bluuebunny/crossref_metadata_2025 huggingface dataset:
Mass Spectrometric Study of the Kinetics of Nitrogen Afterglow
Authors: Berkowitz Joseph , Chupka William A. , Kistiakowsky G. B.
Published: January 2005

Lewis-Rayleigh afterglow in nitrogen has been examined by simultaneous observation with a mass spectrometer and a photomultiplier. Afterglow intensity was found to be proportional to the square of the ground-state nitrogen atom concentration under a variety of conditions. The proportionality constant was essentially unaffected by small oxygen addition, but was somewhat increased with admixture of noble gases. Evidence is presented for a linear dependence of afterglow intensity on total pressure of nitrogen. Addition of nitric oxide to the afterglow results primarily in the production of nitrous oxide. From a rough calibration of the atomic concentration (ca 1%) and the afterglow radiation intensity, (1013 photons/cc-sec) a termolecular rate constant of 2×10—33 cc2-molecule—2-sec—1 is obtained.

The experimental data point to a termolecular reaction involving two 4S nitrogen atoms. The detailed mechanism probably involves the intermediate formation of the 5Σg+ molecular state, followed by a collision-induced, radiationless transition into the 3πg state.
Successive Neutron Capture in Tb159
Authors: Smith R. R. , Reeder S. D. , Lewis R. H.
Published: January 2005

The presence of a 6.8-day activity having a chemical nature similar to or identical with that of terbium has been observed in a sample of Tb4O7 irradiated in a high neutron flux in the Materials Testing Reactor. This activity is believed to be that of Tb161 formed by secondary neutron capture in Tb159. Measurements of the relative beta intensities of the first and second order species have been made and lead to a value of 525±100 barns for the pile neutron absorption cross section of Tb160.
Low-Frequency Librations and the Vibrational Spectra of Molecular Crystals
Authors: Hexter R. M. , Dows D. A.
Published: January 2005

The effect of librations of molecules about axes perpendicular to those of the transition moments of molecular vibrations upon the dichroic ratios associated with such vibrations in the infrared spectra of molecular crystals is considered. It is demonstrated that if such librations are harmonic and of small amplitude, the root-mean-square deviation of the molecular orientation from its equilibrium orientation is sufficient to account for the deviation of observed dichroic ratios from those predicted by the ``oriented gas model.'' Deviations of this type previously reported from the polarized infrared spectra of iodoform, brucite, para-dichloro-benzene and benzene are reviewed. From a knowledge of the libration frequencies determined by examination of infrared or Raman spectra of molecular crystals, and of the observed dichroic ratios of polarized infrared spectra, the orientations of molecules and/or functional groups of molecules in crystals may be quantitatively determined. It is also demonstrated that as a consequence of the model used for correction of observed dichroic ratios, a branch-type libration-vibration spectrum of such crystals is predicted. The fine structure of this spectrum is discussed and is shown to be similar, in many ways, to the rotation-vibration spectra of polyatomic gases.

The relationship of this work to the interpretation of electron density maps of molecular crystals is discussed.
Evaluation of Molecular Quadrupole Moments from Microwave Spectral Line Breadths. I. Theoretical
Authors: Smith William V.
Published: January 2005

The breadths of microwave spectral lines in gas mixtures may arise from several different interactions. It is shown that when the radiating molecule is the linear molecule OCS, polarizability interactions predominate, but when the radiating molecule is NH3 undergoing inversion, quadrupole moment interactions predominate. Consequently, NH3 is a particularly suitable molecule to use as a ``probe'' to measure quadrupole moments of other molecules. An improved theoretical analysis leads to a revision of previously published molecular quadrupole moments.
General Formulas for Kinetic Energy Matrix Elements of In-Plane Vibration in Planar Molecules
Authors: Shimanouchi Takehiko
Published: January 2005

General formulas for kinetic energy matrix elements are given in terms of internal coordinates of the bond stretching and bending type for in-plane vibration in planar molecules. The definition for the sign of bond angle makes those formulas independent of the mutual positions of atoms. An example is given.
Theory of Dilute High-Polymer Solutions (the Pearl Necklace Model)
Authors: Isihara A. , Koyama R.
Published: January 2005

A theoretical expression for the second virial coefficient A2 of chain polymer solutions is derived. This accounts for the empirical relation between A2 and molecular weight M, according to which A2 is proportional to M—α. α has a value of about 0.23 over a suitable range of molecular weight. According to the theory, α≈½—¾· (log1.684x), when x, a variable proportional to the square root of M, becomes very large. The temperature variation of A2 is also explained. Krigbaum and Flory's data on the molecular weight and temperature dependence of A2 are discussed.
NH2 Deformation Frequencies of Inorganic Coordination Complexes
Authors: Mizushima San-ichiro , Nakagawa Ichiro , Sweeny D. M.
Published: January 2005

The normal vibrations of the infinite chain of the (HgNH2)+ ion has been calculated on the basis of the Urey-Bradley field. The calculated values have been found to be in good agreement with those observed in the infrared spectra of HgNH2Cl.
One-Dimensional Inviscid Flow through a Rocket Nozzle
Authors: Rastogi R. P. , Pandya T. P.
Published: January 2005

A thermodynamic theory of one-dimensional nonisentropic flow through a rocket nozzle is developed by using a parameter called ``extent of reaction'' introduced by de Donder. The formalism makes it possible to compute the exhaust velocity and cooling rate when there are significant departures from chemical as well as internal equilibrium.

It is shown that the cooling rate at the throat is likely to increase when the departures from equilibrium become significant.
Electric Strength of Saturated Hydrocarbon Gases
Authors: Devins J. C. , Crowe R. W.
Published: January 2005

An attempt has been made to correlate the sparking potentials of nonattaching polyatomic gases with molecular structure. The investigation has included the normal alkanes containing from one to six carbon atoms, their branched chain isomers, cyclopentane, and cyclohexane. For a given electrode separation and pressure, the electric strengths of the normal alkanes increase with increasing chain length. Using a Townsend-like criterion for breakdown it has been possible, with certain assumptions, to calculate from the measurements relative cross sections for electron scattering by these molecules. This scattering cross section is proportional to the number of carbon-hydrogen bonds in the molecule, and independent of the number of carbon-carbon bonds. It is independent of molecular shape, i.e., of branching or cyclization.
Optimum Atomic Shape for Bertaut Series
Authors: Jones Robert E. , Templeton David H.
Published: January 2005

Calculations are made of the error in the Madelung constant when computed by Bertaut's method with a finite number of terms and with various shapes for the charge distribution within the atoms. A charge density which is proportional to the distance from the edge of the spherical atom gives most rapid convergence for the range of accuracy one percent to 0.003 percent. For higher accuracy a better shape is charge density proportional to the square of the distance from the edge. If Gaussian atoms are used and overlap neglected, no choice of parameter allows an accuracy for a given number of terms as great as for the above functions. If the overlap effect is included by a second series (double series of Ewald), the convergence can be made more rapid than for any of the single series methods, but at the price of a more complicated program.
Adsorption of Oxygen on Zinc Oxide
Authors: Morrison S. R. , Miller P. H.
Published: January 2005

In studies of the electrical characteristics of zinc oxide, reported elsewhere, it was suggested that adsorbed oxygen plays an important role in determining the electrical conductivity of the material. Further studies of the photoconductivity by Melnick have also indicated the presence of adsorbed oxygen on zinc oxide. As a check that the interpretation of the electrical characteristics is reasonable, we have made some rough volumetric measurements of the adsorption of oxygen. We are publishing the results of these measurements in hope that they will inspire a more detailed study of this interesting problem than we have been able to provide.
Molecular Screening Constants
Authors: Musulin Boris
Published: January 2005

An empirical method is suggested for the calculation of molecular screening constants. The method is based upon the values of the screening parameter in atomic orbitals. Comparisons are made with some variational calculations.
Microwave Spectra of Thiophene, 2- and 3-Monodeutero, 3,3′-Dideutero, and Tetradeuterothiophene. Structure of the Thiophene Molecule
Authors: Bak Bo/rge , Christensen Daniel , Rastrup-Andersen John , Tannenbaum Eileen
Published: January 2005

2- and 3-monodeutero, 3,3′-dideutero, and tetradeuterothiophene have been prepared and their microwave spectra recorded together with the microwave spectrum of ordinary thiophene (C4H4S). Lines originating from the 4% content of C4H4S34 and the 2% content of C3C13H4S in ordinary thiophene (both the 2- and the 3-C13 species) were also identified. For all isotopic species rotational constants of high accuracy were obtained. The total material is sufficient for a complete determination of all the 8 geometrical parameters of thiophene.
Anisotropic Color Centers in α Quartz. Part I. Smoky Quartz
Authors: Cohen Alvin J.
Published: January 2005

The color center at 460 mμ produced by x-irradiation of naturally colorless or bleached smoky quartz is anisotropic. The absorption maximum of this color center for the extraordinary ray is 460 mμ and for the ordinary ray is 485 mμ. A second anisotropic peak with maximum in the vicinity of 625 mμ for the extraordinary ray is also present. The relative anisotropy of these color centers in a natural, a Bell synthetic and a Brush synthetic quartz are compared and found to be nearly identical in the case of the synthetic quartzes studied. The absorption coefficients of these color centers x-rayed to saturation are compared with total aluminum content for five specimens.
Mass Spectrometric Study of Phase Changes in Aluminum, Praseodymium, and Neodymium
Authors: Johnson Robert G. , Hudson Donald E. , Caldwell Wallace C. , Spedding Frank H. , Savage William R.
Published: January 2005

A sensitive method has been developed for measuring rapidly the latent heat of vaporization or sublimation of metals of low volatility. Atoms from the saturated vapor emerge from a small Knudsen-type effusion cell and impinge upon a hot filament. A fraction of the incident atoms re-evaporate from the filament as ions and are detected by a mass spectrometer. The Clausius-Clapeyron equation is used to obtain the latent heat from the dependence of ion current upon cell temperature. Application has been made to aluminum, praseodymium, and neodymium. The work on aluminum yielded an enthalpy of sublimation at 298°K of 78.0±0.4 kcal/M. Some anomalous behavior was observed in the rare earths. Preliminary molar enthalpy values are: Pr, 79.3±2.0 kcal (vaporization at 1380°K); Nd, 70.6±2.0 kcal (vaporization at 1348°K) and 74.1±2.0 kcal (sublimation at 1236°K). An estimate of the heat of fusion of Nd yielded 3.5±1.0 kcal/M.

The method also provided a convenient measurement of first-order phase transition temperatures. The melting points of Pr and Nd were found to be 1192±2°K and 1292±2°K respectively. In addition, a solid-to-solid phase transition was found in Nd at 1142±2°K.
Crystal Structure of Barium and Europium at 293, 78, and 5°K
Authors: Barrett C. S.
Published: January 2005

Reasons are reviewed for suspecting that it may be possible to induce phase transformations in barium and europium. X-ray diffraction patterns at 78°K and 5°K, however, revealed no transformation from the normal body-centered cubic structure; there was none, also, after cold work at 5°K. The lattice constants at 5°K are 4.551±0.003 A for europium, 5.000±0.002 A for barium.
Modification of the Vector Model to Include a First-Order Nonorthogonality Correction
Authors: Simpson William T.
Published: January 2005

When the vector model is used to describe chemical bonding it appears that the orbitals participating in bond formation are required to be orthogonal. The success of the model on an empirical basis is puzzling because chemical bonding will not occur without overlap. In the present work the many-electron functions, consisting of products of appropriately overlapping ordinary atomic orbitals, are orthogonalized. The characteristic simple form of the model is then retained provided that the exchange integral is replaced by a corrected exchange integral called a bond integral. The success of the model becomes less puzzling because this integral is usually evaluated empirically. The nature of the bond integral is examined in the framework of the Heitler-London treatment of the hydrogen molecule.
Delta-Potential Function Model. II. Aromatic Hydrocarbons
Authors: Frost Arthur A. , Leland Frances E.
Published: January 2005

The pi electrons are considered as following a one-dimensional network through the molecule as in the free electron model. The potential energy is taken as zero everywhere except at each pi-carbon nucleus where it goes to minus infinity as a negative delta function. By a procedure of linear combination of atomic orbitals, suitably defined, exact solutions of the Schrödinger equation are easily obtained. Negative one-electron energy levels, of which there may be as many as there are pi-carbon nuclei, are interpreted as bound states, with energy zero or positive as ionized states.

This model stands between the free electron model on the one hand and the LCAO molecular orbital model on the other. It goes beyond the former in that it can predict not only excitation energies and resonance energies, but also ionization potentials. It surpasses the latter in that exact solutions are obtainable. Numerical results are qualitatively of the right order of magnitude after adjustment of the strength of the delta function which is the one and only variable parameter.
Isothermal Calorimeter and the Heat of Mixing of Iso-Octane-Perfluoroheptane Solutions
Authors: Mueller Charles R. , Lewis James E.
Published: January 2005

An isothermal calorimeter for measuring heats of mixing of binary solutions has been designed. The instrument utilizes twin calorimeters to eliminate troublesome corrections and a pair of differential thermistors for controlling the electrical circuit. There is no vapor space and the rate of mixing is controlled so that the heat absorbed is automatically compensated and the maximum temperature change is of the order of 0.001° to 0.002°C. This is accomplished by a differential bridge.

The heats of mixing of perfluoroheptane and isooctane were measured and the results compared with the values calculated from vapor pressure measurements.
Properties of a Cadmium Sulfide Photorectifier
Authors: Reynolds D. C. , Greene L. C. , Antes L. L.
Published: January 2005

Measurements on a CdS photorectifier show it to have a high resistance in both the forward and reverse directions in the dark. Under illumination considerable conductivity in the forward direction is observed. Light to dark current ratios of 106 have been observed. The spectral response of the cell shows two peaks, one at the absorption cutoff the other at 5600 A with the sensitivity tailing off toward the red and infrared. The gain of the cell measured as a function of radiation intensity can be expressed empirically as a double exponential. The mechanism of the cell is explained on the basis of a model involving the formation of a quasi-intrinsic region by diffusion of the barrier into the crystal.
Out-of-Plane CH Vibrations of Benzene Derivatives
Authors: Shimanouchi Takehiko , Kakiuti Yuzo , Gamo Itaru
Published: January 2005

The normal coordinate treatment is made of the infrared active out-of-plane CH vibrations for various benzene derivatives. Frequencies calculated with the use of the out-of-plane force constants for benzene are in good agreement with the observed values. Intensities of these bands are also dealt with. The result confirms that the CH bond has the sign of polarity opposite to that of the carbon-halogen bonds.
Hindered Rotation in Molecules with Relatively High Potential Barriers
Authors: Hecht Karl T. , Dennison David M.
Published: January 2005

The theory of hindered rotation has been applied to the type of asymmetric molecule in which the hindering barrier is high enough so that the hindered rotation splittings of the energy levels are small compared with the rotational energies but yet large enough to be observable in the microwave spectrum. The specific type of molecule considered consists of a rigid asymmetric component which may undergo a hindered rotation about the symmetry axis of a rigid symmetric component where the symmetric component is in addition assumed to have threefold symmetry and the asymmetric component at least a plane of symmetry containing the symmetry axis of the symmetric component. An example might be the acetaldehyde molecule, CH3CHO.

In principle, the theory developed by Burkhard and Dennison can be used directly but in practice the method is difficult to apply to such a molecule since the matrix elements of the Hamiltonian used previously do not degenerate naturally or easily to those for the rigid asymmetric rotator in the infinite barrier limit. In the present treatment a transformation is made on the Hamiltonian whereby this complication is avoided and the resulting calculations are greatly simplified.

It is found that the spectrum is essentially that of the rigid rotator with the important exception that all the strong lines are split into two components. For the low J transitions specific formulas have been derived for these splittings which are relatively simple functions of the barrier height, the principal moments of inertia, and two additional parameters involving the molecular dimensions and the masses. The barrier height can thus be deduced from the observed splittings without the use of the somewhat cumbersome machinery needed in the general case.
Vibration-Hindered Rotation Interactions in Methyl Alcohol. The J=0→1 Transition
Authors: Hecht Karl T. , Dennison David M.
Published: January 2005

The hindered rotation fine structure of the J=0→1, K=0→0 transition which has been observed by Venkateswarlu, Edwards, and Gordy in normal methanol as well as in five additional isotopic species can be understood only qualitatively on the basis of earlier investigations of the theory of hindered rotation in methanol. It has been shown that the frequency separations between the various torsional transitions and the splitting of each of these can be explained quantitatively by including in the theory the effects of the vibration-hindered rotation interactions during the rotation of the whole molecular framework in space. The effects of the asymmetry of the rigid hindered rotator, the Coriolis interactions, and the centrifugal distortion of the molecule are discussed separately. A frequency formula for the transition is derived which contains essentially only four new rotational constants. Three of these depend solely upon the known structure of the molecule and the elastic force constants and can therefore be calculated from a knowledge of the vibrational spectrum. Since this latter has never been analyzed in more than a rough way some small adjustments have been made in the indicated values of the elastic constants which are within the limits of uncertainty. This adjustment is made for the normal molecule after which the three rotational constants are calculated for the remaining isotopic species without further adjustment. The fourth constant in the frequency formula describes the dependence of the barrier height upon the normal coordinates and is the only constant which must be determined empirically for each isotopic species. It has thus been possible to predict the 30 observed separations and splittings with the aid of essentially only six empirical constants. The agreement with experiment is remarkably good with one possible exception where the theory predicts for the fully deuterated methanol a very large splitting of the normal state line whereas the line in question is observed to be single. It is not improbable, however, that the large splitting actually exists and that the second component lay too far away to be recognized.
Vibrational Spectra and Structure of Solid Sulfamic Acid and the Sulfamate Ion
Authors: Vuagnat A. M. , Wagner E. L.
Published: January 2005

The infrared spectra of finely powdered samples in pressed disks of KBr have been obtained for sulfamic acid, sodium and potassium sulfamates, and the corresponding deutero-compounds in the region from 4000 to 500 cm—1 at several temperatures. Satisfactory vibrational assignments could be made for the zwitterion model of the acid, H3N+–SO3—, with site symmetry in the crystal of C1 in agreement with x-ray data. The sulfamate ion spectra can satisfactorily be interpreted on the basis of the C8 model, H2NSO3—. The N–S stretching modes were found at somewhat lower frequencies than previously postulated, 682 and 790 cm—1, respectively, for the acid and salt.
Concerning the Electron-Withdrawing Power and the Electronegativity of Groups
Authors: Taft Robert W.
Published: January 2005

The polar substituent constants, σ*, obtained recently by Taft from reactivity considerations are discussed. Several qualitative relationships of σ* values to substituent constitution are established. These relationships relate quantitative correlations of the effect of structure on reactivity to concepts of bonding and electronegativity. The Mulliken concept of electronegativity is supported.

The relatively large electron-withdrawing powers of Cl, Br, and I in bonds to carbon suggest the participation of the d orbitals of the valence shell. A discrepancy is noted between σ* values (and Mulliken's electronegativities) and the group electronegativities proposed by Dailey and Shoolery on the basis of proton nuclear magnetic resonance shifts in ethyl and methyl derivatives.
Heat Transfer in Chemically Reacting Mixtures. I
Authors: Hirschfelder Joseph O.
Published: January 2005

If a chemically reacting mixture is confined between two parallel plates, one hot and the other cold, the temperature and the chemical composition at a point, as well as the over-all heat flux, depend upon the rates of both the homogeneous reactions in the gas phase and the heterogeneous reactions on the surfaces. However, if the reaction rates are fast in either the forward or the reverse direction, the assumption of local chemical equilibrium (which is equivalent to the thermodynamics of irreversible processes) is found to be very good. Under such conditions the heat conductivity behaves as though the reacting gas mixture were a pure substance with an effective coefficient of thermal conductivity. A simple equation is given for this effective coefficient of thermal conductivity. Detailed examples are given for a unimolecular rearrangement A⇄B and for the dissociation of oxygen, 02⇄20. The analysis applies equally well to liquid and to gaseous mixtures.
Metastable Transitions and Collision-Induced Dissociations in Mass Spectra
Authors: Rosenstock H. M. , Melton C. E.
Published: January 2005

A number of new metastable transitions have been identified in the mass spectra of n-butane and i-butane. The appearance of various metastable transitions was discussed in terms of the quasi-equilibrium theory of mass spectra and the energetics of ionic decomposition processes. A study of the pressure independence of metastable transitions revealed the existence of several collision-induced dissociations. Some similarities of these processes to electron impact-induced dissociations were pointed out. Approximate relative cross sections were determined for the various collision processes.
Measurements of Self-Broadening in HCN
Authors: Pigott M. T. , Rank D. H.
Published: January 2005

A high-resolution directly recording grating spectrometer has been used to measure the line breadths of absorption lines in both the P and R branches of the 002 band of HCN. The observed line breadths, corrected for Doppler and instrument broadening, indicate that the earliest classical theory of Lindholm predicts the correct J dependence of pressure broadening between J=0 and J=25. The observed pressure broadening appears to be sensibly independent of J for J=27 to J=34. Hence the lines fail to become extremely narrow as J gets large, the line narrowing being a phenomenon required by existing theories which consider only J-dependent terms. The high J half-width, 0.0055 cm—1/cm Hg, is nearly equal to the term which must be added to Lindholm's earliest classical expression to bring it into agreement with observations at the band maximum. Present measurements agree well with the J=0 to J=1 microwave measurement by Smith et al. and also with the uncorrected line breadths measured at 580 mm Hg by Lindholm.
Thermodynamic Functions of Some Simple Fluorine Compounds
Authors: Potter Robert L.
Published: January 2005

The thermodynamic functions of F(g), F2(g), H1F(g), D2F(g), and the naturally occurring isotopic mixture of H1F(g) and D2F(g) have been calculated for these substances in the ideal gas state from 298.16°K to 5000°K by standard methods of statistical mechanics using available spectroscopic data.
Application of the Method of Deformed Atoms in Molecules to the Hydrogen Molecule
Authors: Arai Tadashi
Published: January 2005

The method of deformed atoms in molecules, which has been proposed in the preceding paper, is applied to the hydrogen molecule. Two structures, the neutral and ionic ones, are considered. It is assumed that the best approximate functions are made up from the hydrogen-like functions, and favorable correction factors are sought so as to bring about the results appertaining to the good range. Energy drops of 1.5∼1.7 ev are then obtained, which are satisfactory results as compared with that of 0.16 ev in Moffitt's method. Discussion is given about the function of the ionic term, in which the axial correlation is taken into account.
Studies in Nonequilibrium Rate Processes. I. The Relaxation of a System of Harmonic Oscillators
Authors: Montroll Elliott W. , Shuler Kurt E.
Published: January 2005

As a part of an investigation of nonequilibrium phenomena in chemical kinetics a theoretical study has been made of the collisional and radiative relaxation of a system of harmonic oscillators contained in a constant temperature heat bath and prepared initially in a vibrational nonequilibrium distribution. An exact solution has been obtained for the general relaxation equation applicable to this system and expressions have been derived for the relaxation of initial Boltzmann distributions, Poisson distributions, and δ-function distributions as well as for the relaxation of the moments of the distributions. Using the latter result, explicit expressions are given for the relaxation of the internal energy of the system of oscillators and for the time dependence of the dispersion of the distributions.
Density of Liquid He4
Authors: Kerr Eugene C.
Published: January 2005

The density of He4 under its own vapor pressure has been measured between 1.2°K and 4.4°K by a direct method. The results are given in smoothed tabular form and are compared with the results of previous measurements. An attempt has been made to derive a usable value for the critical density from the liquid and vapor densities at lower temperatures.
On the Second-Order Decay of the Thermoluminescence of Polycrystalline Materials
Authors: Weyl Peter K.
Published: January 2005

The results of an isothermal decay and glow-curve experiment for a thermoluminescent material having second-order kinetics have been investigated. In contrast to the first-order case, the location of the peak of the glow curve depends on the initial trap density. The effect of a distribution of trap densities for a polycrystalline material is investigated. It is found that for a narrow distribution function, a plot of the reciprocal of the square root of the light intensity versus the time in the isothermal decay experiment will give a straight line whose slope and intercept will depend on the distribution function. The location of the peak of the glow curve is not materially affected by the distribution function, and from its location and the energy of the trap depth, a parameter proportional to the initial trap density and independent of the optical efficiency can be determined.

Plots of first- and second-order generalized glow curves are presented from which the parameters of an experimental curve can be determined.
Vibrational Intensities. VII. Ethane and Ethane-d6
Authors: Nyquist Irene M. , Mills I. M. , Person W. B. , Crawford Bryce
Published: January 2005

Absolute intensity measurements have been made on the fundamental vibrations of C2H6 and C2D6, using the extrapolation method of Wilson and Wells and using nitrogen at pressures up to 50 atmospheres to broaden the bands. The absorption coefficient was integrated against the logarithm of the frequency. Normal coordinates were calculated from the potential function of Hansen and Dennison, and were used to interpret the results in terms of quantities (∂p/∂Si) giving the change of dipole moment with respect to the symmetry coordinates Si. Consistency of data between the isotopes was used both to eliminate ambiguities in the interpretation, and as a criterion in separating overlapping pairs of absorption bands. The results have been interpreted in terms of bond effective moments.
Flexibility of Chemical Bond as Revealed by the Rocking Frequencies in Ethylene
Authors: Shimanouchi Takehiko
Published: January 2005

The CH2 rocking frequencies in ethylene are explained by taking the flexibility of the CC bond into account. Mathematical expressions for the bond flexibility are dealt with. The difference between the Urey-Bradley field and the orbital force field is discussed and it is concluded that in the case of ethylene and its derivatives the inclusion of simple correction terms in the Urey-Bradley field can also cover the case of the orbital force field.
Dielectric Absorption and Phase Changes in an Aliphatic Ester in the Waxy Form
Authors: Dryden J. S.
Published: January 2005

The dielectric absorption has been examined in an aliphatic ester, butyl stearate, when in the waxy, transcent form. The measurements reveal the existence of three phases with well-defined transition temperatures; thermal studies and x-ray powder photographs confirm the existence of the three phases. There are three absorption regions in each phase, one possessing a very high activation energy. The possible mechanisms of the absorptions are discussed briefly.
Vibrational Spectra of Molecules and Complex Ions in Crystals. IX. Boric Acid
Authors: Hornig D. F. , Plumb R. C.
Published: January 2005

The infrared spectrum of boric acid was studied at 25°C and —195°C in the form of randomly oriented crystallites and as a single crystal section at 25°C. The spectrum can be interpreted as skeletal vibrations of B(OH)3 molecules plus the hydrogen vibrations, which are those of the hexagonal O–H≡O rings. The spectrum demonstrates that the symmetry about the B atoms is less than trigonal. There is no evidence of proton disorder.
Scattering of Low Velocity Molecular Beams in Gases
Authors: Mason Edward A.
Published: January 2005

A large number of partial and total molecular scattering cross sections have been calculated numerically for molecules obeying an exp-six potential, consisting of an exponential repulsion term and an inverse sixth power attraction term. The tabulations cover a wide range of scattering angles, energies, and potential parameters, and can be used to obtain information about intermolecular forces from the results of experiments on the scattering of low velocity molecular beams in gases. The calculations are classical throughout, and quantum effects are ignored, but an approximate formula is given for estimating where the classical calculations break down in any particular case. The use of the tables is illustrated by a comparison with Knauer's results on the scattering of beams of H2 in mercury vapor.
Microwave Spectrum and Structure of Formic Acid
Authors: Lerner R. G. , Dailey B. P. , Friend J. P.
Published: January 2005

The microwave spectra of five isotopic species of formic acid have been investigated, and values of the rotational constants B and C have been obtained. For HC12OOH, B=12 055.1 Mc, C=10 416.0 Mc; for HC12OOD, B=11 762.5 Mc, C=9970.1 Mc; for DC12OOH, B=12 055.6 Mc, C=9955.8 Mc; for DC12OOD, B=11 759.9 Mc, C=9534.1 Mc; and for HC13OOH, B=12 053.7 Mc, C=10 378.9 Mc. The following structural parameters have been fitted to these rotational constants: rC–H=1.085 A, rC=O=1.245 A, rC–O=1.312 A, rO–H=0.95 A, ∠OCO=124°18′, ∠COH=107°48′. The C=O bond has been estimated to have 75% double-bond character. The torsional frequency was found to be 667±41 cm—1 and a barrier height of roughly 17 kcal/mole is indicated.
Spectra of the Alkali Halides. III. Electronic Spectra of Lithium Chloride, Lithium Bromide, and Lithium Iodide
Authors: Berry R. Stephen , Klemperer William
Published: January 2005

The ultraviolet absorption spectra of the molecules LiCl, LiBr, and LiI have been observed in the quartz region. These spectra, which appear as continua with associated diffuse bands, have been interpreted as arising from excitations to two excited states of the molecules. The symmetries and potential curves for these states are discussed.
Gaseous Detonations in Mixtures of Cyanogen and Oxygen
Authors: Peek H. Milton , Thrap R. G.
Published: January 2005

Precise experimental data are compared with precise theoretical values for the detonation velocities of several gaseous mixtures of cyanogen and oxygen. The results of this comparison show that these detonation processes are pathological in the sense of the theory of Kirkwood and Wood. Because of the lack of chemical kinetic data, it is not possible to calculate correct detonation velocities for these pathological detonations. Therefore, the determination of detonation velocities is not a worthwhile method for the determination of precise values of thermodynamic properties in mixtures of cyanogen and oxygen.
Foreign Gas Pressure Broadening of Linear Molecules
Authors: Perkins Kenneth L. , Bushkovitch A. V. , Kieffer L. J.
Published: January 2005

Calculations have been made for the general cases of a linear polar molecule interacting with the following foreign molecules: monatomic, linear nonpolar, and linear polar. The interactions of importance are the first-order London dispersion force for the first two cases and the combined dipole-quadrupole, quadrupole-quadrupole, and first-order London dispersion forces for the third case. In the case of OCS with He, O2, and N2O the calculations yield 3.22, 5.41, and 7.41 A, respectively, in reasonable agreement with experiment.
Mass Spectrum and Vapor Pressure of Pentaborane-d9
Authors: Shapiro I. , Ditter J. F.
Published: January 2005

The complete mass spectrum of pentaborane-d9 and a partial mass spectrum of pentaborane-d8 have been calculated from the spectra of a series of samples of different hydrogen content. The vapor pressure for pentaborane-d9 containing 3.9% of the B5D8H species can be expressed by the equation log10Pmm=9.46916 — 0.0028783T — 1870.70/T over the temperature of — 25°C to +56°C. The melting point is — 47.0°C. By way of comparison the vapor pressure equation for pentaborane is log10Pmm=9.49191 — 0.0028956T — 1881.29/T; the melting point is — 46.8°C.
Diffusion of Nickel in Nickel Oxide
Authors: Shim Moon Taik , Moore Walter J.
Published: January 2005

Diffusion coefficients for nickel in polycrystalline and monocrystalline nickel oxides have been measured by the surface-activity method from 1000 to 1400°C in air. Within experimental uncertainty the values D=4.4×10—4 exp(—44.2/RT) fit both cases. These results indicate that the oxidation of nickel under comparable conditions of T and P proceeds via lattice diffusion of Ni through NiO.
Alpha-Induced Decomposition of Ammonia. II. Effects of Variations in Intensity and Pressure
Authors: Burtt Benjamin P. , Zahlan Antoine B.
Published: January 2005

The alpha-induced decomposition of ammonia was studied as a function of pressure (70–740 mm) and intensity. The ion yield was found to increase both with increasing intensity and decreasing pressure. The variation with intensity was more pronounced below 200 mm than at higher pressures.

Several models were examined to account for the experimental results. The decrease in the yield with increasing pressure was due to the deactivation of NH3* generated by the reaction NH2+H→NH3*.

At all intensities used in this work, gas phase ion recombination was negligible. The positive ions were assumed to react with NH3 to form NH4+ which was neutralized at the wall.

At sufficiently high pressure and intensity, the NH2 radicals reacted homogeneously in the gas phase, but at low pressure and intensity, wall reactions became important.

This ``intensity'' effect was caused by the ions and does not appear in photolysis. The ion-molecule reactions generate the NH4+, the pressure controls the diffusion process, and the intensity determines the relative importance of the gas phase and the wall reactions. The intensity effect is a function of all four variables.

On the basis of the reaction scheme and the present knowledge of the mass spectrum, it was possible to calculate a lower limit for the ion yield.
Effect of Hydrogen Bonding on the Near Ultraviolet Absorption of Naphthol
Authors: Nagakura S. , Gouterman M.
Published: January 2005

The effect of hydrogen bonding on near ultraviolet absorption spectra of α- and β-naphthol, which were used as the proton donor, was studied. Triethylamine, ethyl ether, and nitromethane were employed as the proton acceptor. Absorption measurements were made with ternary solutions which contain small amounts of proton donor and acceptor in n-heptane. The results show that both La and Lb bands decrease gradually with the increasing concentration of proton acceptor and new bands, which are caused by the hydrogen bonded proton donor molecule, appear on the longer wavelength sides of original bands. Using this change of absorption spectrum, the equilibrium constant between proton donor and acceptor and wavelength shifts due to hydrogen bonding were evaluated. From the evaluated values of these two quantities, it was concluded that the proton accepting power decreases in the order of triethylamine [N(C2H5)3]>ethyl ether [O(C2H5)2]>nitromethane (H3CNO2). On the basis of this proton accepting ability, it was discussed that hydrogen bonding is not purely electrostatic in its origin but the charge transfer or delocalization mechanism contributes it to an important extent.
Nuclear Magnetic Relaxation in 1,2-Dichloroethane
Authors: Linder Solomon
Published: January 2005

Analysis of thermal relaxation times in solid and liquid 1,2-dichloroethane suggests the following:

(1) The mechanism causing thermal relaxation in the solid is a partial rotation of the molecule about the molecular axis (which is approximately the C–C axis) against a potential barrier of about 1.5 kcal per mole.

(2) It is likely that the narrowing of the resonance line is a result of the completion of this partial motion.

(3) At the melting point, a drop in the thermal relaxation time of about an order of magnitude occurs.

(4) In the liquid, a new motion has set in, characterized by a lower activation energy (roughly 0.6 kcal/mole). This motion may be end-over-end tumbling.

The spin-lattice relaxation time (``thermal'' relaxation time) in the solid ranges between 1 and 20 sec, and its length permits its measurement by a method which is slightly different from the conventional technique. This technique utilizes the fact that, immediately upon application of the radio-frequency field, the magnetization of the sample decays with a time which can be related to the thermal relaxation time and to the strength of the radio-frequency field. The measurement is a direct measurement of a characteristic time of the sample, and is therefore more reliable than the conventional indirect measurement.

The technique also enables one to calibrate the radio-frequency field more easily.
Modifications of the Cs Absorption Spectrum Due to Interatomic Interactions
Authors: Jefimenko Oleg , Ch'en Shang-Yi
Published: January 2005

Absorption spectra of Cs in the presence of H2, D2, N2, He, Ne, A, Kr, Xe, methane, ethane, propane, n-butane, n-pentane, n-hexane, n-heptane, n-octane, and benzene were investigated following a similar work with Rb. It was found that the spectra of all these mixtures of Cs and foreign gas exhibit diffuse bands in the neighborhood of certain Cs atomic lines. Over one-hundred such bands were identified, the positions of the bands were measured, and some of the regularities in the occurrence of the bands were determined. The results of this investigation in general were found to be in qualitative agreement with the statistical theory of pressure broadening of the atomic lines if both the attractive and the repulsive interatomic forces are taken into account. It is, however, not certain that the statistical theory is capable of explaining the observed phenomena in their entirety.
Two-Center Dipole Moment Integrals in Terms of C Functions
Authors: Hamilton Walter C.
Published: January 2005

The dipole moment integrals for Slater-type atomic orbitals are conveniently and concisely expressed in terms of the C functions introduced by Ruedenberg, Roothaan, and Jaunzemis in their treatment of the two-center hybrid integrals. Explicit formulas in terms of both the C functions and the usual A and B functions are given for all such integrals involving orbitals with quantum numbers one and two.
Interaction between Sulfur Dioxide and Polar Molecules. I. Systems Containing Aliphatic Alcohols, Ethers, or Benzene in Carbon Tetrachloride
Authors: de Maine P. A. D.
Published: January 2005

The absorption band of sulfur dioxide near 2800 A in mixed solvents of benzene, aliphatic alcohols, or ethers with carbon tetrachloride is probably in part the result of a donor-acceptor complex with sulfur dioxide as acceptor.

The characteristic constants for the MeOH, EtOH, n-PrOH, n-BuOH, and benzene complexes with sulfur dioxide, and the heats of formation of the benzene and ethanol complexes with sulfur dioxide in carbon tetrachloride have been estimated. The effect of atmospheric water vapor on these systems is also discussed.
Interaction between Sulfur Dioxide and Polar Molecules. III. Water-Ethanol-Sulfur Dioxide and Water-Sulfur Dioxide Systems
Authors: de Maine P. A. D.
Published: January 2005

It is shown that the temperature dependence of the ultraviolet absorption spectra for water-sulfur dioxide solutions cannot be explained by the theories of Ley and Konig or Boyd-Campbell and Maass. Qualitative arguments show that the mechanism, (SO2)gas⇀lhdSO2+H2O⇀lhdcomplex⇀lhdH2SO3⇀lhdH++-HSO3⇀lhd2H++-2SO3, does explain the spectroscopic behavior of dilute sulfur dioxide solutions.

A linear relation is reported between the heat of solution, calculated from vapor pressure data, and the smallest effective molecular diameter of several gases.

Attempts to analyse the absorption spectra of the water-ethanol-sulfur dioxide solutions in terms of the separate systems, EtOH+SO2⇀lhdcomplex1 and (SO2)gas⇀lhdSO2+H2O⇀lhdcomplex2⇀lhdH2SO3⇀lhdH++-HSO3 are reported. These results are explained by the new liquid lattice theory.
Anomalous Centrifugal Distortion Coefficients in Linear Polyatomic Molecules
Authors: Nielsen Harald H. , Amat Gilbert , Goldsmith Mark
Published: January 2005

The theory of the effect of resonance, in particular Fermi resonance and l-type resonance, on the effective centrifugal distortion coefficient of a molecule for a given vibration state is developed. The theory is applied to certain cases where l-type resonance occurs and to certain cases where both l-type resonance and Fermi resonance occur. No instances appear to have been investigated where Fermi resonance occurs without l-type resonance being present. The agreement between the theory and the experimental results appears to be satisfactory to the approximation of the theory.
Madelung Constants of Some Cubic Crystals
Authors: Benson G. C. , van Zeggeren F.
Published: January 2005

A simple method for evaluating the Madelung constant of a CsCl-type crystal is described. The Madelung constants of CaF2-type and ZnS-type lattices are computed to ten decimal places from linear relations between the Madelung constants of these and NaCl- and CsCl-type crystals.
Vibrational Spectrum of Disilane
Authors: Bethke George W. , Wilson M. Kent
Published: January 2005

Raman spectra of the liquid and infrared spectra of the gaseous phase have been obtained for Si2H6 and Si2D6. With the exception of the torsional mode all fundamental frequencies have been observed and assigned to the proper normal modes. The coarse rotational structure of the perpendicular bands, ν8 and ν9, has been resolved and the corresponding Coriolis coupling coefficients determined. Comparisons with the spectra of ethane and digermane have been made.
Zinc Oxide Photoconduction, an Oxygen Adsorption Process
Authors: Melnick Donald A.
Published: January 2005

Photoconductive rise and decay curves of porous sintered zinc oxide are studied as a function of time (0.3 to 107 sec), ambient oxygen pressure (5×10—5 to 760 mm), temperature (110° to 373°K), incident light intensity (factor of 103), and various cycling procedures in regard to illumination. The photoconductivity is shown to be entirely due to the desorption of chemically adsorbed oxygen atoms from the surfaces of the porous sample. Light of wavelength near the fundamental absorption edge forms electron-hole pairs of which the hole is captured by the oxygen, converting the oxygen to physically adsorbed. The physically adsorbed oxygen easily desorbs and the electron remains to increase the conductivity. The kinetics of the adsorption process when the light is removed are found to obey the Elovich equation, dq/dt=a exp(—bq), where q is the density of adsorbate, and a and b are constants. It is believed that the limiting process is electron transfer through the Schottky barrier, since it results in an equation equivalent to the empirical one above.

Experimentally a continuous spectrum of time constants is found. A technique has been developed for analyzing experimental curves into component time constant processes. The Elovich equation results in time constants depending upon the intensity of illumination. The continuous spectrum of time constants can therefore be attributed to this variation of intensity with depth in the sample.