bluuebunny/crossref_metadata_2025 huggingface dataset:
Electronic Structure of Carbon Monoxide
Authors: Brion Hélène , Moser Carl
Published: January 2005

The LCAO—MO SCF orbitals for carbon monoxide have been calculated with 1s, 2s, and 2p Slater atomic functions, using best atom (Roothaan) exponents. All atomic integrals have been calculated. While all the orbitals are orthogonal, the inner shells have been given a fixed form. The calculated binding energy (using these SCF orbitals for the molecular energy and the same atomic functions for atomic energy) is about 40% of that observed. A limited configuration interaction calculation gives about 55% of the observed binding energy. Both the single determinant and the CI wave function predict a dipole moment which is in agreement with the observed sign C—O+, but the error in magnitude is rather large. The atomic populations suggest the sign of the dipole moment to be C+O—, in agreement with Malone's rule.

The ionization energies have been calculated and the agreement with experiment is very satisfactory. Some of the observed lower electronic transitions can be understood by using single configurations constructed from these SCF orbitals, but, before a more complete analysis of the spectrum can be attempted, it may be necessary to introduce atomic functions from the M shell.
Exchange of Radiochlorine between Hydrogen Chloride and Carbon Tetrachloride. ``Red Form'' of Solid Hydrogen Chloride
Authors: Pearson Irving M. , Garner Clifford S.
Published: January 2005

Radiochlorine-36 has been used to investigate the HCl*–CCl4 exchange in systems of high purity at 22–35°C in the dark and in sunlight for exchange times up to 200 and 117 days, respectively, with solutions 0.14–0.18 f in HCl and 10 f in CCl4. The exchange rate law is not known, but results have been presented in terms of an assumed bimolecular rate law, R=k(HCl)(CCl4). For the dark exchange, k≤2×10—11 liter mole—1 sec—1, an upper limit which is about 4×107 times smaller than the upper limit set by earlier workers. There is no evidence that the exchange is accelerated in sunlight. The so-called ``red form'' of solid HCl was observed during the work, as well as solid HCl which was yellow. An apparent red-inducing impurity was found separable from most of the HCl by slow vacuum distillation of the latter from a —140°C bath to a trap at —196°C. The solid HCl distillate was colorless and failed to develop a red color even in six flash freezings at —196°C, whereas the pale yellow HCl residue from the distillation gave a rose-red color on being flash frozen at —196°C. Volatility characteristics of the latter apparent impurity suggest that, if it be an oxide of nitrogen as proposed by Clusius and Haimerl, it is probably not NO but rather N2O or possibly N2O3. If the red color arises from imperfection color centers in the crystal lattice of HCl, as suggested by Johnston and Martin, generation of the color seems to require both reasonably rapid freezing at or near —196°C and the presence of an impurity separable from the HCl by a proper distillation. Consequently the flash-freeze test for traces of HCl in other substances must be interpreted with caution.
Interactions between Molecules Adsorbed on a Surface
Authors: Sinanoğlu Oktay , Pitzer Kenneth S.
Published: January 2005

The intermolecular potential energy between two inert gas molecules is considerably altered when these molecules are next to a solid surface as in physical adsorption. The change in the interaction is evidenced by the additional long-range repulsion that is often observed between the molecules of a monolayer and also by the additional attractions that must play a role in multilayer formation.

In this article, the two-molecule-surface potential is derived from quantum mechanical third-order perturbation theory. It is shown that this potential consists of two parts just as the energy giving the van der Waals attraction of a single molecule to a surface does. The first part exists only when the surface has a net electrostatic field and this is equivalent to the classical polarization effect. The second part arises from the fluctuations of the surface fields and is of the same origin as the dispersion forces. The third-order energy, i.e., the new intermolecular interaction caused by the surface, is directly related to the zero-coverage heat of adsorption and except for this experimental quantity, the results do not require specific assumptions about the surface. Thus, the theory is applicable to either metal or insulator surfaces. When both the two-molecule-surface and the one-molecule-surface interactions are available experimentally (for example, from the application of virial coefficients treatment in physical adsorption) the electrostatic field of the surface can be estimated.

The fluctuation or dispersion part of the third-order energy is shown to yield a repulsion between two molecules in a monolayer that amounts to 20–40% of the gas phase Lennard-Jones potential minimum ε0. The same energy yields an additional attraction of about 10–20% of ε0 when the two molecules are on top of one another as in multilayer formation. The theory is applicable also when more than two molecules at a time need be considered on the surface.
Transferability of Urey-Bradley Force Constants. II. Carbonyl Halides and Related Molecules
Authors: Overend John , Scherer J. R.
Published: January 2005

Urey-Bradley force constants have been fitted to the observed vibrational frequencies of COF2, COCl2, and COBr2 by the method described in the previous paper. These force constants have been used to calculate the frequencies of COClF, COBrF, and COBrCl. Normal coordinates and the potential energy distribution among the various Urey-Bradley coordinates have also been calculated. It is found that, despite the fact that the carbonyl stretching frequencies fall over a range of 100 cm—1, the carbonyl stretching force constant is essentially the same for all molecules in the carbonyl halide series.
Measurements of Multicomponent Diffusion Coefficients for the CO2–He–N2 System Using the Point Source Technique
Authors: Walker R. E. , deHaas N. , Westenberg A. A.
Published: January 2005

Measurements of the diffusion coefficient for a trace of carbon dioxide in a mixture of helium and nitrogen of varying composition have been made at room temperature and atmospheric pressure using the point source technique. The results are shown to be in agreement with the results of Fairbanks and Wilke in that an equation of the form Di−mix=[∑k lim i≠k(xk/Dik)]−1 can be used to relate the diffusion coefficient of a trace of species i in a mixture of composition given by the mole fraction xk to the binary diffusion coefficients Dik. Some data are presented on the separation of the mixture in the diffusion zone.
Thermodynamic Excess Functions for Electrolyte Solutions
Authors: Friedman Harold L.
Published: January 2005

A system of excess functions is developed for electrolyte solutions and other solutions with an essentially unsymmetrical solvent-solute relation. These new functions vanish for a solution whose practical (molal scale) osmotic coefficient is unity at all compositions, temperatures and pressures. The use of these excess functions offers some advantages over other methods of comparing Mayer's ionic solution theory with experiment, of representing the properties of solutions of single or mixed electrolytes, and of making qualitative interpretations of the molecular basis of thermodynamic properties.

Graphs showing the ionic-strength dependence of the excess free energy, excess enthalpy, excess entropy, and excess volume are given for several aqueous solutions of single electrolytes up to 6 molal. Experimental values of the cluster integral sum, the characteristic function of the Mayer theory, have also been calculated. The concentration dependence of this function is very similar to that of the excess free energy.
Mass Spectrometric Investigation of the Sublimation of Molybdenum Dioxide
Authors: Burns R. P. , DeMaria G. , Drowart J. , Grimley R. T.
Published: January 2005

A mass spectrometric investigation of the vapor in thermodynamic equilibrium with powdered molybdenum dioxide has shown the vapor phase to consist, in decreasing order of importance, of the species MoO3, (MoO3)2, MoO2, and (MoO3)3. The heats, entropies, and free energies of reaction have been determined for the reactions (T=1600°K): 32x MoO2(s)→(MoO3)x(g)+12x Mo(s)         where x=1, 2, 3MoO2(s)→MoO2(g)         ΔHT=134.4±7 kcal/mole2MoO3(g)→(MoO3)2(g)         ΔHT=−110.2±8 kcal/mole3MoO3(g)→(MoO3)3(g)         ΔHT=−222.8±13 kcal/moleFor the case x=1, 2, 3 the ΔHT's are 121.8±3, 133.4±7, and 142.6±13 kcal/mole, respectively. Entropies of the gaseous molecules MoO3, (MoO3)2, (MoO3)3, and MoO2 at T=1600°K are 96.6, 151.0, 201.2, and 85.5 eu, respectively. In addition, the atomization energies (ΔH0o) for the reactionMoOx(g)→Mo(g)+xO(g)were calculated to be 277.4±7 and 419.7±10 kcal/mole for x=2 and 3, respectively.
Refractive Index and Dispersion of the Benzene-Carbon Tetrachloride System
Authors: Wood Scott E. , Masland Charles H.
Published: January 2005

The refractive indices of the benzene-carbon tetrachloride system have been measured at seven different wavelengths in the visible region. These indices show only slight departure from linearity in the mole fraction. The molar refractions, calculated according to the Lorentz-Lorenz equation, are not additive in the mole fraction. Moreover, no simple relation between the molar refractions and the frequency of the light source is obtained.
Effect of Metal Atom Perturbations on the Luminescent Spectra of Porphyrins
Authors: Allison Jean B. , Becker Ralph S.
Published: January 2005

The low-temperature emission spectra of the dimethyl ester of mesoporphyrin IX and its divalent derivatives of cobalt, nickel, copper, zinc, palladium, cadmium, and barium have been obtained. Magnesium etioporphyrin(II) and zinc phthalocyanine were also investigated. The divalent silver mesoporphyrin was also studied, but no luminescence was obtained for this compound. Considerations of the relative lifetimes of fluorescence and phosphorescence of the various derivatives permit qualitative deductions to be made regarding magnetic susceptibility. Certain qualitative information on metal-porphyrin bonding is presented based on the comparative intensities of fluorescence and phosphorescence. Anomolous emission characteristics of several of the metallo-porphyrins are tentatively interpreted in terms of crossing of a first excited state and the ground state.
Effect of Solid Propellant Compressibility on Combustion Instability
Authors: Bird J. F. , Haar L. , Hart R. W. , McClure F. T.
Published: January 2005

The recent theory of the interaction of sound with a burning propellant surface is extended to include density fluctuations of the solid propellant. Both compressibility and thermal expansion are treated, but the latter is found to be less important than the former. For reasonable values of the compressibility, it is shown that the acoustic response, Real (μ̃1/ε̃), of the surface is reduced by as much as 0.1 in a broad range of frequency around several Kc. A simple low-frequency approximation for the burning surface response is also discussed.
Theory of Saturation in Electron Spin Resonance Spectra
Authors: Stephen Michael J. , Fraenkel George K.
Published: January 2005

A theory of saturation in electron spin resonance spectra exhibiting hyperfine splitting is presented. This theory is used to study the saturation of free radical spectra in solution, and a variety of relaxation processes are investigated. It is shown that motional modulation of the intramolecular electron-nuclear anisotropic dipole—dipole interaction introduces a relation between the saturation parameters and the hyperfine components that varies symmetrically about the center of the spectrum and causes a smaller degree of relaxation for the components in the central portion of the spectrum than for those in the wings. This relaxation mechanism introduces a greater dependence on nuclear spin state for radicals with several magnetic nuclei than for radicals with only one such nucleus. It is also shown that a cross term between this intramolecular dipolar interaction and motional modulation of the anisotropic g tensor introduces a relaxation that varies linearly from one side of the spectrum to the other. Numerical values of the relaxation-induced transition probabilities are estimated for the benzene negative ion, and tables are given from which saturation factors can be computed for a variety of conditions for several different spin systems. The relation between the spin-lattice relaxation time T1 and the parameters which determine saturation is discussed, and it is pointed out that these quantities are not equivalent in systems exhibiting cross relaxation.
Thermal Conductivity of Helium and Hydrogen at High Temperatures
Authors: Blais Normand C. , Mann Joseph B.
Published: January 2005

A steady-state hot wire method for measuring the thermal conductivity of light gases in the temperature range 1200° to 2100°K is described. In contrast to other methods, free convection currents and large temperature gradients occur; convection effects are shown to be negligible, and the experimental procedure for eliminating the large gradient effects is described. The thermal conductivity of helium is found to follow the equation λ×106=991+0.678(T—1200) cal/sec cm deg over the temperature range covered. That for hydrogen is λ×106=1434+1.257(T—1200) cal/sec cm deg.
Diffusion of Cadmium in Pure and Cadmium Doped AgBr
Authors: Hanlon J. E.
Published: January 2005

The diffusion of Cd in pure AgBr and dilute AgBr-CdBr2 solid solutions was measured by a tracer technique using carrier-free Cd109. It was necessary to use the extremely high specific activity carrier-free isotope because the diffusion of Cd in AgBr depends sensitively on impurity concentration. The data support Lidiard's theory for the diffusion of divalent impurities in monovalent ionic crystals. From the diffusion rates in the pure material, it is possible to calculate the association energy ΔG of Cd++Ag vacancy complexes. The value of ΔG extrapolated to 0°K is estimated to be 0.21±0.04 ev. The observed concentration dependence of Cd diffusion in doped samples can be explained only if the mobility of complexes is assumed to have a strong concentration dependence. This interpretation suggests that a reappraisal of the analysis of previous electrical conductivity and thermoelectric power doping experiments, in which the mobility was assumed to be concentration independent, would be desirable.
Comparison of n and s as Fall-Off Parameters in the Slater and Rice-Ramsperger-Kassel Classical Theories of Unimolecular Reaction
Authors: Schlag E. W. , Rabinovitch B. S. , Schneider F. W.
Published: January 2005

The classical Rice-Ramsperger-Kassel integral for the unimolecular rate constant has been evaluated over a range of s values at the several values of b = 32, 36, 40 and 44. Equivalent values of s and of the Slater theory parameter n have been found by comparison of the shape of the fall-off behavior predicted by both theories in the upper region of fall-off. The equivalence diverges from the limiting relation n = 2s—1 even below n = 8. The findings are discussed briefly.
Electronic States of p-Benzoquinone. VI. Molecular Geometry in the Excited Electronic State of the 4500-A Absorption System as Derived from the Franck-Condon Principle
Authors: Anno Tosinobu , Sadô Akira
Published: January 2005

The method used for evaluating the Condon overlap integral associated with any vibronic band of an electronic absorption system of an XY2 molecule, as developed by J. B. Coon and his co-workers, is applied to more complex molecules. Thus, some information about the geometry of the excited electronic state of a complex molecule may be determined if the geometry in the ground state, the intensities of vibronic bands of the associated electronic absorption system, and normal coordinates and frequencies in both electronic states are known. The method is applied to the 4500-A absorption system of p-benzoquinone. Since the normal coordinate treatment for this molecule is only qualitatively valid, especially in its excited state, the results are expected to be more or less qualitative. If we take the resulting change of bond angles into account, the ring-bending frequency of species Au in the excited electronic state is calculated to be 438 cm—1 by the method described in Part III of this series [T. Anno and A. Sadô, Bull. Chem. Soc. Japan 31, 728 (1958)].
Principle of Corresponding States for Transport Properties
Authors: Helfand Eugene , Rice Stuart A.
Published: January 2005

The principle of corresponding states can be demonstrated by use of the autocorrelation function expressions for the transport properties and the assumption that the intermolecular potential has the form u=εu*(r/σ). The result follows from the fact that both the canonical ensemble distribution function and the solution of the mechanical equations of motion may be written in reduced variables. One finds that η*=ησ2/m½ε½, κ*=κkε½/m½σ 2, and D*=Dm½/ε½σ are universal functions of T*=Tk/ε, P*=Pσ3/ε, and in the quantum mechanical case ℏ*=ℏ/σm½ε½.
Multiple Emission Spectra of Trivalent Europium in the Scheelite Structure
Authors: Van Uitert L. G. , Soden R. R.
Published: January 2005

Spectra resulting from emission from four electronic levels are observed for members of the series Ca1–2xNaxEuxWO4. Their relative intensities are concentration dependent. Successively lower lying emission levels are quenched by what appear to be exchange interactions resulting from coupling between two or more neighboring Eu3+ ions.
Madelung Constant for K2SO4(II)
Authors: Wood Robert H.
Published: January 2005

The Madelung constants of NaCl, CsCl, and K2SO4 have been calculated with the aid of a digital computer.

The method of summing over neutral shells of atoms with each shell being composed of unit cells is used. This method allows the presence of surface dipole moments (de Boer effect) to be ignored. The results for K2SO4 allow the calculation of the Madelung constant as a function of the charge on the oxygen (Mδ=6.922+0.36ε).
Heterogeneous Nature of Reaction in Radiation-Induced Solid-State Polymerization of Acrylamide
Authors: Adler George , Reams Walter
Published: January 2005

It has been suggested that the radiation-induced solid-state polymerization of acrylamide is a heterogeneous reaction, that is, it goes by a two-phase mechanism [G. Adler, J. Chem. Phys. 31, 848 (1959) and B. Baysal, G. Adler, D. Ballantine, and P. Colombo, J. Polymer Sci. (to be published)]. According to this concept, the reaction procedes at definite sites within the crystal. After the first few reaction steps, it forms regions of pure or nearly pure polymer imbedded in pure monomer. Further reaction would take place at the interface between the two. The polymer and monomer regions would remain segregated until the crystal is completely polymerized. It has been shown previously that the reaction can take place without the crystal breaking up. The alternative to this scheme seems to be that the reaction takes place within the crystal lattice and is directed by it. This requires a more homogeneous reaction mechanism. It seems feasible, in principle to distinguish between the two mechanisms by x-ray diffraction. A single crystal technique that allows us to look at all the reflections simultaneously appeared to be most promising. It was therefore decided to run a series of rotation diagrams on a crystal in various stages of polymerization.
Transferability of Urey-Bradley Force Constants. III. The Vinylidene Halides
Authors: Scherer James R. , Overend John
Published: January 2005

Force constants have been calculated by a least-squares method for vinylidene bromide and vinylidene fluoride using complete deuterium isotopic data and a Urey-Bradley potential function. The results of this work show that the ``C=C stretching'' and ``CH2 scissors'' modes are not pure vibrations but exhibit appreciable coupling between C=C stretching and CH2 bending coordinates. Further, the molecules within the vinylidene-halide series do not seem to have constant normal coordinates and hence the frequency differences are not entirely associated with changes in the force field. It follows that in molecules of this type, it is dangerous to infer changes in bond strength from observed frequency shifts except with the aid of a complete normal-coordinate analysis.
Charge Transfer Mechanism of Reaction of Conjugated Molecules
Authors: Fukui Kenichi , Morokuma Keiji , Yonezawa Teijiro , Nagata Chikayoshi
Published: January 2005

Mathematical interrelations are found between the superdelocalizability and the Z value, i.e., two of the reactivity indexes of conjugated molecules. MO theoretical discussions on the mechanism of aromatic substitution are also made.
Calculation of Delocalization Contribution to Infrared Intensity
Authors: Jones Walter D. , Simpson William T.
Published: January 2005

Infrared intensity may be related to energies and intensities of electronic transitions by using the theory of the vibrational perturbation of electronic transitions and holding the electronic state quantum number fixed. This suggests in particular relating the infrared intensity of an appropriate normal mode to the strong ultraviolet absorption in dye-like molecules having conjugated π-electron systems. The perturbation theory is tested by applying it to a displaced hydrogen atom and the hydrogen molecule ion. The results suggest the need for modifying the theory to employ floating orbitals. A floating orbital theory of infrared intensity which still brings in ultraviolet transition energies and moments is then constructed. This theory is next applied to the model compounds H3+, H5+ and H7+ and there is predicted an extraordinarily high delocalization contribution to the intensity for the anti-symmetric stretch. Values for the dipole derivatives are calculated ranging up to 65 debyes/A.
Reactions Initiated by the β Decay of Tritium. III. The Tritium-Cyclopropane System
Authors: Gant Preston L. , Yang Kang
Published: January 2005

The β decay of tritium in the gaseous tritium-cyclopropane system initiates reactions forming various tritiated compounds. Identified products are cyclopropane, propane, propylene, isobutane, ethane, ethylene, and acetylene. Dependence of the labeling yields on T2 concentration clearly showed that energetic electrons as well as the decay species (He3T)+ initiated the labeling processes. Ionic and/or hot-atom reactions are assumed to occur to explain the effects of nitric oxide and temperature on the labeling yields.
Theory of Fused Salts
Authors: Stillinger Frank H. , Kirkwood John G. , Wojtowicz Peter J.
Published: January 2005

The properties of ionic pair distributions are investigated for a simple fused-salt model. The short-range ion core forces are assumed to be identical for both anions and cations and, although the method is capable of handling mixtures of ions with different charges, only a single fused salt of the symmetrical-valence type is considered. A set of relations is developed to describe the asymptotic behavior (for large ion distances) of the ion pair distribution functions. These relations are obtained with benefit only of certain weak, plausible assumptions concerning the triplet superposition defects; as a consequence, the usual superposition approximation of liquid theory is circumvented. A significant feature of the results is prediction of concentric shells of average charge density surrounding a given ion in a manner suggesting local latticelike structure.
Neighbor Interactions and Internal Rotations in Polymer Molecules. IV. Solvent Effect on Internal Rotations
Authors: Lifson Shneior , Oppenheim Irwin
Published: January 2005

Solvent chain-element interactions affect the probability distribution of the angles of internal rotation of a polymer chain and give rise to an average torque on the skeletal bonds of the chain. The average torque and its potential are derived in terms of polymer-solvent interaction potentials and reduced distribution functions. The energy of the polymer molecule, as it was applied in the previous papers of this series, is shown to be the potential of the average torque in the neighbor interaction approximation. This approximation, though insufficient by itself, provides a theoretical basis for the application of the random flight model of polymer molecules and, at the same time, improves upon it by deriving the characteristic parameter of the model (the length of the statistical chain element) as a function of temperature, solvent, and the structural parameters of the polymer chain. Following these considerations, the complementary nature of the theories of neighbor interaction and excluded volume is discussed.
Theory of Singlet-Triplet Splittings in Large Biradicals
Authors: McConnell Harden M.
Published: January 2005

A perturbation calculation is used to estimate small ground-state singlet-triplet splittings in large biradicals in which two triphenylmethyl groups are bridged at para positions by polyene, polyphenylene, polymethylene, or ether groups. The calculated splittings are orders of magnitude larger than the rates of spin exchange reported by Reitz and Weissman for some of these biradicals.
Diffusion in Inhomogeneous Media
Authors: Prager Stephen
Published: January 2005

Methods are given for the calculation of effective diffusion coefficients for inhomogeneous media in which the actual diffusion coefficient varies from point to point in a random manner. An exact result is obtained in the form of an infinite series involving correlations between diffusion coefficients at n different points. A procedure for deriving approximate expressions involving only two-point correlations is also developed, and applied, in particular, to the important special case of diffusion through a porous material.
Molecular Collision Cross Sections from Infrared Absorption Measurements
Authors: Babrov Harold , Ameer George , Benesch William
Published: January 2005

Through measurement of the equivalent width (fractional integrated absorption) of collision-broadened lines of the P branch of the HCl fundamental vibration-rotation band at 3.5 μ, the Lorentz half-widths of these lines have been determined and optical collision cross sections deduced therefrom. The cross sections which have been obtained are those for collisions between HCl molecules and Ar, CO2, CO, D2, H2, HBr, He, Ne, N2, O2, as well as other molecules of HCl. One of the more interesting aspects of these cross sections is their dependence on the rotational state of the absorbing molecule and the various forms which this J dependence takes for the different foreign gases. The line widths range between the extremes of 0.233 and 0.0111 cm—1 atmos—1 while the collision cross sections range between 3.04×10—14 and 0.091×10—14 cm2. Also reported are recently measured values of the strengths for the first eight lines of the P branch of the HCl fundamental. The strength of this band based on these measurements has been found to be 143±5 cm—2 atmos—1 at 300°K.
Excluded Volume Effect of Linear Polymer Molecules
Authors: Kurata Michio , Stockmayer Walter H. , Roig Antonio
Published: January 2005

A new closed expression for the excluded volume effect of linear polymer molecules is developed with the aid of an equivalent ellipsoid model, in which the polymer chain with fixed ends is replaced by a uniform distribution of unconnected segments within an ellipsoid whose dimensions are chosen to give the correct principal radii of gyration of the chain. The linear expansion factor α for a chain of N segments is given by (α3−α)/N12={(1+13α−2)−32}−1(4/3)5/2(3/2π)32(β/a3)where a is the effective bond length and β is the binary cluster integral of a segment pair. In contrast to Flory's familiar equation, the ratio (α5—α3)/N½ is an increasing function of α instead of a constant. The new equation is in excellent agreement with the Monte Carlo calculations of Wall and Erpenbeck for a diamond lattice chain and also with existing viscosity data for various polymer solutions, provided that the expansion factor is evaluated from the equation[η]/[η]θ=α2.43in accord with the theories of Kurata-Yamakawa and Ptitsyn-Eisner. It is also shown that the present equation for α is in rather good agreement with the numerical solution of Fixman's differential equation.
``Forbidden'' Character in Allowed Electronic Transitions
Authors: Albrecht Andreas C.
Published: January 2005

A theory for calculating the intensity of ``forbidden'' character in allowed electronic transitions is given based upon the early work of Herzberg and Teller. It is seen how both symmetric and nontotally symmetric vibrations may be active in the perturbation, and the temperature dependence of ``forbidden'' intensity is explicitly obtained for harmonic oscillator wave functions. As an example the case of certain p-disubstituted benzenes is discussed in detail. A model derivative normal coordinate analysis is used to calculate perturbation energies in terms of electronic wave function parameters. It is seen how the magnitude of ``forbidden'' character is very sensitive to the detailed nature of the mixing electronic wave functions. Several trial functions are introduced to calculate the ratio of ``forbidden'' to allowed character in the near ultraviolet band. Comparison is made with recent observations of mixed polarization in two benzene derivatives. Finally, the possible significance of ``forbidden'' character with respect to radiationless transitions is briefly discussed.
Radiative Lifetime of the B 2Σ+ State in N2O+
Authors: Dayton I. E. , Dalby F. W. , Bennett R. G.
Published: January 2005

The radiative mean lifetime of the upper electronic state (B 2Σ+) giving rise to the 3541 A band of N2O+ has been measured to be τ = (2.6±0.2)×10—7 sec, which corresponds to an oscillator strength f = (3.65±0.28)×10—3. Information about the emission spectrum of N2O+ is also presented.
Flow Adaptation of the Isotopic Dilution Method for the Study of Ionic Hydration
Authors: Baldwin H. W. , Taube H.
Published: January 2005

A method is described for rapid mixing and sampling in the application of the isotopic dilution technique to the study of ionic hydration. The behavior of solutions of various salts has been compared with that of solutions containing a hydrated cation of known formula, namely Cr(H2O)6+ + +. The holdback of water per ion of Al+ + + is the same (within 0.4 molecules of H2O as that of Cr+ + +, and t½ for the exchange of Al(H2O)6+ + + with H2O is >0.02 sec. at 25°·t½ for the exchange of water between Ni+ + (aq) or Fe+ + + (aq) and solvent is less than 0.02 sec.
Dielectric Behavior and Crystal Structure of Ethyl and Vinyl Stearate
Authors: Broadhurst Martin G. , Fitzgerald Edwin R.
Published: January 2005

Measurements of the real (ε′) and imaginary (ε″) components of the complex dielectric constant have been made on ethyl and vinyl stearate and on mixtures of ethyl stearate in n-heneicosane at temperatures from +60° to —80°C and over a frequency range from 100 to 50 000 cps. A relaxation dispersion region, which was similar in shape and position for all samples, occurred below 0°C for the frequency range considered here. The magnitudes of the dispersions were found to be greater the more quickly the samples were frozen, and very much reduced for samples crystallized from acetone. Annealing of the solid samples at temperatures as low as 20 centigrade degrees below the freezing points resulted in a gradual decrease in polarization. Cooling curve data was obtained in order to supplement the above work. The results suggest that the molecular rotations involved in the observed solid state dispersions are associated with metastable crystal structures and that, in particular, the decrease in polarization with time is due to a gradual transformation in parts of the sample from a vertical to a tilted crystal structure.
On the Presence of NaOH in Crystalline NaCl
Authors: Otterson Dumas A.
Published: January 2005

The alkalinity of NaCl crystals from various sources are reported with the method of its determination. Melt-grown crystals are usually more alkaline than natural rock salt. The alkalinity may vary in a melt-grown crystal. The alkalinity appears in melted salt, probably as a result of hydrolysis which produces NaOH and possibly by a reaction capable of liberating chlorine.
Primary Processes in the Gaseous Photolysis of Polyatomic Molecules. I. Biacetyl
Authors: Dubois Jean T.
Published: January 2005

The application of photochemical information to the characterization of primary processes is discussed; the selection of proper experimental conditions is of crucial importance in order to avoid ambiguous or misleading interpretations of such data. As an example, the existing data on the photolysis of biacetyl in the range λ 4358–3660 A is analyzed. The treatment indicates the presence of a single process with an activation energy E=13 300 cal/mole and a frequency factor v=1.5×1013 sec—1.
Near-Infrared Absorption Spectra of Ortho- and Para-H2O in Solid Xenon and Argon
Authors: Glasel Jay A.
Published: January 2005

The near-infrared absorption spectra of H2O trapped in solid argon and xenon have been studied at 20°K. The spectra, taken at concentrations of H2O to matrix of 1:600, exhibit structure which is analyzed in terms of the known rotational and vibrational constants of the H2O molecule. The results show that in solid xenon and argon matrices, the monomer H2O exists as two modifications, one of which is rotating in its ground vibrational state. The theoretical intensities for the spectral bands of H2O gas at 20°K are calculated and shown to agree with the bands observed in H2O-xenon. The changes in the observed intensities for other matrices are discussed. The changes in the spectra of the films when they are warmed to 35°K are shown and discussed.
Frequency Spectrum for a Two-Dimensional Lattice
Authors: Neuberger Jacob , Hatcher Robert D.
Published: January 2005

The methods of lattice dynamics are applied to a study of the frequency distribution function f(v) of a two-dimensional model of a monatomic crystal. It is shown that if the interaction of the atoms of the lattice is of short range such that next-nearest neighbor interactions are much weaker than nearest neighbor interactions, the function f(v) can be expressed in terms of elliptic integrals of the first kind. These functions are calculated for a particular choice of the ratio of the interaction constants which had previously been discussed in the literature by approximate numerical methods. This gives some evidence that the numerical scheme for obtaining f(v), based on a comparatively small spanning of wave-vector space which is used extensively in more complicated crystal models, is adequate provided that v is a fairly smooth function of the wave vector.
Quantum Statistical Mechanical Theory of the Rate of Exchange Chemical Reactions in the Gas Phase
Authors: Yamamoto Tsunenobu
Published: January 2005

A theory of the reaction rate of simple exchange reactions in the gas phase is developed on the basis of the quantum-statistical mechanical theory of linear irreversible processes due to Kubo et al. A formal expression for the rate coefficient is found near the equilibrium point. A number of relations are derived concerning the scattering amplitudes for the collisions involved in the above reactions. By making use of these relations, the rate constant is expressed in terms of the reaction cross sections in a way which coincides with that known from a more intuitive collisional approach. Since no ad hoc assumptions are made, the present theory can be said to provide a statistical mechanical foundation for the collision theory in the particular case discussed.
Thermodynamics, Stationary States, and Steady-Rate Processes. V. A Collection of Corollaries
Authors: Tykodi R. J.
Published: January 2005

A listing is made of a number of direct consequences of the ideas and procedures developed in papers I—IV of the series; the topics considered are reaction equilibria in concentration and in thermal fields, thermocells, steady bithermal mass flow, and compound linkages. Some general remarks about monothermal fields are relegated to an appended section.
Thermodynamics, Stationary States, and Steady-Rate Processes. VI. Forced Vaporization of Selected Liquids
Authors: Erikson Ted A. , Tykodi R. J.
Published: January 2005

The results of forced vaporization experiments are reported for water, carbon tetrachloride, benzene, methanol, and n-butyl alcohol. The data, which were obtained at a monothermal temperature of 25°C and with a tapered tube having available areas from 0.2 to 3.4 sq cm, indicate a linear relationship between the logarithm of the steady pressure maintained above the liquid and the steady mass flow per unit area. A number of complicating features in the experimental arrangement are discussed briefly.
Infrared Studies of Crystal Benzene. II. Relative Intensities
Authors: Swenson Charles A. , Person Willis B.
Published: January 2005

Intensities of the absorption bands observed with a thin sample of polycrystalline benzene have been measured relative to the absorption of v20 at 1036 cm—1. The gas-phase-allowed fundamentals are much the strongest bands in the spectrum. The relative intensities of these fundamentals are considerably different from the relative intensities in the gas or liquid phase. The experimental errors are discussed in detail with the conclusion that the observed difference in relative intensities are well outside any conceivable experimental errors. As a result, it is concluded that existing theories of spectra in condensed phases must be modified to predict different behaviour for each fundamental vibration. Finally, attention is drawn towards some of the anomalies still existing in the assignment of vibrational frequencies in the benzene molecule.
Lattice Vibrations in Alkali Halide Crystals. II. Potassium and Rubidium Halides; Cesium Fluoride
Authors: Karo Arnold M.
Published: January 2005

Vibrational frequency distributions for the potassium and rubidium halides and for cesium fluoride have been evaluated on the basis of the Born lattice theory by the use of Blackman's numerical sampling method. Both room-temperature and extrapolated 0°K parameters have been used in the calculation. Specific heats, the corresponding Debye characteristic temperatures, and the moments of the distributions have been obtained directly from the frequencies. Comparison is made with experimental data and with other theoretical work.
Kinetics of Excited Molecules. II. Dissociation Processes
Authors: Porter Gerald B. , Connelly B. T.
Published: January 2005

A detailed calculation of the rate of dissociation of an electronically and vibrationally excited molecule (photochemical dissociation) is compared with the experimental data for ketene. The results are consistent with unimolecular reaction rate theory. However, the data are not accurate enough to provide unambiguous values for the parameters in the theory.
Nuclear Spin-Lattice Relaxation in Solutions
Authors: Mitchell Richard W. , Eisner Melvin
Published: January 2005

T 1 for protons in C6H5Cl, C6H6, and C6H12 has been measured as a function of concentration in solution with CS2 and CCl4. T1 does not have the dependence on the solution viscosity suggested by the theory of Debye. The rotational relaxation times at infinite dilution are obtained by extrapolation, and the correlation times calculated from these results are compared with the values predicted by the rotating sphere model as well as an inner viscosity and microviscosity model. The inner viscosity model provides the best agreement with the experimental results. The correlation times are found not to be proportional to the volumes of the molecules but seem to be simply related to the moments of inertia as well as the masses of the molecules of interest and the masses of the solvent molecules. An approximate formula which provides good results for the systems above is suggested as τ=2Iηa/μkT, where I is the moment of inertia of the molecule of interest, η is the solvent viscosity, a is the average radius of the molecule, and μ is the reduced mass of the solvent-solute system.
Theorem on Separability of Electron Pairs
Authors: Arai Tadashi
Published: January 2005

The theorem that two functions ΛA(12) and ΛB(12) span subspaces which are mutually perpendicular if the functions are orthogonal to each other in the strong sense; ∫ ΛA*(12)ΛB(13)dτ1=0,is proved here. The theorem is important for the study of chemical bonds.
Isoelectronic Extrapolation of Electron Affinities
Authors: Edlén B.
Published: January 2005

An expression based on theoretical considerations and containing three adjustable constants has been derived for the purpose of extrapolating ionization potentials along isoelectronic sequences. When used to extrapolate electron affinities of the elements of the first and second short period, the formula is found to yield results that are correct within the error limits of the experimental data at present available.
On Inversion of the Linear Laws of Irreversible Thermodynamics
Authors: Helfand Eugene
Published: January 2005

A procedure is developed for inverting the linear laws of irreversible thermodynamics in spite of the singular nature of the admittance matrix when barycentric diffusion currents are employed. The procedure is symmetric in that it is unnecessary to identify one species as a reference solvent. Explicit relations are given for the new coefficients (resistance matrix, heats of transport, Soret thermal conductivity) in terms of the old. Constraints on the new coefficients are also obtained.
Induction Studies in Several Groups of Halogen-Containing Organic Compounds by Their Cl35, Br79, or Br81 Pure Quadrupole Resonance Spectra
Authors: Hooper H. O. , Bray P. J.
Published: January 2005

Induction studies have been carried out in several groups of halogen-containing organic compounds by means of the halogen pure quadrupole spectra. In several straight-chain compounds inductive effects have been examined as a function of the length of the chain in some monohalogenated-paraffin hydrocarbons and as a function of the number of carbon atoms separating halogen atoms attached to either end of dihalogenated-paraffin hydrocarbons. The effects of the hybridization of the carbon atom have also been examined in some aliphatic hydrocarbons. Chlorine pure quadrupole resonance frequencies from chlorine atoms bonded to atoms other than carbon, such as silicon, nitrogen, and sulfur, have been measured, and the effects of these different atoms upon the Cl35 resonance frequencies are qualitatively discussed.

Inductive effects have also been examined in different groups of aromatic compounds. The inductive effect in several chlorobenzyl compounds is found to be about ¾ of what it is in the corresponding chlorobenzene compounds as determined from a comparison of the Cl35 resonance frequencies. Definite discrepancies have been observed between the Cl35 spectra obtained from several aromatic compounds which have molecular structures similar to anthraquinone and the Cl35 frequencies that can be predicted from data obtained from chlorobenzene compounds and Hammett σ values.

Employing the linear relationship between Cl35 resonance frequency and Hammett σ values, several Cl35 frequencies were predicted and compared to the measured frequencies in some chlorobenzene compounds. Some unknown σ values have also been predicted. A linear relationship between Br81 resonance frequencies and Hammett σ values has been developed from measured bromine quadrupole frequencies. Several halogen frequencies from some unrelated compounds have been measured and are tabulated in this paper.
Comparison of the Effects of High Pressure and Low Temperature on the Absorption Spectra of Some Condensed-Ring Aromatics
Authors: Robertson W. W.
Published: January 2005

A comparison of the spectral shifts obtained by lowering the temperature of a solution to those obtained by increasing its hydrostatic pressure shows that the temperature shift is composed of two oppositely directed components. The larger one is the red shift due to solvent density increase with temperature decrease and the accompanying increase in dispersion forces. The second and usually smaller effect is a blue shift that results from a change in the shape of the band as a result of a decrease in the population of the higher vibrational levels with a decrease in temperature.
Osmotic Pressure of Moderately Concentrated Polymer Solutions
Authors: Fixman Marshall
Published: January 2005

By two methods, a linearization and a variational principle, the Born-Green-Kirkwood equation for the radial distribution function is solved approximately and the osmotic pressure of chain polymer solutions computed at arbitrary concentration. The gaussian intermolecular potential energy of Flory and Krigbaum is used, and this restricts the range of validity of the theory to volume fractions less than one-tenth. It is shown how the distribution of polymer molecules in the solvent becomes random as the concentration is increased. For good solvents, the quantity [(P/c2)—RT/Mc], where P is the osmotic pressure and M the molecular weight, is predicted to increase rapidly with concentration c, and then to level off rapidly, the whole effect being accomplished at quite low concentrations as the molecules are forced to overlap. Some experimental corroboration is displayed. Severe doubt is cast on the practicality of the virial expansion of P, and possibly on the validity, beyond quite low concentrations.
Solvent Effects on n→π Transitions in Pyrazine
Authors: Krishna V. G. , Goodman Lionel
Published: January 2005

The T→S and S→S′ spectra of pyrazine and 2,5-dimethylpyrazine in hydrocarbon and EPA glasses has been measured. The S→S′ and S→T spectra of the same compounds in ethanol and isopentane are also reported. When due correction is made for the effect of the rigid media, solvent shifts (from hydrocarbon to EPA) of 60 cm—1 to the red in emission and the same amount to the blue in absorption are obtained for the 0–0 band. The absorption maximum is shifted by approximately 1200 cm—1 to the blue and the emission maximum by about 600 cm—1 to the red. The data is explained in terms of the weak hydrogen bonding and the Franck-Condon strain resulting therefrom. It is suggested that due to the change in the extension of the n orbitals in nitrogen atoms of N heterocyclics, a Franck-Condon destabilization energy results in protonic solvents. The role of the Franck-Condon principle in the n→π* blue shift phenomenon is found to be of considerable importance in accordance with Pimentel's views. The previously reported discrepancy of 500 cm—1 in the 0–0 bands of the T→S emission and S→T absorption of these compounds is entirely explained by media effects.