bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Excess Electron and Hole Band Structures and Carrier Mobility in Naphthalene, Anthracene, and Several Polyphenyls
Authors: Katz Joseph L. , Rice Stuart A. , Choi Sang-il , Jortner Joshua
Published: January 2005

The excess electron and hole band structures of naphthalene, anthracene, and several polyphenyls have been calculated in the tight binding approximation. In addition the anisotropy and the pressure dependence of the mobility tensor has been calculated in the constant-free-time and the constant-free-path approximations. The molecular wavefunctions were represented in the LCAO approximation using Hückel coefficients with the carbon atomic orbitals represented by the best available Hartree—Fock SCF carbon 2p ground-state function involving a linear combination of four Slater-type functions. By this choice of atomic orbitals, we hope to account properly for the behavior of the wavefunction at the large internuclear distances relevant to this problem. All of the above compounds are characterized by a crystal structure containing two molecules per unit cell. There are, therefore, two bands for both the electron and the hole cases. The bandwidths are calculated to be of the order of 0.1 eV. In the a—1 and b—1 directions, the symmetric and antisymmetric bands are degenerate at the zone edge. The electron bands are appreciably split in the c—1 direction.

Although there is no attempt to make absolute calculations of the mobility, the experimental data seem to be in adequate agreement with the scattering models considered. Inferences can be drawn which suggest that further understanding of the mobility will arise from a detailed investigation of the interaction of the charge carriers and the intermolecular and intramolecular vibrations.
Molecular Orbital Study of Nonadditive Substituent Effects
Authors: Martin John S.
Published: January 2005

It is shown that the single-parameter molecular orbital models of substituent perturbations of the benzene ring require that the charge density changes be odd, and the bond orders and polarizabilities be even functions of the perturbation parameters. This behavior excludes the possibility of a cross term in the MO description of those properties of disubstituted benzenes which are proportional to the pi-electron charge densities.
Structure of Isobutylene
Authors: Scharpen LeRoy H. , Laurie Victor W.
Published: January 2005

The microwave spectrum of (CH3)2C=C13H2, CH3C13H3C=CH2, and (CH3)2C=CHD has been studied in the region 8–40 kMc/sec. The effective rotational constants of these species combined with previous microwave data give the structural parameters: rCC(single)=1.507 Å, rCC(double)=1.330 Å, average rCH(methyl)=1.08 Å, rCH(ethylenic)=1.088 Å, average <HCH (methyl)=107°, <HCH (ethylenic)=118.5°, <CCC=115.3°.
Free Energy of Nonequilibrium Polarization Systems. III. Statistical Mechanics of Homogeneous and Electrode Systems
Authors: Marcus R. A.
Published: January 2005

A statistical mechanical treatment is given for homogeneous and electrochemical systems having nonequilibrium dielectric polarization. A relation between the free energy of these systems and those of related equilibrium ones is deduced, having first been derived in Part II by a dielectric continuum treatment. The results can be applied to calculating polar contributions in the theory of electron transfers and in that of shifts of electronic spectra in condensed media. The effect of differences in polarizability (of a light emitting or absorbing molecule in its initial and final electronic states) on the polar term in the shift is included by a detailed statistical analysis, thereby extending Part II. Throughout, the ``particle'' description of the entities contributing to these phenomena is employed, so as to derive the results for rather general potential energy functions.
Kinetics of Desorption. III. Rb+, K+, and Na+ on Rhenium
Authors: Scheer Milton D. , Fine Joseph
Published: January 2005

The mean adsorption lifetimes (τ3) of Rb+, K+, and Na+ ions on a clean polycrystalline rhenium surface have been measured in the millisecond region as a function of temperature under conditions of very low surface coverage. The results of these measurements are given by: Rb+:τ3=(0.8±0.3)×10−13exp[(26 400±350)/T]sec,1000<T<1250∘K;K+:τ3=(1.0±0.3)×10−13exp[(27 000±350)/T]sec,1050<T<1260∘K;Na+:τ3=(0.2±0.1)×10−13exp[(31 900±300)/T]sec,1160<T<1400∘K.

The interaction of the alkali ion with the metal surface was described by a one-dimensional potential function of the form V(x)=l+[1+1n−1(rex)n−nn−1(rex)],where x is the perpendicular distance of the adsorbed ion from the surface and l+ is the observed desorption energy. By choosing the Pauling ionic radius ri as the distance of closest approach to the surface for an ion with energy l+, the parameters n and re were calculated for each alkali ion. It was found that the values of n increase and those of (re—ri) decrease as the atomic number of the alkali ion increases.
Infrared Optical Properties of Cuprous Oxide
Authors: O'Keeffe Michael
Published: January 2005

The transmission and reflection spectra of cuprous oxide have been measured from 2 to 25 μ. The transmission studies included Cu2O18. The isotope shifts help to establish that all the observed infrared bands are due to lattice vibrations and not to defect mechanisms as some authors have suggested. The reflectivity can be treated in terms of a single oscillator dispersion analysis. The derived values of the static and high-frequency dielectric constants are ε8=7.11 and ε0=6.46, respectively.
Lattice Vibrations of LaCl3 and LaBr3 from Vibronic Spectra
Authors: Richman Isaac , Satten Robert A. , Wong Eugene Y.
Published: January 2005

The polarized vibronic spectra of PrCl3 and PrBr3, as well as Pr3+ in LaCl3 and LaBr3, were observed. The theory of vibronic transitions for the dilute salt is shown to predict a spectrum which closely resembles the vibronic spectrum of the pure salt, in agreement with experiment. Approximations valid when the optical vibrational branches of the crystal are flat leading to k=0 selection rules are shown to lead to agreement with the spectra fairly well, although slight violations in selection rules occur and can readily be explained. Tentative identifications of crystalline modes of vibration are assigned partly with the help of polarization data and vibronic selection rules, partly by consideration of frequency shift in comparing the chloride and bromide vibronic spectra, partly from Raman scattering data, and partly with the aid of the far-infrared absorption data of Buchanan, Murphy, and Caspers. The vibronic data in turn help refine the interpretation of the far-infrared results. The difference between longitudinal and transverse vibrating frequencies is discussed.
Significant Structure Theory of Fluids for a System of Rigid Spheres
Authors: Henderson Douglas
Published: January 2005

The basis of the significant structure theory is briefly discussed. It is proposed that the ``solidlike'' degrees of freedom be represented by the Lennard-Jones and Devonshire cell theory partition function rather than the Einstein oscillator position function which has been used previously. The theory is applied to a system of rigid spheres and the pressure and entropy are calculated with good results.
On the Calculation of Some Atomic Integrals Containing Functions of r12, r13, and r23
Authors: Öhrn Yngve , Nordling Jan
Published: January 2005

Different forms of correlated atomic wavefunctions and their implications on the integrals occurring in calculations of variational solution to Schrödinger's equation are briefly discussed. A scheme for computing the integral ∫ f1(r1)f2(r2)f3(r3)g1(r12)g2(r23)g3(r31)(dv)is described and applied to the case gi(rij) = rijk.
Calculation of the Barrier to Internal Rotation in Ethane
Authors: Pitzer Russell M. , Lipscomb William N.
Published: January 2005

Wavefunctions and energies for both the eclipsed and staggered forms of ethane have been calculated in the limited basis set, self-consistent-field approximation. The basis functions are a minimum set of Slater orbitals. All integrals have been evaluated to the necessary accuracy. The calculated value of the barrier to internal rotation is 3.3 kcal/mole in good agreement with experiment. The sensitivity of the value to improvements in the wavefunctions cannot be estimated readily. The bearing of this calculation on proposals of the origin of the barrier is discussed. A transformation to localized molecular orbitals will be necessary for a more detailed discussion of the barrier.
Electric Polarizability of Some Diatomic Molecules
Authors: Kolker H. J. , Karplus M.
Published: January 2005

A variation-perturbation method is employed for the calculation of the electric polarizability tensor of a series of diatomic molecules (H2, Li2, N2, LiH, HF, LiF, CO). The SCF—LCAO—MO functions of Ransil are used as unperturbed solutions and appropriately orthogonalized perturbation functions are introduced to account for the effect of the electric field. For the three molecules (H2, N2, CO) for which experimental data are available, reasonable agreement between the theoretical and the measured values is obtained. However, the calculations appear to somewhat overestimate the electric polarizability, particularly so for the parallel component of the tensor; possible theoretical refinements to reduce this error are discussed.
Near-Infrared Studies of the Structure of Water. I. Pure Water
Authors: Buijs K. , Choppin G. R.
Published: January 2005

The absorption bands of water in the 1.1-to-1.3-μ region have been measured. From the extinction coefficients, concentrations of water species involving 2,1, and 0 hydrogen bonds per molecule were calculated. The temperature dependence of these concentrations yielded a value of 3.7–4.5 kcal for the energy involved in breaking one mole of hydrogen bonds in water. On melting, 46% of the hydrogen bonds originally present in ice are broken; by 72°C the percentage broken has increased to 61. Further, the results were used in conjunction with the flickering cluster model of Frank and Wen to obtain an upper limit for the average size of the water polymers of 90 molecules of H2O at 20°C.
Near-Infrared Studies of the Structure of Water. II. Ionic Solutions
Authors: Choppin G. R. , Buijs K.
Published: January 2005

The infrared absorption bands of water in the 1.1- to 1.3-μ region have been studied. Variations in intensities of three bands have been used to calculate for ionic solutions the mole fractions of water molecules in which zero, one, and two of the hydrogens are involved in hydrogen bonding. The average sizes of water clusters in HCl, HBr, HNO3, HClO4, H2O2, NaOH, KOH, NaNO3, and NaClO4 solutions were calculated. From this and from qualitative evaluations for other solution systems, it was possible to assign the following effect on the water structure to the ions: cations:order−producing: La3+>Mg2+>H+>Ca2+,order−destroying:K+>Na+>Li+>Cs+=Ag+;anions:order−producing:OH−>F−,order−destroying:ClO4−>I−>Br−>NO3−>Cl−>SCN−.
Use of Rescaled Eigenfunctions as Variational Wavefunctions in Calculations on Atoms and Ions
Authors: Ellison Frank O. , Huff Norman T.
Published: January 2005

Electron—electron repulsion energies C̄ and electron—nuclear attraction energies L̄ are computed from the nonrelativistic total energies E for isoelectronic series of two-, three-, and four-electron atoms in their lower electronic states. A limited variational approach to atomic structure is then described which uses in effect rescaled eigenfunctions (for two or more electron systems) as a basis; the ``empirical'' C̄ and L̄ obtained in the first part are employed in these calculations. Use of the eigenfunction for an atom with nucleus of charge Z+1 to predict the energy of an isoelectronic system with nucleus of charge Z yields results which are in error by about 0.3 to 0.7 eV for two- to four-electron atoms, respectively. A semiempirical correction scheme of this approach gives results which are in error by 0.01 to 0.1 eV, respectively. Energies for some states of H, He, and Li negative ions are predicted.
Monte Carlo Calculations for the Two-Dimensional Triangular Lattice Gas: Supercritical Region
Authors: Chesnut Dwayne A.
Published: January 2005

Detailed calculations have been carried out, using a Monte Carlo numerical procedure in a grand canonical ensemble, for the thermodynamic properties of a 10×10 triangular lattice gas model along six isotherms in the supercritical region (reduced temperatures Tr=1.15, 1.20, 1.25, 1.30, 1.35, and 1.40). For each isotherm the thermodynamic properties are given at β(μ—3ε) =0.0, —0.04, —0.20, and —0.40, where μ is the chemical potential and ε is the nearest-neighbor interaction energy. Symmetry relations for calculating all the properties at the corresponding positive values of β(μ—3ε) are also given.
One-Center Perturbation Approach to Molecular Electronic Energies. I. Exposition of the Method
Authors: Hauk Peter , Parr Robert G. , Hameka Hendrik F.
Published: January 2005

A one-center perturbation method for obtaining molecular electronic wavefunctions and energies for hydrides of the type AHn is described. Using the spherically symmetrical component of the nuclear-electronic potential in the molecular electronic Hamiltonian to define a molecular puff, the molecule itself is treated as a perturbed molecular puff by second-order perturbation theory. The resulting Schrödinger perturbation equations are solved in closed form assuming for the puff a one-center determinantal wavefunction of Slater s and p orbitals and neglecting certain coupling terms. Single-integral expressions for the perturbation energies are found, and a particularly simple explicit formula is obtained for the 1s case. The mathematical and physical character of the approximations is discussed, and the practical applicability of the method is appraised.
Iteration-Variation Procedures for Quantum-Mechanical Perturbations
Authors: Hirschfelder Joseph O.
Published: January 2005

The Dalgarno—Lewis procedure is used for obtaining explicit solutions to the perturbation equations. Three basic ideas are exploited: (1) By using the wavefunction through the first order as the zeroth-order wavefunction in a new perturbation calculation, we obtain an iteration procedure that converges with surprising rapidity. After n iterations, the energy is given accurately up to terms of the order of the 2n+1 power of a perturbation parameter. (2) By varying the proportions of the zeroth- and first-order functions in the wavefunction through the first order, we obtain somewhat better energies and still maintain the ability to iterate. (3) For degenerate and almost degenerate energy levels, the wavefunctions through the first order and the energies through the third order are obtained by solving a finite-ordered secular equation. This procedure is much simpler and less apt to fail than the usual techniques.
Radiation-Induced Coloring of Sodium Azide
Authors: Rosenwasser Hyman , Dreyfus Russell W. , Levy Paul W.
Published: January 2005

The coloring of sodium azide (NaN3) by gamma-ray and fast and slow neutron bombardment has been studied by reflection measurements. Gamma rays alone produce a broad absorption band at 3600 A, which is little affected by heating at 90°C, and poorly-defined bands at 6600 A and 7600 A which decay completely at room temperature. Fast neutron irradiation at room temperature, or slow neutron irradiation at 100°C, as well as slow neutron irradiation at room temperature and subsequent heating at approximately 90°C give rise to a band at 6000 A. This also appears when material, which has been subjected to gamma-ray irradiation, is heated at higher temperatures. When heated near the decomposition temperature, the spectra of NaN3 crystals which have been subjected to any of the above forms of irradiation are similar. At this temperature another band appears at 2800 A. Heat treatment alone colors the unirradiated material primarily near 3600 A, but much less intensely than in irradiated crystals. It appears that some of the observed bands are connected with the decomposition of this compound, brought about either by irradiation or thermal treatment.
Rate of Reaction of TNT in Detonation by Direct Pressure Measurements
Authors: Cook Melvin A. , Keyes Robert T.
Published: January 2005

A description of an experimental method of obtaining pressure-time data for the decomposition of coarse TNT following partial detonation is given. This method consisted of photographing (with a streak camera) the displacement of a slug shot from a smooth bore cannon. The velocity and acceleration of the slug were obtained by numerical differentiation of the displacement-time data derived from the photograph. Pressure-time curves were obtained which exhibited pressure maxima at times that were dependent upon the particle size of the TNT detonated in the cannon. Peak pressures for TNT of 4—6 standard mesh particle size occurred between 140—200 μsec, peak pressures for 8—10 mesh occurred between 115—140 μsec, and pressure maxima for ``fine'' TNT occurred between 50—70 μsec. The pressure-time curves were analyzed, and reaction times of the coarse TNT were calculated by two different methods. One method yielded a value of the reaction time for each pressure-time coordinate and the other a reaction time in terms of the time at which maximum pressure occurred. The results obtained by these two methods were not the same. However, when corrections were made for gas leakage from the cannon, rather good agreement resulted. The most probable value computed (after leakage corrections were made) for the 4—6 TNT was found to be about 300 μsec and for the 8—10 TNT about 200 μsec. On the basis of these reaction times the grain erosion velocity for the TNT in the cannon was evidently much greater than linear burning rates at the same pressure obtained experimentally for explosive deflagration.
Mass Spectrometric Study of the B2D6–B5H9 Exchange Reaction
Authors: Koski W. S. , Kaufman Joyce J. , Friedman Lewis , Irsa A. P.
Published: January 2005

The distribution of partially deuterated pentaborane species resulting from the reaction between B2D6–B5H9 and its converse B2H6–B5D9 has been examined mass spectroscopically. It was found that the deuterium is entering the pentaborane by two main processes; namely exchange and synthesis by pyrolysis of diborane. The number of readily exchangeable positions in the pentaborane under our experimental conditions is five. If the remaining four hydrogens are exchanging they are doing so at a very much slower rate. Examination of the mass spectrum indicates that the deuteriums are entering the molecule singly during exchange. Tracer studies with B10 indicate that borons are not involved in the exchange.
Theory of the Electronic Spectra and Structure of the Polyacenes and of Alternant Hydrocarbons
Authors: Pariser Rudolph
Published: January 2005

A previously given theory of the electronic spectra and structure of complex unsaturated molecules is further elucidated by listing specific formulas for the charge density, bond order, transition moment, and configuration interaction matrix elements.

The theory is then applied to give a number of simple rules for alternant hydrocarbons. These refer to the energies of the singly excited states and the effects of configuration interaction, the degeneracy between certain singlet and triplet states, the prohibition of certain electronic transitions which would be allowed from a group theoretical point of view, and the charge density distribution of the ground and singly excited states. A mechanism is proposed to explain some of the anomalously rapid singlet-triplet radiationless transitions which are observed in connection with studies of the lower triplet states of complex molecules.

Quantitative application of the theory is made to the spectra of the polyacenes, benzene through pentacene, and to the bond orders of naphthalene and anthracene, employing a high-speed digital computer. The calculated results are compared with experiment. Some previous assignments of electronic bands are confirmed, and some new assignments are suggested. The location of a number of excited states which have not, as yet, been observed is predicted.
Dynamics of Polymer Molecules in Dilute Solution: Viscoelasticity, Flow Birefringence and Dielectric Loss
Authors: Zimm Bruno H.
Published: January 2005

The problem of the motions of a chain molecule diffusing in a viscous fluid under the influence of external forces or currents is considered for a particular model. This model is a chain of beads connected by ideal springs. Hydrodynamic interaction between the beads is introduced in the approximate form due to Kirkwood and Riseman. It is possible to solve this problem exactly with the use of a transformation to a set of normal coordinates. The viscosity, birefringence of flow, and dielectric and tensile relaxation behavior are calculated explicitly. The intrinsic viscosity in steady flow is somewhat different from the Kirkwood-Riseman result, and there is no change of viscosity with shear rate. The spectrum of relaxation times is similar to that found by Rouse and by F. Bueche, but has its maximum at a lower frequency than those obtained by Kuhn and Kuhn and by Kirkwood and Fuoss in other ways.
Infrared Absorption Studies of Aqueous Complex Ions. II. Cyanide Complexes of Cu (I) in Aqueous Solution
Authors: Penneman Robert A. , Jones Llewellyn H.
Published: January 2005

In the system CuCN–KCN–H2O, we have observed infrared absorption spectra of three distinct complex ions: Cu(CN)2−,ε=165±25 mole−1 liter cm−1 at 2125 cm−1;Cu(CN)3=,ε=1090±10 mole−1 liter cm−1 at 2094 cm−1;andCu(CN)4≡,ε=1657±15 mole−1 liter cm−1 at 2076 cm−1.At 29°C, the constants for the dissociation of Cu(CN)4≡ into Cu(CN)3=+CN— are: K4, 3c = 0.0076±0.0005 mole liter—1 [in terms of concentrations at 0.1—0.2f Cu(I)] and K4, 3a = 0.026 mole liter—1 (in terms of activities). Analogous values for the dissociation of Cu(CN)3= into Cu(CN)2—+CN— are K3, 2c = (2.44±0.36)×10—5 mole liter—1, and K3, 2a = 4.2×10—5. The above values are calculated from approximately 100 determinations. At 25°C, the corresponding values of these constants are approximately K4, 3c = 0.0057 and K3, 2c = 1.5×10—5.

Using the activity constants determined in this paper and a value of 1×10—24 for the constant: [Cu+][CN—]2/[Cu(CN)2—] we derive the following values: [Cu+][CN—]3/[Cu(CN)3=] = 2.6×10—29 and [Cu+][CN—]4/[Cu(CN)4≡] = 5×10—31. The free energies of formation of the complex ions are thus: Cu(CN)2—, ΔFf0 = 58.5 kcal/mole; Cu(CN)3=, ΔFf0 = 91.8 kcal/mole; and Cu(CN)4≡, ΔFf0 = 129 kcal/mole.
Infrared Spectra of Crystalline Symtetrabromo and Tetrachloroethane
Authors: Kagarise R. E.
Published: January 2005

The infrared spectra of liquid and crystalline CHBr2CHBr2 and CHCl2CHCl2 have been obtained in the 2 to 36μ region. It has been observed that CHBr2CHBr2 will crystallize as either trans-or gauche molecules, depending upon the method of cooling employed. To date, crystalline CHCl2CHCl2 has been prepared in the gauche-form only. On the basis of these data and previously reported Raman spectra, a partial assignment of the fundamental frequencies has been made.
Chain Model for Polyelectrolytes. III. Equimolar Polyampholytes of Regularly Alternating Structure
Authors: Rice Stuart A. , Harris Frank E.
Published: January 2005

The chain model for polyelectrolytes developed in the preceding papers of this series is extended to polyampholytes composed of a regular alternation of acidic and basic groups. Included in this model are the effects of counter ion binding, dissociation equilibria among the acidic and basic groups, and electrostatic interactions among the charges of the polymer. The electrostatic free energy of interaction between neighboring charges of the chain was computed including interactions between both nearest and next nearest neighboring charge sites by a simple extension of the methods previously employed. The equilibrium conditions are then expressible as a set of simultaneous equations which may be solved by a convenient iterative method.

The end-to-end extension may be calculated by previously described methods except in the vicinity of the isoelectric point (i.p.), near which point the effects of charge fluctuations become relatively more important. It is shown how both charge fluctuation and the distribution of monomer units along the polymer chain are related to its end-to-end extension. However, for a regularly alternating copolymer the skeletal distribution effect vanishes.

Calculations for a hypothetical polymer indicate that the expansion is nearly independent of ionic strength, and that the fluctuations produce a negligibly small contraction at the i.p. However, it is found that added salt acts, primarily by reducing the electrostatic forces, to alter the titration curves in the same manner as has been observed experimentally in dilute protein solutions.
Infrared Spectrum of Gaseous Aluminum Chloride
Authors: Klemperer William
Published: January 2005

The infrared spectra of gaseous Al2Cl7 and AlCl3 have been studied from 1200 to 325 cm—1. Bands of Al2Cl6 have been observed at 625, 484, 420 cm—1. One band of AlCl3 at 610 cm—1 has been observed. A calculation of the force constants of these molecules is made. The methods used to obtain the spectra appear suitable for the study of substances which are volatile at high temperatures.
Calculation of Depolarization Factors of the Raman Lines of CBr3X Molecules
Authors: Krupp Robert H. , Ferigle Salvador M. , Weber Alfons
Published: January 2005

The depolarization factors of CBr3H and CBr3Cl have been measured by techniques described in the literature and the depolarization factors of the totally symmetric vibrations of CBr3H, CBr3D, and CBr3Cl have been computed using expressions for the spur and anisotropy of the polarizability tensor given previously. The associated normal coordinate treatment uses the Wilson FG-matrix technique. Calculated and observed depolarization factors agree well for stretching but not for the bending modes, as has been shown to be the case in similar molecules.
On the Free Energy of Solutions
Authors: Rice Stuart A.
Published: January 2005

The proposal has been made that the free energy of a mixture is (aside from the free energy of mixing) equal to the sum of the free energies of the pure components computed at a reduced temperature and reduced volume characteristic of the environment of the molecules in the solution. This proposal is tested for a simple model, the generalized cell model for solutions, and found to be a good approximation.
Spectroscopic Properties of Organic Photoconductors. I. Absorption Spectra of Cationic Dye Films
Authors: Weigl John W.
Published: January 2005

The absorption spectra of solid films of six photoconductive dyes are reported. The transitions in the solid state correspond to those of the ``isolated'' cations in solution. However, the longest-wavelength singlet-singlet absorption band is split into components separated by 1000 cm—1 or more. Other bands are unaffected, except for a general decrease of oscillator strength. The results are interpreted in terms of light absorption by a single molecule, followed by exciton motion in the lowest excited state.
Infrared Spectra of Some Deuterated Silanes
Authors: Meal Janet Hawkins , Wilson M. Kent
Published: January 2005

The infrared spectra of SiD4, SiHD3, and SiH2D2 have been observed in the region 2—16 microns. Values of ζ obtained for the 851 cm—1 band of SiHD3 and the 1597 cm—1 band of SiD4 are 0.76 and 0.10, respectively. Assignments are given for the observed bands and force constants are calculated.
Use of Punched Card Machines for Computing Sums of Products. The Application to Electron Diffraction Calculations
Authors: Bregman Judith
Published: January 2005

A punched card procedure for computing sums of products is described. It requires only a small card file and machines that may be available in IBM installations not set up primarily for scientific computation. The application to electron diffraction calculations is described.
Vibrational Spectra of Fluorinated Aromatics. XI. o-Fluorochlorobenzene
Authors: Narasimham N. A. , Nielsen J. Rud
Published: January 2005

The infrared absorption spectra of gaseous and liquid o-fluorochlorobenzene have been obtained in the region 2—38μ with NaCl and CsBr prisms. The Raman spectrum of the liquid has been photographed with a 3-prism glass spectrograph of linear dispersion 15 A/mm at 4358 A. A complete assignment of the fundamental vibrational frequencies is given, and the spectra are interpreted in detail.
On the Computation of Auxiliary Functions for Two-Center Integrals by Means of a High-Speed Computer
Authors: Corbató F. J.
Published: January 2005

With the view of computing simple two-center integrals by means of a high-speed computer, programs for certain basic auxiliary functions, which are essentially the usual An(y) and Bn(x), have been prepared. Computational procedures for generating these functions are given.
Calculation of Intermolecular Force Constants from Polarizabilities
Authors: Brandt Werner
Published: January 2005

Two quantum mechanical approximation formulas due to Slater and Kirkwood are modified empirically such as to relate the empirical intermolecular force constants of a two-parameter potential to the average polarizabilities and the number of valence electrons of the interacting molecules. Their usefulness is demonstrated in predicting the force constants of the Lennard-Jones (12—6) potential of fourteen nonpolar gas molecules and of one polyatomic group in a polymeric chain molecule. The limited applicability of the modified Slater-Kirkwood formulas to dipolar and/or nonspherically symmetric molecules is discussed.
Statistical Thermodynamics of Solutions
Authors: Prigogine I. , Bellemans A. , Englert-Chwoles A.
Published: January 2005

A new approach to the statistical problem of solutions is presented, which combines the main ideas of the cell method and of the theorem of corresponding states. The basic assumption is that the cell partition function of a molecule in the solution may be formally expressed by the same function as in pure liquid, but with other well-defined values of the reduced temperature and volume.

For pure liquids this theory reduces to the usual theorem of corresponding states. The excess properties of the mixture are expressed in terms of molecular parameters related to the interaction energies between pairs of molecules. All the macroscopic coefficients appearing in the excess functions are expressed by experimental properties of the pure compounds, just as in the theory of conformal solutions of Longuet-Higgins. The present model correctly gives the ``first-order contributions'' to the excess functions like the theory of conformal solutions; it gives also an approximative estimate of the higher order terms. Explicit expressions for the excess functions have been calculated up to the second-order terms. The relations between intermolecular forces and excess functions is discussed in detail for some typical cases.

All the conclusions drawn from this model confirm those obtained previously by Prigogine and his collaborators; however the present model permits a much more direct derivation of the main results without the introduction of subsidiary simplifying hypotheses (like simplified cell models).
Emission Spectra of Nitrogen in the Vacuum Ultraviolet
Authors: Wilkinson P. G. , Houk N. B.
Published: January 2005

The emission spectra of nitrogen have been photographed in the vacuum ultraviolet under high resolution. Selected bands of the b′1Σu+—X1Σg+ and the a1Πg—X1Σg+ systems have been analyzed and new rotational and vibrational constants obtained. The observed Λ-type doubling of the a1Πg state was used to determine that the Fc′ doublet component lies above the Fd′ component. Rotational perturbations were found in the v=0 level of the a1Πg state, and in the v=0 and 1 levels of the b′1Σu+ state. Vibrational perturbations were found in the v=4, 5, and 6 levels of the b′1Σu+ state and a new predissociation at v=4, J=9 was observed. The new predissociation limit lies at 13.233 ev and is equally compatible with either the 9.756 ev or the 7.373 ev ground-state dissociation energy.
Effect of Hydrogen Bonding on the Deformation Frequencies of the Hydroxyl Group in Alcohols
Authors: Stuart A. V. , Sutherland G. B. B. M.
Published: January 2005

The effects of hydrogen bonding on the infrared spectra of aliphatic alcohols have been studied in the range 4000 to 350 cm—1. Twenty-six alcohols were investigated of which 10 were primary, 7 were branched primary, 6 were secondary, and 3 were tertiary. Attention was concentrated on the region of the spectrum between 1500 cm—1 and 350 cm—1 where the deformation vibrations of the OH group occur. Spectra were obtained of the alcohols (a) in dilute solution in nonpolar solvents, (b) in the liquid state, and (c) in the vapor state, the degree of association being followed by observation of the well-known effect of hydrogen bonding in the OH stretching vibration near 3.0μ. Methanol, ethanol, and hexanol-1 were also investigated after deuteration of the OH group. All the alcohols exhibited a broad diffuse association band with a maximum near 650 cm—1. This has been assigned to the out-of-plane deformation vibration of the H atom in the COH group. All the alcohols also exhibited a broad association band which usually had 2 maxima near 1410 cm—1 and 1330 cm—1. This band (which appears to have been missed by previous workers) is assigned to the in-plane deformation vibration of the H atom in the COH group. The corresponding monomeric band varies between 1200 cm—1 and 1330 cm—1 in undeuterated alcohols and between 870 cm—1 and 930 cm—1 in deuterated alcohols. There is in addition a very narrow association band which lies near 1100 cm—1 in primary and secondary alcohols and near 1165 cm—1 in tertiary alcohols. This is assigned to the effect of hydrogen bonding on the skeletal vibrations, which involve stretching of the CO bond. It appears that the effects of hydrogen bonding on the deformation motions of the OH group are quite complex and that steric effects, rotational isomerism, and interaction with C – H deformation frequencies may all be involved to some extent.
Lowest Triplet State of Anthracene
Authors: Padhye Madhu R. , McGlynn Sean P. , Kasha Michael
Published: January 2005

A study has been made of the electronic transitions between the lowest triplet state of anthracene and its ground state. Low-temperature spectroscopic study of the phosphorescence revealed a sharp emission band with a 0,0-frequency (T→S) at 14 927 cm—1 (EPA rigid glass solution at 77°K). A vibrational analysis in terms of known Raman frequencies indicates that the transition is of a u→g allowed type. The T←S absorption band was observed in anthracene with the 0,0-frequency at 14 850 cm—1 (solution at 293°K). The study of the phosphorescence spectra of seven different chlorinated anthracenes confirmed the assignment of the anthracene lowest triplet. This study re-establishes the earlier value obtained by Lewis and Kasha, and rejects the recent value deduced by Reid. A correlation of the above results for anthracene with calculations and observations on related polyacenes indicates that the lowest triplet of benzene is 3B1u (in D6h), and for naphthalene, anthracene, and naphthacene the lowest triplet is 3B2u (in D2h). The perturbing singlets which mix with these triplets are obtained from previously derived rules for spin-orbital coupling in molecules.
Proton-Deuteron Hyperfine Structure in Paramagnetic Resonance: A π-δ Interaction
Authors: Venkataraman Balu , Fraenkel George K.
Published: January 2005

The mechanism of the hyperfine splitting observed in paramagnetic resonance spectra of certain aromatic free radicals containing protons adjacent to the aromatic ring is examined. It is shown that the magnitude of the interaction between an unpaired electron in a π orbital and a vibrating hydrogen atom is insufficient to account for the observed splitting. Such a vibrational mechanism is considered to be untenable: (i) on the basis of quantitative calculations, (ii) by the failure to observe lines corresponding to the first excited vibrational state, and (iii) by a comparison of the splitting caused by protons and deuterons. It is suggested that the unpaired electron is not in a purely π state and that the splitting may be accounted for by configuration interaction between π and δ states.
Kinetic Study of the Reaction of Diborane with Phosphine
Authors: Brumberger H. , Marcus R. A.
Published: January 2005

The homogeneous gas phase reaction between diborane and phosphine at 0°C, yielding a solid product of composition BH3PH3, has been observed to give a linear relation between the initial rate of reaction and the pressure of either reactant, provided a certain pressure of each reactant, determined by the equilibrium constant and the pressure of the other gas, is exceeded. The reaction rate is independent of the amount of surface of the solid product or of the wall. When either reagent is in appreciable excess, the rate-time data obey a pseudo first-order equation.

These facts are consistent with a rate-controlling reaction of diborane with phosphine to give BH3PH3 and BH3, the borine reacting further with phosphine, and the BH3PH3 condensing rapidly to a solid. This mechanism leads to a rate equation which is in good agreement with the experimental evidence. The activation energy of the rate-controlling step is 11.4±2.0 kcal mole—1.
Spectrophotometric Study of the Liquid-Phase Equilibrium N2O4⇌2NO2 in Pure Nitrogen Tetroxide
Authors: Steese C. M. , Whittaker A. Greenville
Published: January 2005

The liquid-phase equilibrium constants for the reaction N2O4⇌2NO2 in pure nitrogen tetroxide were measured over the normal liquid range of the substance. The NO2 concentration in the liquid was determined by comparing its light absorption in the liquid with the absorption of a known concentration in the vapor. The results gave a linear relation between log equilibrium constant, and the reciprocal of the absolute temperature. An average heat of dissociation of N2O4 in the liquid phase of 19.5 kcal/mole was obtained.
Microwave Absorption and Molecular Structure in Liquids. XII. Critical Wavelengths and Intermolecular Forces in the Tetrahalogenated Methanes
Authors: Miller Robert C. , Smyth Charles P.
Published: January 2005

The dielectric constants and losses of bromotrichloromethane, dibromodichloromethane, tribromochloromethane, dibromodifluoromethane, tribromofluoromethane, and trichlorofluoromethane, and of two solutions of trichlorofluoromethane in carbon tetrachloride have been measured at wavelengths of 1.24, 3.22, and 10.0 cm at temperatures between 0 and 60°. The arc plots constructed from these data and the measured static dielectric constants have been used to obtain the optical dielectric constants and the critical wavelengths at which the loss is a maximum. The optical and the static dielectric constants have been used to calculate, by means of the Onsager equation, the values of the small molecular dipole moments, which are in excellent agreement with such values as have been previously determined from vapor measurements. For five of the six molecules studied, the critical wavelengths, which are proportional to the molecular relaxation times for these liquids of low dielectric constant, are roughly consistent with the intermolecular attractive forces as evidenced by the boiling points, polarizabilities, and viscosities of the liquids. The departure of the tribromofluoromethane molecule from spherical form is sufficiently great to account for its larger critical wavelength. The internal or microscopic viscosities hindering molecular rotation in the liquids are much smaller than the measured macroscopic viscosities.
Kinetics of Activation Controlled Consecutive Electrochemical Reactions: Anodic Evolution of Oxygen
Authors: Bockris J. O'M.
Published: January 2005

The kinetics of activation controlled electrode reactions differ from those of chemical kinetics by the potential dependence of the rate constant of a step involving charge transfer and the constancy of concentration of reactants in the initial state. A method is proposed whereby an expression for the kinetics of an electrode reaction containing any number of intermediate steps may be obtained.

The method is applied to five paths for the electrolytic evolution of oxygen at anodes and yields limiting expressions for the dependence of the current density (or rate) of the reaction upon electrode potential which are diagnostic of the various rate controlling steps assumed. If discharge of OH′ or H2O molecules is rate determining, the Tafel slope is 2RT/F at overpotentials > 50 mv. If some other reaction involving charge transfer is rate determining, two possible Tafel slopes, each independent of potential in its range of applicability, occur, depending upon degree of coverage of the electrode with intermediate products. If a reaction involving no charge transfer is rate determining, a number of Tafel slopes is indicated, each characteristic of the rate controlling reaction, and an activation controlled limiting current density is possible.

Quantitative conditions for change of mechanism with current density are evaluated. For the initial reaction of a consecutive series to be rate determining it suffices that the rate constant for the backward partial reaction of this step be limitingly small compared with other rate constants in the series; for the last reaction to be rate controlling, the rate constant of its forward partial reaction must be limitingly small; for any other reaction in the series, both backward and forward rate constants of the rate determining reaction must be limitingly small.

The rate of the anodic oxygen evolution reaction as a function of pH is evaluated, taking into account concentration and foreign electrolyte effects on the electrokinetic potential at the electrode-solution interface. The results enable the discharging entity in solution to be distinguished.

Former data are reinterpreted from the criteria of mechanism deduced.
Stretching Force Constant of the Carbonyl Bond in Unconjugated Ketones
Authors: Halford J. O.
Published: January 2005

The secular equation derived for the normal frequencies of a Y-shaped C2CO model can be used with fair accuracy to obtain the carbonyl bond force constant from the measured carbonyl frequency of any symmetrical ketone if the carbon-carbon force constant and the bond angles are known or can be reasonably assigned.

The narrow spread of carbonyl frequencies observed for unconjugated ketones, with assumed ``normal'' angles and carbon-carbon force constant, indicates a nearly constant carbonyl stretching force constant in the range 10.2±0.3 (×105 dynes/cm). This value should be equally reliable for unsymmetrical unconjugated ketones.

In formaldehyde, the calculated force constant is usually above 12.5 units.
Flame Propagation : The Random Walk of Chemical Energy
Authors: Eyring Henry , Giddings J. Calvin , Tensmeyer Lowell G.
Published: January 2005

A new approach to the theory of burning velocity is presented in which a flame front moves forward at a rate determined by the random walk of chemical (potential) energy. The flame velocity is determined by the value of n which is a collision rate divided by a reaction rate, both determined at the point of maximum reaction velocity. The comparison between theoretical and experimental flame velocities is given for cases in which the chemical kinetics are quite well understood. Empirical activation energies for reaction are given for certain hydrocarbon flames. It is hoped that these may be useful in determining the important chemical processes in hydrocarbon flame propagation.
Spectroscopic Properties of Organic Photoconductors. III. Action Spectra for the Photoconduction of Cationic Dye Films
Authors: Weigl John W.
Published: January 2005

The action spectra for photoconduction in solid films of four cationic dyes have been measured. Both the response and the quantum yield curves have maxima at the main absorption peaks, which correspond to the singlet-singlet transitions of the dye cations. The maximum efficiency of carrier production in rhodamine B is of the order of 0.1 electron excited per quantum absorbed.
Chemical Reactions with White and Gray Tin
Authors: Gela Theodore
Published: January 2005

Each of the two polymorphic forms of pure tin were found to produce different chemical compounds when reacted with concentrated hydrochloric acid under identical conditions. These findings were established by x-ray diffraction and chemical analysis. The metallic form of β white tin combined as Sn++, whereas the semiconducting form of α gray tin combined as Sn++++. This chemical behavior was found to be consistent with the electronic configuration of the valence electrons ascribed to each form of the tin atom.
Thermal Expansion and Stability of Layer Structures in Ionic AB Compounds
Authors: Bredig M. A.
Published: January 2005

Thermal expansion in PbO, SnO, or LiOH, in which single layers of O2— or Li+ alternate with double layers of Pb2+, Sn2+, or (OH)—, respectively, is relatively small normal to the layers (c-axis). This ``anomaly'' is related to asymmetrical dilatation of the polarizable Pb2+, Sn2+ in the field of O2— anions, or, respectively, to elongation of (OH)— in the field of Li+: When the cation-anion distance increases with temperature, the resulting decrease in these deformations reduces the spacing between the layers of like polarizable ions and the effective thermal expansion. Structures of this type are not stable for AB compounds if the polarized ion is the anion, but are if it is the cation: As cation polarizability increases with polarization, asymmetric, one-sided coordination of polarizing anions occurs, the energy being further lowered by dispersion forces acting between dilated cations. On the contrary, anions tightened by cations approach the behavior of rigid ions in coordinating cations more symmetrically in three-, rather than two-dimensional networks.
On the Question of the Correct Values for Rayleigh's Ratio
Authors: Carpenter D. K. , Krigbaum W. R.
Published: January 2005

Rayleigh's ratio values for benzene, toluene, and a toluene solution of the Cornell polystyrene were determined by absolute transverse scattering measurements. Use of a diffuser in the determination of the intensity of the primary beam is superior to direct measurement from the point of view of both random and systematic errors. Both these absolute measurements, and relative measurements on two polystyrene fractions of known number-average molecular weight, confirm the ``high'' absolute scattering values. There exists a second set of absolute values, some recently determined, which is 40% lower. Likely sources of error in these measurements are pointed out.