bluuebunny/crossref_metadata_2025 huggingface dataset:
Temperature Dependence of Sound Dispersion in Halo-Methane Gases
Authors: Amme Robert , Legvold Sam
Published: January 2005

Sound dispersion has been examined in eight halo-methane gases near 100°C and 200°C, and four near 300°C. The observed relaxation times have been used along with data obtained previously at room temperature to calculate the vibrational collision lifetimes over this temperature range. The results have been compared with theoretical predictionsof Schwartz and Herzfeld which used an attractive term in the potential to help account for the effect of long-range forces. Agreement is good, although several lifetimes at room temperature appear somewhat small.
Electronic Distribution in Some Conjugated Ketones. Molecular Orbital Calculations Including Overlap
Authors: Payette Gisele , Sandorfy C.
Published: January 2005

Electronic charge distributions in 8 conjugated ketones were computed by the semiempirical molecular orbital method in Wheland's approximation, including overlap between adjacent atoms. It is found that inclusion of overlap leads to a clearer picture of charge distribution. It is shown that covalent and ionic contributions to bond energies may decrease or increase at the same time upon excitation, or a structural change in the π system.

A new ``Coulombic bond order'' is defined, giving a measure of bond energies in terms of Coulombic interactions between local charges.
Semiempirical Treatment of the Hydrogen Bond
Authors: Reid C.
Published: January 2005

A semiempirical treatment of the hydrogen bond based on a slightly modified Lippincott-Schroeder potential has been used to construct potential surfaces for simultaneous hydrogen and oxygen motion in OH···O hydrogen bonds. The resulting potential curves have been used to interpret the changes in infrared spectra and in lattice dimensions in H-bonded crystals on deuteration. The ferroelectricity of KH2PO4 is also discussed.
Static Space-Charge Distributions with a Single Mobile Charge Carrier
Authors: Proctor T. M. , Sutton Paul M.
Published: January 2005

The static space-charge distributions are found when only one mobile charge carrier exists between plane parallel blocking electrodes. The carriers are assumed to move under diffusion and conduction (Debye-Hückel). Charge dissociation (production) is assumed to be proportional to the combined (bound) charge concentration, which depends on location, where previous two-carrier theory assumes charge dissociation is everywhere a constant. Charge distributions are shown to depend strongly on the recombination rate/dissociation rate ratio and the differences from the symmetric two-carrier cases are discussed. Curves of ln concentration (or voltage) vs distance are given for several applied voltages, recombination rate/dissociation rate ratios, and sample lengths, including the semi-infinite case.
One-Dimensional Inelastic Collisions with Impulsive Interactions
Authors: Widom B.
Published: January 2005

A linear oscillator interacting impulsively with a free particle incident along its line of oscillation will in general suffer a change in state; and this model may be taken to represent an inelastic molecular collision. It is pointed out that this picture is substantially equivalent to that used by Castellan and Hulburt, with one modification. The problem is formulated for both quantum and classical mechanics. Explicit transition probabilities are calculated for two extreme cases: (i) the mass and momentum of the incident particle are small, while its energy is fixed; (ii) the mass of the incident particle is small and its energy is large, while its momentum is fixed. The quantum form of approximation (i) is essentially the approximate theory of Castellan and Hulburt. In the present paper the emphasis is on approximation (ii), for which it is shown that in both the classical and quantum theories the average energy transferred to an oscillator of mass m by an incident particle of momentum p is 2p2/m, whatever the law of force of the oscillator and whatever its initial state. It is also shown in this approximation that the classical transition probability for the harmonic oscillator may be recast in a pseudoquantum form so as to allow direct comparison with the quantum mechanical transition probability over the whole range of momenta of the incident particle.
Limitations of the Reflected Shock Technique for Studying Fast Chemical Reactions and Its Application to the Observation of Relaxation in Nitrogen and Oxygen
Authors: Strehlow Roger A. , Cohen Arthur
Published: January 2005

Strip film and multiple spark schlieren pictures of reflected shocks were taken in the gases He, A, N2, O2, H2, NO, CO2, N2O, CH4, and C3H8. Interaction of the reflected shock with the boundary layer behind the incident shock was observed in all gases except He and A. The bifurcation and acceleration associated with the interaction limits the use of the reflected shock region for high-temperature kinetic and equilibrium studies. It was possible to minimize the effects of this interaction by using gases with high γ and confining measurements to a region near the back wall. Reflected shock observations agreed with Mark's theory of the development of bifurcation but disagreed with his predicted deceleration of the reflected shock.

From comparison of incident and reflected shock velocities, measured at the backwall, with ideal one-dimensional theory, it was concluded that calculations of the temperature behind the reflected shock from incident shock velocities would yield high results.

Decelerations of the reflected shock in N2 and O2 have been observed in the strip films and were related to the vibrational relaxation behind the reflected shock. Measurements of relaxation times from the film yielded values which are in good agreement with Blackman's data. These experiments indicate that changes in reflected shock velocity can be used to observe the overall reaction rates of fast chemical reactions.
Heats of Dimerization of Alkali Fluoride Molecules
Authors: Schoonmaker Richard C. , Porter Richard F.
Published: January 2005

A mass spectrometer has been used to analyze vapors in equilibrium with alkali fluoride condensed phases. Monomers, dimers, and trimers have been detected in all alkali fluoride vapors. In addition to monomers and dimers characteristic of pure condensed phases, mixed dimers were found in equilibrium with mixed condensed phases. A method for determining the difference in dimerization energies for constituents in a mixed vapor has been formulated, and dimerization enthalpies for alkali fluoride species are presented.
Polymers and Theory of Numbers. III. Some Remarks on the Theories of Random Degradation
Authors: Nanda V. S. , Pathria R. K.
Published: January 2005

The number-theory technique employed by the authors in the development of a new formulation of the problem of degradation of polymers is used here to resolve an important discrepancy that exists between the results obtained from the probability approach and results from a different approach used by Tuckett. Some of the other conclusions arrived at by Tuckett are also subjected to a critical examination.
Microwave Spectra of Molecules Exhibiting Internal Rotation. V. Barrier Height in Ethyl Chloride and Ethyl Bromide
Authors: Lide David R.
Published: January 2005

The barriers to internal rotation in C2H5Cl and C2H5Br have been determined from the splittings of microwave lines in the first excited torsional state. The values obtained are V0=3560±12 cal/mole for C2H5Cl and V0=3567±30 cal/mole for C2H5Br. The influence of nuclear quadrupole hyperfine structure on the torsional splittings is discussed.
Paramagnetic Resonance Study of Irradiated Glasses of Methanol and Ethanol
Authors: Zeldes Henry , Livingston Ralph
Published: January 2005

Methanol and ethanol, including some of those alcohols with deuterium substitution, have been cooled to glasses at 77°K, irradiated with gamma rays, and then examined at several temperatures in a paramagnetic resonance spectrometer. The alcohols become intensely colored and a paramagnetic resonance spectrum associated with this color has been observed superimposed on part of an underlying spectrum. The color can be bleached with incandescent illumination, and after bleaching the underlying three- or five-line spectrum (methanol and ethanol, respectively) becomes stronger showing that the bleachable species is a precursor for at least a portion of the species giving the underlying spectrum. The manner in which the five-line ethanol spectrum changes with temperature is discussed. Deuterium substitution shows that the hyperfine lines originate from four of the protons originally present on the carbon atoms of the parent alcohol and that a proton of the parent alcohol has left the α-carbon. Possible radicals that could explain the results are discussed.
Infrared Spectra of H2O, D2O, and HDO in Solid Argon, Krypton, and Xenon
Authors: Catalano Edward , Milligan Dolphus E.
Published: January 2005

Infrared spectra of H2O and D2O suspended in solid argon, zenon, and krypton have been obtained in the temperature range 20–4.2°K. A systematic study of the spectra of these species as a function of concentration and temperature has been carried out. Doublets with components centered within a few wave numbers of the gas phase OH and OD stretching frequencies are observed at dilutions in the range 500–1300 for the quantity M/R (M/R denotes molar ratio of rare gas to H2O or D2O). Spectra of these species in the bending region are considerably more complex. Between six and eight bands with frequency separations on the order of 10–20 cm—1 are observed in this region. These features appear to be independent of M/R in the range 500–1300. At least one and possibly two of the lower frequency components in the spectrum of H2O in argon decrease in intensity on lowering the temperature of the sample. These results have been interpreted on the basis that H2O and D2O rotate in solid Ar, Xe, and Kr.
Proton Magnetic Resonance in Polyisobutylene at Various Temperatures, Pressures, and Frequencies
Authors: Nolle A. W. , Billings J. J.
Published: January 2005

New experimental data are reported for the effects of pressures up to 1060 kg/cm2 on the hydrogen nuclear magnetic resonance line width for polyisobutylene, at various temperatures from — 100°C to 32°C. The spin-lattice relaxation time is measured at room temperature for frequencies from 1.9 to 39 mc, in which range it varies approximately as the first power of the frequency, and is also investigated as a function of pressure at fixed frequency. Pressure effects on the line width are discussed in terms of an activation energy dependent on the volume. The frequency dependence of the relaxation time indicates, but does not completely determine, a distribution of thermal motion correlation times. The effects of three hypothetical distributions are computed.
Effect of Ring Size on the Far Ultraviolet Absorption and Photolysis of Cyclic Ethers
Authors: Fleming Gretchen , Anderson Mary M. , Harrison Anna J. , Pickett Lucy W.
Published: January 2005

Absorption curves, tabulated extinction coefficients, and oscillator strengths are given for trimethylene oxide, ethylene oxide, and formaldehyde vapor in the spectral range 2000–1550 A. A comparison is made of the spectra and photochemical stability of these compounds with those of previously determined five- and six-membered ring ethers.
Kinetics and Molecular Weight Distributions for Unsteady-State Polymerizations Involving Termination by Chain Transfer with the Monomer
Authors: Kyner W. T. , Radok J. R. M. , Wales M.
Published: January 2005

The formal unsteady-state kinetics of a polymerization reaction with first-order initiation and termination by chain transfer with the monomer are solved, and expressions are obtained for number and weight average degrees of polymerization and polymerization rate as a function of time. L. Gold's results for the case of no termination are included as a special case. The qualitative description of the kinetics by a single partial differential equation is also outlined.
Nuclear Magnetic Shielding Constants for Several 2-, 3-, and 4-Electron Atoms and Ions
Authors: Ormand Fred T. , Matsen F. A.
Published: January 2005

Nuclear magnetic shielding constants have been calculated for H—, He, Li+, Be++, Li, Be+, and Be using both open- and closed-configuration wave functions with optimized orbital exponents. The accuracy of the values reported is supported by the close agreement between the values obtained for He, σ=5.9856×10—5 and σ=5.9913×10—5, respectively, and that obtained by Hylleraas and Skavlem using the first five terms of the Hylleraas wave function, σ=5.9938×10—5.
Study of the Wurtzite-Type Binary Compounds. III. Valence Band Structure of BeO
Authors: O'Sullivan W.
Published: January 2005

The LCAO approximation is applied toward a description of the valence band in BeO, in which only the closed shell Be(1s)2O(2p)6 configuration is considered. Thus no account is taken of the deformation of the oxygen valence electron distribution by the polarization field along the c axis of the wurtzite-type crystal. The problem is solved along several lines of symmetry in the hexagonal brillouin zone. We find a band width of 18 ev with a depth of approximately 7 ev.
Generalization of the One-Dimensional Ising Model Applicable to Helix Transitions in Nucleic Acids and Proteins
Authors: Hill Terrell L.
Published: January 2005

The exact treatment of the Ising model for an infinite, one-dimensional system has been generalized to make it applicable to the helix transition in synthetic polynucleotides, DNA, synthetic polypeptides, and proteins. The particular advantages of the present treatment are flexibility and generality: the free energies of sequences of similar units of any size can be assigned arbitrary values in the final equations; also ``mismatching'' between the two strands in a double helix is allowed for.

Anderson's general theory of collision line broadening has been applied to H2O–N2 encounters. The only attractive force was assumed to be that between the H2O dipole, μ=1.87×10—18 esu, and the N2 quadrupole, qN2, an adjustable parameter. A second adjustable parameter, bm, the distance of closest approach, includes the effects of all other forces. The IBM 704 was used in the calculation. Effects of varying the parameters were noted for a number of lines, and in the final calculation, which yielded the widths of all significant type B transitions up to J″=13, parameters qN2=2.62×10—26 esu and bm=3.2 A which give an exact fit of the observed width of the microwave line 6—5—5—1, were adopted. The temperature dependence of the line width over the range 220–2400°K, and the effects of vibration-rotation interactions were also calculated. At 300°K widths vary from 0.11115 cm—1 atmos for 11—1—1 to 0.03200 cm—1 atoms—1 for 14—13—13—13, there being a general decrease in width with increasing J, and at a given J, decreasing width with increasing τ.
Adsorption of Oxygen on Silicon
Authors: Eisinger J. , Law J. T.
Published: January 2005

The sticking probability of oxygen on silicon has been measured as a function of coverage. At room temperature it has a maximum value between 0.01 and 0.02 for low coverage and decreases approximately exponentially as the coverage increases.
Proton Resonance Shifts for the Systems HNO3–H2O and HNO3–KNO3
Authors: Happe James A. , Whittaker A. Greenville
Published: January 2005

Proton resonance shifts have been measured for the concentrated region of the nitric acid-water system and also for the system nitric acid-KNO3. The nitrate ion is very effective in unshielding the protons of nitric acid and further information is presented on the solvation of this ion in the anhydrous acid. Chemical shifts in nitric acid-water solutions are interpreted in terms of the associated nature of nitric acid. The effect of the self-ionization of anhydrous nitric acid on the chemical shift for this liquid is evaluated. Also, it was found that the chemical shift could be used for very accurate analysis of nitric acid-water mixtures in the concentrated acid region.
Theoretical Pre-Exponential Rate Factors for Abstraction Reactions
Authors: Sinanoglu Oktay , Pitzer Kenneth S.
Published: January 2005

Equations have been derived for the pre-exponential rate factors of abstraction reactions. The activated complex is considered as made up of three rigid groups. Classical partition functions are used and it is shown that the use of classical methods gives a simple expression which requires only a knowledge of several force-constants and bond lengths; thus the need for detailed structural information on reactants and complex and for calculations of moments of inertia and vibrational frequencies is eliminated. It is shown that quantum corrections need not be considered in many cases, although if desired, they may be estimated from a graph provided.

The method is applied to four hydrogen abstraction reactions and to the reaction, CCl3Br+Br=CCl3+Br2. Satisfactory agreement is obtained.
Theoretical Investigations on the Light Scattering of Colloidal Spheres. V. Forward Scattering
Authors: Heller Wilfried , Nakagaki Masayuki , Wallach Morton L.
Published: January 2005

The scattering of light, by nonabsorbing colloidal spheres, in the direction of the primary beam (forward direction), is calculated by means of the Mie theory as a function of α and m. The parameters considered are: α=1(1)15 for m=1.05(0.05)1.30 and, in addition, α=0.2(0.2)15.2 for m=1.20. In addition to the i values, the experimentally important quantity, I180/I0c, obtainable by Zimm plots, is evaluated. Its variation with particle size is compared to that of the total turbidity. The performance of the hitherto almost exclusively used Rayleigh-Gans-Debye equation is tested quantitatively against the exact Mie data. The advantages of the ``forward scattering method'' for determining particle sizes are enumerated and a series of desirable definitions and clarifications of angular light scattering quantities are included.
Vibrational Spectra and Structure of Oxamide and Dithiooxamide
Authors: Scott T. A. , Wagner E. L.
Published: January 2005

The infrared spectra of sublimed films of oxamide, dithiooxamide, and their deuterium analogs were obtained at —190° and 25°C in the region from 4000 to 400 cm—1. These spectra are consistent with the x-ray data and satisfactory vibrational assignments were made on the basis of molecules with planar trans heavy-atom structures with over-all site symmetries Ci but close to C2h. An increase in frequency of v(CN) on deuteration accompanied by too large a decrease in δ(ND2) results from a strong mixing of these stretching and bending modes and from Fermi type resonances. Only ordinary hydrogen bonds were found so that the unusually high melting points of these compounds are due to a fortuitous combination of several factors related to their layer structures rather than to very strong hydrogen bonding alone.
Interaction of Rare Gases with Metal Surfaces. I. A, Kr, and Xe on Tungsten
Authors: Ehrlich Gert , Hudda F. G.
Published: January 2005

The interactions of argon, krypton, and xenon with a tungsten surface have been examined in the field emission microscope. Bombardment by rare gas ions results in a penetration of the lattice and an apparent diminution of the work function; bombardment damage is partly annealed between 79° and 300°K. Adsorption lowers the work function by 1.38 ev for Xe, on saturation at 79°K, 1.18 ev for Kr at 20°K, and 0.87 ev for A at the same temperature. The work function diminishes monotonically with Xe coverage even after more than a single layer is formed.

Binding to the surface is structure sensitive—it is strongest around the 100 pole, in the vicinity of the 116 and 130 planes, and weakest at the 111. This sequence of binding energies corresponds to that calculated for different lattice sites on the assumption of dispersion forces. The lowering of the work function caused by adsorption is interpreted as a polarization of the gas atoms by the dipole layer of the metal surface; formally, the interactions at a metal resemble those of the rare gases adsorbed on ionic crystals. Interaction of polarized adatoms and the anti-parallel field applied for electron emission increases the free energy of the adlayer, bringing about rearrangements particularly important for adsorbed argon.

Observations of changes in emission with temperature yield a heat of desorption of 8 kcal/mole for Xe, as well as the following values for the activation energy for surface diffusion: Xe over the (310), toward the (100), ED=3.8 kcal/mole, over the (111), 1.5*lt;ED<3.4 kcal/mole; for the diffusion of Kr and A over the (310) toward the (100), ED>1.1 kcal/mole and ED<0.9 kcal/mole, respectively.
Microwave Spectrum, Structure, and Dipole Moment of Cyclopropene
Authors: Kasai Paul H. , Myers Rollie J. , Eggers D. F. , Wiberg Kenneth B.
Published: January 2005

The microwave spectra of four isotopic species of cyclopropene, CH2(CH)2, CH2CDCH, CH2(CD)2, and CDH(CH)2 were assigned and three rotational constants for each isotopic species were determined. From these data the following structural parameters were evaluated: C–C 1.515 A, C=C 1.300 A, C–H (methylene) 1.087±0.004 A, C–H (vinyl) 1.070 A, H–C–H angle 114°42′±10′ and C=C–H angle 149°55′. The uncertainties in the methylene values are the magnitude of a rotation-vibration interaction correction. The dipole moment of cyclopropene was found to be 0.455±0.01 debye unit.
Variation of Valence State of Eu in SrS Phosphors
Authors: Keller Seymour P.
Published: January 2005

Phosphors containing SrS as the base material and 0.04% Eu as the activator were prepared in various reducing or oxidizing atmospheres. Firings in reducing atmospheres produced divalent Eu and firings in oxidizing atmospheres produced decreasing amounts of divalent Eu and increasing amounts of trivalent Eu depending on the degree of oxidizing character of the atmosphere. The relative amounts of the two valence states were determined by observing the fluorescent emission and by measuring the paramagnetic resonance absorption of the samples.
Empirical Expression for Ionic Character and the Determination of s Hybridization from Nuclear Quadrupole Coupling Constants
Authors: Wilmshurst J. K.
Published: January 2005

An empirical expression between the amount of ionic character in a bond and the electronegativities of the atoms has been suggested. By using the ionic characters determined from this expression, the halogen nuclear quadrupole coupling constants have been interpreted to determine the percentage s hybridization of the halogen bonding orbital. The results indicate that the amount of s hybridization increases with the s hybridization of the bonding atom and with the increasing electronegativity difference of the two atoms in the bond. A qualitative explanation of these results is discussed.
Kinetics of the Thermal Decomposition of Dimethylmercury. I. Cyclopentane Inhibition
Authors: Russell Morley E. , Bernstein Richard B.
Published: January 2005

The kinetics of the pyrolysis of gaseous dimethylmercury have been studied in the presence and absence of cyclopentane inhibitor from 290–375°C for the inhibited and 265–350°C for the uninhibited reactions. The decomposition in excess cyclopentane is first order, with methane the major product (accounting for >95% of the carbon). Rate constants are dependent upon the ratio of dimethylmercury (DMM) to cyclopentane and upon total pressure. The constant for DMM loss is: kD=1.1×1015 exp(—55 900/RT) sec—1. The rate constant (from combined data on DMM loss and CH4 formation) extrapolated to the fully inhibited, high-pressure limit is: k1=5.0×1015 exp(—57 900/RT) sec—1.

The data for the uninhibited decomposition agree with the literature; a partial mechanism is suggested which predicts the transition from chain to nonchain behavior with increasing temperature.

For the inhibited reaction the following mechanism is proposed: (1) Hg(CH3)2→HgCH3+CH3, (2) HgCH3→Hg+CH3, (3) CH3+Hg(CH3)2→CH4+CH3HgCH2, (4) CH3+C5H10→CH4+C5H9, (5) CH3+Hg(CH3)2→C2H6+HgCH3, (6) 2 CH3→C2H6, (7) CH3HgCH2→HgCH3+CH2.

Using the present value of E1=57.9±1.4 kcal/mole in conjunction with known thermochemical data, E2=0±3 kcal/mole. From the inhibition data, k3/k4=0.7±0.2 at 300°C, with a very small temperature coefficient. The inert gas pressure effect is evidence for the unimolecular nature of step (1).
Superposition of Configurations and Natural Spin Orbitals. Applications to the He Problem
Authors: Shull Harrison , Löwdin Per-Olov
Published: January 2005

The method of superposition of configurations is examined in its application to the helium atom in two cases: a 21×21 matrix including all configurations up to 〈6s〉2, and a 20×20 matrix with all configurations up to the 4-quantum level, including angular terms. A new radial limit is established at −2.87900±0.00003, and this is used to discuss the convergence of such expansions in Legendie functions. The variation with scale factor is discussed in detail. The wave functions are analyzed in terms of natural spin orbitals (NSO's), which seem to have many advantages. The first NSO bears a striking resemblance to the Hartree-Fock function, and the first two together provide a close approximation to the solution of the extended Hartree-Fock equations with different orbitals for different electrons. An energy of −2.877924 is obtained for the best (u, v) function found. An analysis of the results suggests that inner orbitals may be better represented by pure exponentials than by Hartree-Fock orbitals whenever additional correlational degrees of freedom are permitted. Expressed in approximate NSO form, the wave function is almost invariant to choice of basis set, provided that the latter is reasonably chosen. In particular, the necessity of including continuum terms along with the discrete hydrogen-like set is demonstrated.
Single-Center Expansions for One-Electron Systems. H2+
Authors: Howell Keith M. , Shull Harrison
Published: January 2005

The expansion of the H2+ wave function in terms of the set of associated Laguerre functions of order (2l+2) based on a single point in space, the molecular midpoint, is studied by the usual variational approach. In particular, the convergence of the expansion is studied as a function of the number and type of basis functions used, the respective scaling parameters, and the internuclear distance. A peculiar behavior with respect to the scaling parameter, in which, for example, for certain optimum choices of the scale parameter for one group of basis functions no improvement is observed upon the addition of one more such function, is proved to occur generally for these functions with one-electron Hamiltonians. This behavior emphasizes the necessity for treating such scale factors as mathematical parameters rather than as constants to be chosen by physical intuition. This single-center expansion is concluded to be only slowly convergent and therefore, the authors feel, likely to have relatively limited use for quantitatively accurate calculations on more complex problems. Such expansions may, however, be useful for certain classes of excited states.
Molecular Configurations of Vinyl Polymers with Strictly Regular Structures and Their Mean Dimensions and Electric Moments in Dilute Solutions
Authors: Nagai Kazuo
Published: January 2005

Neglecting the long-range interaction between segments, general expressions for the mean dimensions and the electric moments of isotactic and syndyotactic vinyl polymers in dilute solutions are derived. For the comparison with experimental results, the following expression is employed for the potential energy of the hindered rotation around C–C links of a skeletal chain: E=(E0/2)[1−cos(θ−θ0)],where θ is a twisted angle from the trans position with θ0 as the most probable one, and E0 is the maximum height of the potential energy. For simplicity numerical calculations of the electric moments are restricted to vinyl polymers in which the direction of the electric moment vector of each substituted group coincides with one of four symmetry axes of tetrahedral model of carbon atom.

For isotactic polymers three cases are examined. The first: all C–C links are twisted in the same manner. The second: consecutive two C–C links are twisted to inverse directions to each other. The third: potential energies of the hindered rotation around C–C links have their minima at the same angles as in crystalline state. From consideration of the minimum distance between two adjacent substituted groups, it is concluded that, if the molecular dimension of isotactic polystyrene is not far apart from that of atactic polystyrene, the deformation of the second type would be less probable. When taken into account the collisions between different parts of the polymer molecule, the deformation of the third type or the other similar to it may be most probable. In this case when 〈R2〉/nb2 is taken to be 12∼13, then 〈u2〉/Nu02 should become 1.5∼1.7, N=n/2 being degree of polymerization. For syndyotactic polymers, two unknown parameters involved in the theory may be uniquely determined by measuring 〈R2〉/nb2 and 〈u2〉/Nu02.
Molecule Formation in the Inert Gases
Authors: Bernardes N. , Primakoff H.
Published: January 2005

The Schrödinger energy eigenvalue equation for the relative motion of two inert gas atoms is solved approximately by fitting a Morse interatomic potential to the generally accepted Lennard-Jones 12–6 interatomic potential. A condition for binding is derived involving the phenomenological parameters present in the 12–6 potential; from the empirical values of these parameters one can then conclude that all the inert gases, except helium, do form stable diatomic molecules. A qualitative argument is presented showing that an hexatomic helium molecule may be stable. The vibration-rotation energy spectrum of the stable inert gas diatomic molecule is discussed. Finally, the partition function for the diatomic molecule is evaluated in an approximate way, whence, using the standard form for the equilibrium constant in terms of partition functions, it follows that at reasonable values of temperature and pressure several percent of the atoms are associated in the form of diatomic molecules.
Irradiation Effects in Simple Organic Solids
Authors: Alger R. S. , Anderson T. H. , Webb L. A.
Published: January 2005

The color centers and free radicals produced in irradiated solid alcohols, ketones, ethers, and other compounds have been examined experimentally by means of optical absorption and EPR spectroscopy to obtain information regarding the products of ionization and the associated electronic processes. At liquid nitrogen temperature these products of electron or x-ray bombardment are stable; however, the color centers are photosensitive and can be bleached both optically and thermally. The alcohols also show an increase in absorption near the characteristic uv bands. Removing the visible color centers increases the EPR hfs, but bleaching in the uv band markedly reduces or changes the hfs. In methanol and ethanol, free radicals are formed with good efficiency requiring about 18 and 12 ev per radical, respectively. Saturation concentrations of 2×1019 and 9×1019 spins per cc were produced in acetone and methanol, respectively. The hfs of ethanol and methanol indicate an alkyl hydrogen is missing from the radicals produced by irradiating these materials. No sign of the atomic hydrogen doublet was observed at liquid nitrogen temperature. Support for the α—β hypothesis was found in the hfs displayed by the irradiated alcohols, paraffins, ketones, and ethers.
Diffusion and Viscosity in a Spherical Cavity
Authors: Broersma S.
Published: January 2005

A system consisting of two, in principle concentric, spherical surfaces separated by a fluid, is considered. The torque and force required to rotate and translate the inner sphere is calculated, as well as the work necessary to maintain fluid flow around it, the flow pattern at the outer sphere being specified. Using this, general expressions for the diffusion constants for rotation and translation for the inner sphere and for the effective viscosity of the bulk liquid are obtained. The inner sphere (a) can be viscous, its surface may slip or adsorb fluid. The effect of a perturbation in the flow pattern at the outer surface (R) is examined. For a small value of a/R, the expressions become those given by Stokes and Einstein for dilute solutions.

For the ratio a/R≈1, the expressions apply to liquids flowing through membranes or porous media. Rotational diffusion of paramagnetic hydrates in diamagnetic environment, translational diffusion of ions through membranes, the viscosity of concentrated suspensions and fluid flow through porous media are discussed.
Destruction of Metastable Helium Atoms in Binary Collisions
Authors: von Roos Oldwig
Published: January 2005

A calculation of the cross section for the reaction He′+He′=He+He++e (destruction of the metastable 23S state by ionization) has been performed by means of the perturbed stationary state method. The cross section obtained is of the order of magnitude 10—18 cm2 at room temperature and increases slowly with decreasing kinetic energy of the colliding particles. The magnitude of the cross section fits well with a tentative scheme which considers processes of the type A′+B=A+B++e as being intermediate between true resonance collisions and nonresonance collisions. It disagrees by 4 orders of magnitude with experimental findings [A. V. Phelps and J. P. Molnar, Phys. Rev. 89, 1202 (1953)]. The reason for this discrepancy is not known.
Biradical Molecular Compounds: A Study by Electron Spin Resonance
Authors: Bijl D. , Kainer H. , Rose-Innes A. C.
Published: January 2005

A number of solid paramagnetic molecular compounds (biradical molecular compounds) with different donor-acceptor tendencies was investigated by electron spin resonance. It was found that (i) the concentration of the paramagnetic compound molecules generally increases with the strength of the donor-acceptor tendency; (ii) this concentration is independent of temperature. The explanation of this situation is a major problem in this field.
Theoretical Investigations on the Light Scattering of Colloidal Spheres. VI. Backward Scattering
Authors: Nakagaki Masayuki , Heller Wilfried
Published: January 2005

Light scattering of nonabsorbing colloidal spheres in the direction towards the incident primary beam (backward direction) is investigated on the basis of the Mie theory. The parameters considered are α = 0.2(0.2)15.2 and m = 1.20. The data obtained are compared with those derived from the Rayleigh-Gans-Debye equation. A simple equation is derived by means of which the α values at maximal and minimal scattering can be calculated in satisfactory approximation. Data of the ``extreme dissymmetry''—i0/i180— are given.
Simple Equation for Estimating the Dipole Moment of a Molecule from Solution Data
Authors: Srivastava Satish Chandra , Charandas P.
Published: January 2005

A simple empirical equation for estimating the dipole moment of a molecule from dielectric constant measurement in solutions without any density and refraction data is suggested. The equation has been shown to be derived from an approximation of the Guggenheim-Smith equation for orientational polarization, as modified by Palit.
Vaporization of Beryllium Oxide and Its Reaction with Tungsten
Authors: Chupka William A. , Berkowitz Joseph , Giese Clayton F.
Published: January 2005

The composition of the vapor above beryllium oxide held in a tungsten Knudsen cell in the range 1900°-2400°K has been determined mass spectrometrically. The vapor consists predominantly of Be and O atoms and (BeO)3 and (BeO)4 molecules. Smaller amounts of the following molecules were detected: O2, BeO, (BeO)2, (BeO)5, (BeO)6, WO2, WO3, and WOx·(BeO)y where x=1, 2 and y=1, 2, 3. A thermodynamic treatment of the data yielded a value of 4.6±0.1 ev for the dissociation energy of the BeO molecule. Heats of vaporization have been measured for the other (BeO)4 molecules and the data suggest a ring structure for these molecules. The boiling point of BeO has been crudely estimated as 3850±200°C at which temperature the vapor consists mostly of (BeO)4 and somewhat smaller amounts of (BeO)3 and (BeO)5. The atomization energies of the WO2 and WO3 molecules have been measured to be 13.6±0.4 ev and 19.3±0.4 ev, respectively. The dissociation energy of the WO molecule is estimated to be about 7.2 ev.
Magnetic Interaction of H3
Authors: Griffing Virginia , Jackson Julius L. , Ransil Bernard J.
Published: January 2005

The results of an LCAO—MO—SCF—CI calculation of the 2Σu ground state of linear H3 are presented and the wave functions obtained from this calculation are used to calculate the general features of the electron spin resonance spectrum. The calculation is carried through for the Fermi contact interaction, which is the principal interaction between the proton and electron spins. It is found that the off-diagonal elements of the hyperfine interaction matrix may not be neglected in that they split degenerate levels. The predicted spectrum, however, does not agree with the observed electron spin resonance spectrum of discharged hydrogen deposited at liquid helium temperatures. In addition the expected electron spin resonance spectrum of H2+ has been calculated from the exact wave function.
Dipole Moment of Tetraborane
Authors: Weaver J. R. , Heitsch C. W. , Parry R. W.
Published: January 2005

The dipole moment of tetraborane, as measured in benzene solution by a heterodyne beat method, is 0.56±0.1.
Near Ultraviolet Spectrum of Crystalline Durene
Authors: Schnepp Otto , McClure Donald S.
Published: January 2005

The absorption and fluorescence spectra of single oriented crystals of durene (symmetric tetramethyl-benzene) were photographed at 20°K in the 2800 A region. The ab plane of the crystal was investigated and it was found that the absorption intensity in the two polarization components in this plane was very nearly equal. The crystal splitting is less than 3 cm—1. The polarization properties of the absorption require the assignment of B2u for the lowest excited state of the parent molecule, benzene.
Kinetics of Nitrogen Atom Recombination
Authors: Herron John T. , Franklin J. L. , Bradt Paul , Dibeler Vernon H.
Published: January 2005

The rate of recombination of nitrogen atoms in the nitrogen afterglow has been measured in a flow system using NO as a titrant and determining the NO content continuously by mass spectrometer. Above about 3 mm of mercury the reaction is predominantly homogeneous and third order. The rate constant, 5.7×1015 cc2 mole—2 sec—1, is independent of temperature in the interval studied (195–450°K). The rate is reduced by substituting helium or argon for N2 as the third body, the ratios of the third-order rate constants with these third bodies being about the same as those for recombination of iodine and bromine atoms. Below about 3 mm of mercury a pseudo-first-order wall recombination becomes important. The recombination coefficient was found to be 1.6×10—5 on a glass wall that undoubtedly was partly poisoned by water.
Estimation of s-Electron Promotional Energies and the Dependence of Orbital Hybridization on Ionicity
Authors: Wilmshurst J. K.
Published: January 2005

A simple electron pairing picture of the chemical bond is used to relate experimental valence state energies to the ionic character, orbital hybridization, and s-electron promotional energy of an atom. A number of s-electron promotional energies have been estimated and, in every case, they are less than s-electron promotional energies calculated from atomic spectral data. The cause of this discrepancy has been suggested as arising from a shifting of the energy levels of the valence electrons on bonding.
Infrared Spectrum of the Dimethylnitrilium Ion
Authors: Turrell George C. , Gordon John E.
Published: January 2005

The infrared spectrum of the dimethylnitrilium ion is presented and discussed. Thirteen of the fifteen infrared active fundamentals expected for the ion on the basis of a C3v′ structure are assigned, and the frequencies of the two remaining fundamentals are estimated from observed combination bands. A calculation of the skeletal bond stretching and bending force constants is given.
Thermodynamic and Spectroscopic Study of Vinylidene Chloride. II. Vibrational Spectra
Authors: Evans J. C.
Published: January 2005

The Raman spectra of vinylidene chloride liquid excited by the 5461-A line and the 4358-A group of lines of the mercury arc have been recorded photoelectrically and some depolarization measurements have been made. The infrared spectrum of the vapor in the 700–320 cm—1 region has also been recorded. These data have enabled some uncertainties in the published vibrational assignment to be resolved but they do not indicate the need for major changes in this assignment.
Temperature Dependence of Proton Relaxation Times in Aqueous Solutions of Paramagnetic Ions
Authors: Bernheim Robert A. , Brown Thomas H. , Gutowsky H. S. , Woessner D. E.
Published: January 2005

The nuclear magnetic relaxation times of protons in aqueous solutions of paramagnetic ions have been measured as a function of temperature. For Mn++ ions, the proton T1 and T2 were measured at 10, 20, and 28 Mc/sec, and for Co++, Cu++, and Gd+++ ions, 20 Mc/sec. The temperature effects observed can be explained by incorporating the proper temperature dependences of the several correlation times into the general Bloembergen-Solomon relaxation expressions.

In the case of Mn++ solutions, which have a T1/T2 ratio of about 5.5 at room temperature and 20 Mc/sec, chemical as well as electron exchange and dipolar interactions are found to be important. Analysis of the data by means of the equations developed provides information concerning the chemical exchange of solvent protons with those in the hydrated Mn++ ion. An activation energy of 8.4 kcal/mole and other parameters for this process are evaluated.

The temperature dependence of T1 and T2 in the Co++, Cu++, and Gd+++ solutions can be explained by the temperature dependence of the dipolar interaction alone. Varying the anion in Cu++ solutions had little effect on T1 or its temperature dependence; also, T1 for Cu++ solutions was found to vary inversely with concentration over the whole temperature range studied.
Emission Spectrum of TeO
Authors: Purbrick R. L.
Published: January 2005

Emission bands of TeO have been discovered on the long wavelength side of previously reported bands. Wavelengths, intensities, and square arrays of the bands are given.
Force Constants of Metal Hexafluorides
Authors: Claassen Howard H.
Published: January 2005

Equations are given relating fundamental frequencies and force constants for a general quadratic potential function for XY6 molecules of symmetry Oh. Tables of force constants are given for hexafluorides of Mo, W, Re, Os, Ir, Pt, U, Np, and Pu.
Zeeman Effect in the 1- to 3-Millimeter Wave Region: Molecular g Factors of Several Light Molecules
Authors: Burrus C. A.
Published: January 2005

The Zeeman effect has been observed in the microwave rotational spectra of several light molecules, and the high-frequency limit of such measurements has been extended for the first time to 1.1 mm wavelength. The magnitudes of the molecular g factors gJ and, where applicable, the components of the g tensor lying along the principal axes of rotation, have been obtained for DBr, DI, CO, PH3, PD3, SO2, O3, H2S, HDS, and D2S. When combined with information from other sources the data have permitted, in addition, a determination of the sign of gJ for DBr and DI, and of the sign of the electric dipole moment of DI.
Oscillation, Rotation, and Spin Relaxation in NO
Authors: Bauer H.-J. , Kneser H. O. , Sittig E.
Published: January 2005

The sound absorption and velocity of NO gas at 293°K was measured from f/p=5×104 to 107 cps/atmos using an ultrasonic pulse method. A maximum of the absorption at 4×105 cps/atmos is ascribed to the relaxation of the oscillational degree of freedom. (τosc=4×10—7 sec at 1 atmos.) According to the absorption at high f/p values, τspin≈4τrot (=2.5·10—9 sec at 1 atmos) seems probable. The result is compared to the corresponding data of O2 and N2.
Calculation of n→II Transition Energies in N-Heterocyclic Molecules by a One-Electron Approximation
Authors: Goodman Lionel , Harrell Robert W.
Published: January 2005

The one-electron LCAO-MO formalism is applied to n→π* transition energies in N-heterocyclic molecules. |βnπspec| is shown to be ∼1 ev smaller than |1βππspec| for (n, π*) states possessing no nodes through nitrogen atoms. Reasonable values are 1βnπspec≈—2.3 ev, 3βnspec≈—2.0 ev. Calculations of transition energies, both singlet-singlet and singlet-triplet, are made for 16 molecules, yielding semiquantitative agreement with experiment. Prediction of the assignment of the lowest excited singlet and triplet levels is made for a number of cases. The singlet-triplet split in the lowest (n, π*) configuration is predicted to undergo a strong orientation dependence in the 6-membered azines. Substitution effects are considered and orientation effects on the n→π* blue shift upon conjugative substitution are treated. (n, π*) states with nodes through nitrogen atoms are discussed qualitatively.
Study of the Effects of Substitution on the Absorption Spectra of Porphin
Authors: Gouterman Martin
Published: January 2005

A model is presented for the excited states of porphin, which are viewed as arising from two configurations which can be mixed to varying degrees. The effects of substituents are then discussed, first the limitations imposed by symmetry requirements and then the requirements imposed if they act as one electron perturbations. The theory is applied to certain experimental problems. First it is shown how the metal porphins can be viewed as a series showing increasing mixing of the two fundamental configurations. Next the effect of free base formation is explained as a cyclic polyene perturbation. This theory predicts that the lowest porphin transition is polarized parallel to the H–H axis. Formulas are derived for intensity changes caused by various external substituents; their effect on transition energies are also discussed. Finally formulas are developed to account for the effects of aza substitution on the methine bridges.
Transport Processes in Liquid Alloys. I. A Transport Cell for Liquid Alloys
Authors: Mangelsdorf Paul C.
Published: January 2005

An electrolysis cell has been devised, using a thin ribbon-shaped capillary, which permits the measurement in a single experiment of the resistivity, the electrolytic mobility, and the diffusion rate in a single sample of liquid alloy. The apparatus has been used to study cadmium amalgams at 25° and 150°C, and the results are found to agree with existing data for each of the three properties. Results on other systems and an overall interpretation are reserved for a subsequent paper.
Ionization Potential and Absorption Coefficients of Nitrogen Dioxide
Authors: Nakayama Toshio , Kitamura Morris Y. , Watanabe K.
Published: January 2005

Absorption coefficients of NO2 were measured at a number of wavelengths in the spectral region 1080–2700 A with a resolution of 0.2 A by a photoelectric method. Several bands observed in the region 1080–1200 A fitted a Rydberg series, and its convergence limit at 11.62 ev was interpreted as the second ionization potential of NO2. The first ionization potential was found to be 9.78 ev by the photoionization method. The ionization continuum showed a break at 10.83 ev which may be due to a probable dissociative-ionization process. Several other electronic transitions corresponding to discrete and continuous absorption are discussed.