Volume 21, Issue 1, 01 January 1953
Index of content:
21(1953); http://dx.doi.org/10.1063/1.1698624View Description Hide Description
A study was made of the effects of gallium impurity on the luminescence emission and trapping in phosphors with oxygen‐dominated host crystals and in phosphors with zinc sulfide host crystal. Gallium acts (1) as an intensifier for host‐crystal emissions in zinc silicate, magnesium silicate, and zinc sulfide phosphors; (2) as an originative activator in zinc germanate phosphor; (3) as a poison for emissions resulting from manganese activator in silicate and germanate phosphors, and for emissions caused by copper and manganese in zinc sulfide phosphors for cathode‐ray excitation; (4) as a sensitizer for emissions resulting from copper and manganese in zinc sulfide phosphors for ultraviolet excitation; (5) as a trapping agent in zinc silicate, magnesium silicate, zinc germanate, and zinc sulfide; (6) as a trapping poison in beryllium silicate phosphors.
Evidence is found for a correlation between types of emission centers and trapping centers in silicate and germanate phosphors.
Results on intensification indicate that intensifier activators are effective in increasing the intensity of host‐crystal emissions by introducing crystal defects of the same type as those formed by random thermal processes in the preparation of the phosphor.
21(1953); http://dx.doi.org/10.1063/1.1698562View Description Hide Description
Apparatus and techniques are described for the sampling of one phase of a liquid‐vapor equilibrium system at high temperatures and pressures. These have been applied to the system NaCl–H2O in the supercritical region. Where the experimental ranges overlap, the present data are in reasonable agreement with that of previous workers. From the data obtained it has been possible to construct partial phase diagrams of the NaCl–H2O system and to calculate partial molal volumes of NaCl. The partial molal volumes of NaCl in steam are the largest partial molal volumes ever reported (order of magnitude of −2 liters) and indicate extensive solvation of the solute molecules in the vapor solution.
21(1953); http://dx.doi.org/10.1063/1.1698599View Description Hide Description
Measurements of dielectric and ultrasonic relaxation in glycerol are compared over a frequency range of 7.5 to 37.5 megacycles and over a temperature range from 20°C to − 25°C. Reduced dielectric and ultrasonic constants when plotted against viscosity at a constant frequency of 30 megacycles appeared quite similar. The imaginary (or loss) part of the reduced constants exhibited a peak at the same viscosity. Both phenomena exhibited a departure from a single relaxation time theory. This deviation of the dielectric phenomena from the simple theory was attributed in the usual manner to a distribution of relaxation times. The striking similarities in the behavior of the dielectric and ultrasonic phenomena suggests an intimate relation between the two. Thus, if a distribution of relaxation times exists for the dielectric, it should in all probability exist in the ultrasonic process.
Both shear and compressional viscous processes are associated with the acoustic phenomena. It was concluded that if any difference exists in the shear and compressional viscousrelaxation times, its effect is masked by a probable distribution in relaxation times for each process.
Calculations indicated that the natural ``rotational jump'' time in glycerol is between ½ and 4 times the ``translational (or viscous) jump'' time.
21(1953); http://dx.doi.org/10.1063/1.1698615View Description Hide Description
Infrared spectra of α‐ and β‐quartz, α‐ and β‐cristobalite, and vitreous silica were studied by the reflection method using natural and polarized radiation in the 700 to 1400 cm−1 wave number interval. By measuring the reflecting powers at two different angles of incidence, the indices of refraction and extinction were obtained and the absorption bands could be correctly located, sometimes at variance with the existing data, based on reflection maxima alone. The strong band at 1055 cm−1 in α‐quartz and at 1095 cm−1 in α‐cristobalite and vitreous silica can be assigned as a valence stretching vibration. Other observed bands are consistent with the already existing assignments. The effect of temperature on the total intensity and width of the bands was studied in a temperature interval between 4°K and 880°K.
Quantitative Studies of Apparent Rotational Temperatures of OH in Emission and Absorption (Spectral Lines with Doppler Contour)21(1953); http://dx.doi.org/10.1063/1.1698618View Description Hide Description
Even if a Boltzmann distribution exists for the population of molecules in various energy levels, it is not possible to obtain a satisfactory interpretation of experimental data by the use of conventional procedures unless the product of maximum spectralabsorption coefficientP max and optical density X is sufficiently small. Detailed calculations are presented which show that the experimental results, which suggest an anomalous rotational temperature for the 2Σ state of OH in low pressure combustionflames, can be accounted for by using sufficiently large values for P max X (Sec. II). Whether or not experimental data should be interpreted in this manner must be determined by auxiliary studies.
Representative absorption studies for the determination of rotational temperatures in isothermal systems have been analyzed for the P 1 branch, (0,0) band, 2Π→2Σ transitions of OH at 3000°K. The calculations show that erroneous interpretation of experimental results occurs if the product P max X is not small compared to unity. Sample calculations for a blackbody light source show that the customary procedure for treating experimental results will permit adequate correlation of the data by straight lines up to relatively large values for P max X. It is remarkable that the preceding statement remains true even under conditions in which emission data clearly indicate that P max X is no longer small compared to unity (Sec. III).
Representative calculations to determine observable peak and total intensity ratios in emission for spectral lines with Doppler contour have been carried out for 2Σ→2Π transitions, (0,0) band, P 1 branch of OH at 3000°K. The calculations show that the ratios of peak and total intensities are functions of the products of maximum absorption coefficients (P max) and optical density (X) for the lines under study (Sec. IV).
Quantitative calculations have been carried out of apparent rotational temperatures in systems containing nonequilibrium distributions of OH at 3000°K and at 6000°K. The calculations on the P 1 branch, 2Σ→2Π transitions, indicate that, in the absence of self‐absorption, conventional plots showing discontinuities necessarily overestimate one and underestimate the other of the known temperatures of 3000°K and 6000°K (Sec. V).
Quantitative calculations on the nature of distortions produced when an isothermal region at 3000°K is viewed through an isothermal region at 1500°K show that the presence of a non‐isothermal field of view magnifies the distortion produced by self‐absorption alone (Sec. VI).
On the basis of the noncontroversial quantitative calculations described in Secs. II to VI for idealized systems, some speculations regarding the significance of reported flame temperature anomalies for OH are presented in Sec. VII.
21(1953); http://dx.doi.org/10.1063/1.1698619View Description Hide Description
Detailed absorption spectra of Am(III), (V), (VI), and Eu(III) in perchloric acid were obtained over the range 200–800 mμ using the Cary Recording Spectrophotometer. Molecular extinction coefficients obtained from the average of several determinations are given for each absorption peak of the americium species. No vibrational fine structure similar to that reported for U(VI), Np(V), Np(VI), and Pu(VI) was found in the visible and ultraviolet spectra of Am(V) and (VI). This fine structure has been interpreted as arising from symmetrical metal‐oxygen vibration in ions of the type MO2 + and MO2 ++.
21(1953); http://dx.doi.org/10.1063/1.1698620View Description Hide Description
The excitation and ionization of the daughter atom coming from a beta‐decay, which is of interest in connection with some hot atom studies and possibly also in connection with beta‐recoil experiments, is the subject of an introductory discussion (Secs. 1, 3, 4, and 5) with explicit calculations given only in the case of one‐electron hydrogenlike wave function representation of atomic states (Sec. 2). The latter correct results in the literature, the only ones so far published on this subject. The present discussion is confined to direct effects of the beta‐process itself and does not evaluate those resulting from Auger processes (Sec. 5).
21(1953); http://dx.doi.org/10.1063/1.1698621View Description Hide Description
Modifications of Ogg's treatment of the electron in a spherical cavity in liquid ammonia lead to a radius of about 4.8A or slightly less, in reasonable agreement with the corrected experimental value of 3.2A. Some specific quantum‐mechanical interactions appear to be necessary in order to make the electron stable.
21(1953); http://dx.doi.org/10.1063/1.1698622View Description Hide Description
The shift with temperature of the absorption edge for β‐Ag2S was measured on a Ag2S ingot and a Ag2S sheet prepared by tarnishing of Ag in sulfur vapor. The measurements indicate a shift in energy of about −1.2 to −1.9×10−3 ev/degree. This value is used to explain the abnormally high value of the numerical factor in front of the exponential term in the expression of conductivityvs temperature. If the change in absorption with temperature is due to the decrease in lattice extension, one should expect a decrease in conductivity with increasing pressure of (1/σ·dσ/dp)∼−0.42/T (T in degrees Kelvin, p in atmospheres). In the course of this study the linear expansion coefficients of β‐Ag2S (15.2×10−6 per degree) and of α‐Ag2S (37.5×10−6 per degree) have been measured.
21(1953); http://dx.doi.org/10.1063/1.1698623View Description Hide Description
Dispersion due to water vapor in the wavelength region ∞ to 0.6 mm is computed by means of quantum‐mechanical formulas. The dispersion is attributed to: (1) The contributions of the 11 rotational lines in the region considered; these are obtained with a dispersion equation characteristic of collision theory specialized to sharp lines. (2) The combined contribution of all rotational lines of shorter resonance wavelength. This is obtained with the aid of the well‐known shape factor (ν n 2—ν2)−1, which is shown to be valid for sharp lines independent of any special model.
The strongest line, 31−4−3, occurs at 0.794 mm, and it gives rise to a maximum change in susceptibility ε′−1 of 8.2×10−6 for 1 atmos of air containing 1 percent water molecules. The increase in ε′−1 from ∞ to 0.6 mm is about twice this value. If the very small effect of the 1.35‐cm line is neglected, a simple equation for ε′−1 holds from ∞ to 2 mm.
21(1953); http://dx.doi.org/10.1063/1.1698625View Description Hide Description
The intramolecular isotope effects in the decarboxylation of C13 and C14 carboxyl‐labeled malonic and bromomalonic acids have been determined. The observed C13 effects are in agreement with the results of other investigators; the C14 effects are in partial agreement with earlier published results of one of the authors. The ratio of C14 to C13 effects is found to be near 3.6.
21(1953); http://dx.doi.org/10.1063/1.1698626View Description Hide Description
The intense so‐called ``intermolecular charge‐transfer spectra'' shown by a large number of molecular complexes in solution are found to exhibit certain regularities in regard to wavelength and intensity. The wavelengths of these transitions show an excellent correlation with the ionization potentials of the electron donor partners of the complexes. The intensities of the charge‐transfer transitions are markedly dependent on the electron acceptor partner of the complex. These results are examined in terms of possible theoretical interpretations of the charge‐transfer transitions.
21(1953); http://dx.doi.org/10.1063/1.1698627View Description Hide Description
Equilibrium in the reaction NH3(g) +HD(g)=NH2D(g)+ H2(g) was measured in the temperature range 210°K to 295°K. The results may be expressed by the relation K=0.972 exp 509/T. The zero‐point energy difference between NH3 and NH2D is calculated to be 635±3 cm−1.
21(1953); http://dx.doi.org/10.1063/1.1698628View Description Hide Description
The current emerging from single molecules of zinc phthalocyanine in field emission has been measured as a function of voltage. The data permit estimation of the ionization potential at ca 7 volts. Comparison of the experiments with a simple theory based on the emission of electrons from the molecule itself supports this view of image formation. It is shown that the images found are not diffraction patterns, but the result of electronoptical effects. Emission measurements on molecules adsorbed on clean tungsten substrates show that irregularities of 5–10A exist on the best and cleanest of these surfaces.
21(1953); http://dx.doi.org/10.1063/1.1698629View Description Hide Description
The optical absorption of sulfur has been studied in the vapor and liquid state and in solution. These measurements indicate the presence of S8 ring molecules which disappear at high temperature. The absorption edge in the liquid shifts at the rate of 6.20A/°C toward longer wavelengths with increasing temperature. It is believed that this displacement is related to the thermal excitation of the vibration levels of the sulfur molecules.
21(1953); http://dx.doi.org/10.1063/1.1698630View Description Hide Description
Theories of the origin of interactions in the vibrational potential function are briefly discussed. It is concluded that the present accepted theory, based on the assumption of orbital hybridization changes, and van der Waals forces between nonbonded atoms, is in need of some modification. Consistent results are obtained if the orbital amplitude, directly relatable to the valence angle, is employed as the parameter deciding signs of interactions, the determining factor then being the energy increment in the system of oscillating bonds, relative to the increment without change of amplitude. This puts the orbital valence theory of dynamic interactions on a more fundamental basis.
21(1953); http://dx.doi.org/10.1063/1.1698631View Description Hide Description
The Matano‐Boltzmann method of graphical calculation of diffusion coefficients in solutions is replaced by an analytical method in certain systems. This procedure enables accurate calculation of diffusion coefficients near the concentration extremes. An equation is derived for the diffusion coefficient D as a function of concentration c. The equation predicts a variation of D with c which is not exponential in metallic systems, contrary to the proposal of Wagner. Comparison of D values with those obtained graphically, for the system copper‐nickel, indicates that the graphical values may be appreciably in error at that extreme where the diffusion coefficient is greatest.
Raman and Infrared Spectral Data, Assignments, Potential Constants, and Calculated Thermodynamic Properties for Oxalyl Chloride21(1953); http://dx.doi.org/10.1063/1.1698632View Description Hide Description
Raman displacements, semiquantitative relative intensities, quantitative depolarization factors (single‐exposure method), and infrared wave numbers have been obtained for liquid oxalyl chloride (ClOC–COCl) at room temperature. A critical examination of the present and previous data has been made and probable values have been determined. Normal coordinate treatments have been made for both the cis‐ and trans‐forms. A satisfactory assignment of the present and previous Raman and infrared bands has been made, assuming the sample to be in the trans‐form. Only binary combinations and 1st overtones were used, except for the 2 highest bands at 3740 and 5140 cm−1. Fermi resonance occurs in 4 cases. Not more than 10 percent of the cis‐form can be present, and the presence of even this much rests solely upon Saksena and Kagarise's reported temperature variation in the intensity of the 533‐cm−1 Raman band, though the normal coordinate treatment does indicate that the strongest trans‐Raman line at 620‐cm−1 could occur near 533 for the cis‐structure. The moderately polarized resonance triplet 450, 471, 488 can hardly be accounted for by the presence of a polarized fundamental in this region, for either the cis‐ or the trans‐form. The heat content, free energy,entropy, and heat capacity were calculated (rigid rotator, harmonic oscillator approximation) for 11 temperatures from 100° to 1000°K for the ideal gaseous state at 1 atmos pressure.