.5 mm, and falls to 0.04 at 72 mm.
- LETTER TO THE EDITOR
16(1948); http://dx.doi.org/10.1063/1.1747033View Description Hide Description