Index of content:
Volume 8, Issue 10, 01 October 1940
The Infra‐Red Absorption of Phenol and Its Halogen Derivatives in the Region of the Second Overtone of the OH Absorption8(1940); http://dx.doi.org/10.1063/1.1750575View Description Hide Description
Orthohalogen and symmetrically trihalogen substituted phenols in the region of the second overtone of the OH absorption show behavior that is similar to that in the region of the first overtone but with increased displacement of the component absorptions. Subsidiary peaks are observed in the region of the second overtone and appear to stand in ordered relation to the principal peaks. In the present work the ortho‐ and symmetrically trichloro‐, bromo‐, and iodophenols as well as pentachlorophenol and phenol itself have been studied in carbon tetrachloride solution. The tendency of phenol to associate in a series of polymers has been studied by means of the phenol absorption. Relative to phenol the association of the above‐mentioned substituted phenols is small.
Combination Frequencies Associated with the First and Second Overtone and Fundamental OH Absorption in Phenol and Its Halogen Derivatives8(1940); http://dx.doi.org/10.1063/1.1750576View Description Hide Description
Absorption maxima occurring in the near infra‐red spectra of phenol and seven of its halogen derivatives have been measured and interpreted as combination frequencies in which the valence vibration of the OH group combines with frequencies of the body of the molecule. Certain of these absorptions underlie some of the trans‐peaks of the orthohalogen phenols causing such a trans‐peak to appear of larger area than that due to the trans‐peak alone. A group of the combination frequencies which lie in the range 1000–1600 cm—1 above the first overtone OH absorption have been observed as a group of an order of magnitude weaker intensity in the frequency range twice the values above the first overtone OH and also above the fundamental OH absorption, apparently involving two units of vibration in the combining frequencies. A close correspondence is found between the frequencies involved in these combination tones and the frequencies which have been observed in some of these compounds in the deep infra‐red and in Raman spectra.
8(1940); http://dx.doi.org/10.1063/1.1750577View Description Hide Description
A system of eight discrete and several diffuse bands in the ultraviolet absorptionspectrum of NO2 has been analyzed. From the positions of the bands and their temperature coefficient of absorption the upper state intervals have been determined as 523 and 714 cm—1, those of the lower state as 749 and 1319 cm—1. The latter are not the same as the fundamentals deduced from infra‐red data. Different possibilities of reconciling these intervals are discussed.
8(1940); http://dx.doi.org/10.1063/1.1750578View Description Hide Description
The rotational structure of the 2491A band in the ultraviolet absorptionspectrum of NO2 is not completely resolved, but the spectroscopic constants have been determined from the spacing of the subbands (groups of transitions with the same K), their intensity, the temperature coefficients of absorption and finally from the comparison of synthetic spectra constructed from arbitrary constants with the observed spectra. The O–N–O angle in the lower state is 154° and the N–O distance is 1.28A. For the excited state the angle remains essentially the same, the internuclear distance increasing to 1.41A.
8(1940); http://dx.doi.org/10.1063/1.1750579View Description Hide Description
The absorption spectra of gaseous methylamine and dimethylamine have been measured in the region from 6000 to 12,000A using a 105‐foot stainless steel absorption tube and a 3‐m gratingspectrograph. Absorption bands were observed at 7940, 9100, 9940, 10,070, 10,330 and 11,800A in methylamine and at 7940, 8045, 9100, 10,360, 10,625 and 11,800A in dimethylamine. The only band showing resolvable fine structure was that at 9940A in methylamine. Wherever possible the observed bands have been assigned to overtones and combinations of the fundamental N–H and C–H valence vibrations.
8(1940); http://dx.doi.org/10.1063/1.1750581View Description Hide Description
The energy levels for the configuration d 3 of the chrome ion in chrome alum are calculated by starting with the empirical spectroscopic data on the free Cr+++ ion, and then making the assumption that the interatomic forces in the solid state can be represented by a crystalline potential of cubic symmetry, whose magnitude is taken from Schlapp and Penney's theory of the magnetic susceptibility. The particular point to be tested is whether in the solid there is a doublet level only 15,000 cm—1 above the basic quartet state, as predicted in the preceding paper from the study of Spedding and Nutting's data on the Zeeman effect. The computed deepest doublet is about 18,200 cm—1 higher than the ground level, but the discrepancy is not excessive in view of uncertainties in the parameters of the crystalline field and the fact that any ``one‐atom'' model is only an approximation in the solid state. As already suggested by Spedding and Nutting, it is very essential in computing the positions of excited levels, to include elements of the crystalline potential which are nondiagonal in the quantum number L, for without them the lowest doublet is much too high, viz. 30,000 cm—1 above the ground term. On the other hand, the effect of these nondiagonal members is shown to be unimportant for the ground level of greatest multiplicity, not merely for Cr+++ but also for other salts of the iron group, so that previous calculations by various writers on magnetic susceptibilities are not appreciably impaired by their assumption of Russell‐Saunders coupling.
8(1940); http://dx.doi.org/10.1063/1.1750582View Description Hide Description
The fine structure of the parallel‐type band due to the C–H stretching vibration of ethylene has been obtained with a 7500‐line grating. From the measured wave numbers of the lines of this band the mean of the two large moments of inertia of C2H4 has been determined as 30.08×10—40 g cm2. This value combined with the value C=5.70×10—40 g cm2 for the small moment gives for the large moments of inertia A=33.20×10—40 g cm2 and B=27.50×10—40 g cm2. These values are in good agreement with those previously reported.
8(1940); http://dx.doi.org/10.1063/1.1750583View Description Hide Description
The mercury photosensitized decomposition of ethane has been investigated at temperatures up to 475°C. It is found that the products of the reaction are very similar to those at low temperatures. It is concluded that the primary step is a C–H bond split, and that the most important secondary reactions areThe quantum yield approximately doubles on going from 100° to 475°C. No evidence of chain characteristics is found up to 475°C, and it is concluded that the mechanism of the reaction at high temperatures does not differ essentially from that at low temperatures.
8(1940); http://dx.doi.org/10.1063/1.1750584View Description Hide Description
The mean lifetime of the fluorescence of diacetyl vapor has been determined by direct measurement with a phosphoroscope to be 1.65 × 10—3 sec. Quantitative measurement of the diffusion of the excited molecules from a beam of exciting illumination, at different pressures, has also been made and the results are compatible with this lifetime. Integration of the absorption coefficient over the band associated with the fluorescence leads, on the other hand, to a lifetime of the excited state of 10—5 sec. To explain this discrepancy and other facts known about the fluorescence various mechanisms are considered, of which the most satisfactory seems to be this: Following light absorption, X→A, the diacetyl molecule goes without radiation into a long‐lived state M, lying near A.Fluorescence occurs only upon return to A. M may correspond to a tautomeric rearrangement of the molecule. Acetone, radiated with λ3130, shows fluorescence identical with that of diacetyl radiated with λ4358, but the fluorescence grows with time. It can be produced immediately with high intensity by adding diacetyl. The growth curve has been determined and is of form, It = I 0 (1 — e—kt ). Diffusion experiments show the lifetime of the fluorescence in acetone to be equal to that in diacetyl and that the lifetime, or rate of decay, is independent of exciting intensity. The conclusion is that the same molecule, presumably diacetyl, is responsible for the fluorescence in both cases. Possible mechanisms for the excitation of diacetyl in acetone are discussed.
8(1940); http://dx.doi.org/10.1063/1.1750585View Description Hide Description
The problem of simultaneous conduction and diffusion through a constrained diffusion layer is discussed. An exact solution is obtained for the case of an ideal dilute solution containing only two ionic species. The special case of divalent ions diffusion into a uni‐divalent electrolyte is also solved by numerical methods. It is shown that for diffusion layers of thicknesses of the order of 50μ the potential drop across the layer for currents of the order of magnitude of 100 milliamperes per sq. cm is less than one millivolt. It is therefore legitimate to neglect the diffusion potential in comparison with the double layer potential at an electrodesurface.
The Rate of Solution of Metals in Acids as a Function of Overvoltage II. The Solution of Cadmium in Sulfuric Acid8(1940); http://dx.doi.org/10.1063/1.1750586View Description Hide Description
The rate of solution of cadmium in sulfuric acid has been measured as a function of the hydrogen overvoltage at the electrode surface. The rate was found to be constant at a given potential, independent of the concentration of sulfuric acid used. The rate increases with the electrode potential in accordance with the theory of Kimball. From the dependence of the rate on the speed of stirring, and also from the behavior on varying the potential, it is concluded that the solution process is diffusioncontrolled. The effect of surface inhomogeneities was too great to permit an evaluation of the absolute rate.
Solvent Action on Optical Rotatory Power III. The Influence of Liquid Structure on the Interaction of Dipoles8(1940); http://dx.doi.org/10.1063/1.1750587View Description Hide Description
By taking into account the London ``dispersion'' forces and the structural characteristics of a liquid system, an equation for the change of rotivity per mole of dipole solvent in unit volume for liquid solutions is obtained which has the same form as the equation obtained by Beckmann and Cohen for a mixture of gases that are perfect except for dipole interaction, namely,This is due to the fact that the polarization term arises from the integration over the angles of orientation alone. The constants, G(α, β, γ) and K γ have, of course, a new significance in the present work.
Solvent Action on Optical Rotatory Power IV. The Rotivity of Dipropionyl‐Diethyl‐d‐Tartrate and l‐Menthyl Acetate in Aromatic and Aliphatic Solvents8(1940); http://dx.doi.org/10.1063/1.1750588View Description Hide Description
Experimental data are presented to demonstrate the validity of the equations of Beckmann and Cohen and Beckmann and Marks for the change of rotivity with solvent. Mixtures of polar and nonpolar solvents of both aromatic and aliphatic types were used with dipropionyl‐diethyl‐d‐tartrate and l‐menthyl acetate as optically active substances. The data are discussed in terms of the theory and essential agreement is found in all cases over a wide range of concentrations.
8(1940); http://dx.doi.org/10.1063/1.1750589View Description Hide Description
Because vibrations have been found in liquids which closely resemble what have been regarded as lattice vibrations in crystals, we examine whether the vibrations in crystals are to be ascribed to local complexes rather than to an extended lattice. Our experiments confirm the appropriateness of the term ``lattice vibrations'' and analogous vibrations must, it seems, be accepted as taking place in solutions. Alcohol with a more regular arrangement within the liquid than water gives rise to greater sharpness in the quasi-lattice vibrations of the solution. Correspondingly, a mixed solvent gives a greater spread and diffuseness to the vibrations even though the electric fields immediately surrounding the positive ions in such a solution are as sharp in their effect on the electronic levels as in the pure solvents separately. With absolute alcohol, europium chloride and europium nitrate form solutions which show different quasi-lattice vibrations in their spectra; but when these salts are dissolved in water, the vibrations of the solutions appear about the same. The hydrated crystals of europium chloride exhibit lattice vibrations which are different from those of the hydrated mixed magnesiumeuropium nitrate. In the ionic crystals of anhydrous europium fluoride, a lattice frequency appears; this is considerably greater than any yet measured. A discussion concerning the nature of the systems partaking in the quasi-lattice vibrations is included.