bluuebunny/crossref_metadata_2025_split huggingface dataset:
Absolute Infrared Intensities of the Fundamental Vibrations of NF3
Authors: Schatz Paul N. , Levin Ira W. 
Published: January 2005

The absolute infrared intensities of the fundamental vibrations of NF3 have been measured. The results have been interpreted in terms of the N–F bond moment (μ), its derivative (∂μ/∂r), and the unshared pair moment on the N atom (μu.p.). The bond moment obtained from the A1 bending mode is found to be in the vicinity of 1 D. μu.p. is in the vicinity of either 1.2 D or 1.7 D depending upon the sign assumed for the molecular dipole moment. The bond moment calculated from the E mode is quite sensitive to the potential function. Since this function is not known with high accuracy, one is not able to determine whether the bond moments from the two different symmetry species are in agreement.
There is a striking difference in the values of ∂μ/∂r from the two symmetry species with ∂μ/∂r (A1) in the range of 1.5 to 2 D/A and ∂μ/∂r (E) in the vicinity of 4.5 D/A. A qualitative explanation for this difference is offered.
Recalculation of the Latimer, Pitzer, and Slansky Absolute Electrode Potential— A Discussion of Its Operational Significance
Authors: deBethune Andre J. 
Published: January 2005

The Latimer, Pitzer, and Slansky (LPS) calculation of the absolute electrode potential of the standard calomel electrode (StdCE) involves a sequence of processes in which the metals Hg and Na appear. Let Hg be the ``first'' metal and Na the ``second'' metal. The substitution of 21 other metals M for Na as the second metal leads to an array of remarkably self-consistent values. With 16 uni- and divalent second metals M, the LPS potential of the StdCE falls in the range of +0.523 v to +0.693 v (with the Gibbs-Stockholm sign convention) with a mean of +0.599 v and a standard deviation of 0.043 v. The constancy of these values is shown to be thermodynamically reasonable. The LPS method is then generalized to obtain the absolute electrode potentials of 22 other standard electrodes (SMeE) by substituting 22 other ``first'' metals Me for Hg. The generalized LPS absolute potentials of the 22 SMeE's can be converted to that of the StdCE by (1) a simplest, (2) a more refined calculation procedure. The simplest generalized LPS potential of the StdCE is strongly dependent on the choice of the first metal Me, the more refined potential is independent of this choice and agrees with the values obtained above with Hg as first metal.
A conceptual experiment is set up by which it is shown that the LPS potential or any of the generalized LPS potentials of the StdCE can be interpreted operationally as linear combinations of conceptually observable potentials differences, all potentials being taken in ``pieces of the same kind of metal'' (to use Gibbs' phrase). This experiment suggests that the LPS potential of the StdCE is equivalent to the measurable outer or volta potential difference in a free space gap between mercury and electrolyte, when the two phases are in electrical contact. The discrepancy between the LPS calculated value and Klein and Lange's experimental value for this volta PD is discussed, and an experimental value of —98.3 kcal obtained for the standard free energy of hydration of the sodium ion.
Study of the Compressions of Several High Molecular Weight Hydrocarbons
Authors: Cutler W. G. , McMickle R. H. , Webb W. , Schiessler R. W. 
Published: January 2005

Isothermal compressions were measured for thirteen high-purity liquid hydrocarbons and two binary mixtures of liquid hydrocarbons. These hydrocarbons have a molecular weight range of 170 to 351 and included normal paraffins, cycloparaffins, aromatics, and fused ring compounds. The pressure range for these measurements was from atmospheric to as high as 10 000 bars, being limited to lower values for some compounds to avoid possible solidification of the liquid. The volume changes due to pressure were measured at six temperatures spaced about equally in the range 37.8°C to 135.0°C. The volume changes and pressures were measured by methods similar to those of P. W. Bridgman.
Pressure-volume isotherms can be described adequately by the Tait equation, v0—v=C log(1+P/B), or for pressures above a certain minimum, whose value depends on the compound, by the Hudleston equation log[v2/3P/(v01/3−v1/3)]=A+B(v01/3−v1/3).For the Tait equation the parameter C can be predicted for hydrocarbon liquids from the relation C=0.2058 v0.
Compressibility for a given hydrocarbon decreases with increasing pressure at constant temperature and increases with increasing temperature at constant pressure. The compression, and the compressibility, of liquid hydrocarbons are strongly dependent on molecular structure. Cyclization introduces a rigidity of molecular shape which decreases the compressibility markedly. Furthermore, fused ring cyclization as exemplified by naphthyl and decalyl structures has a considerably greater effect in decreasing compressibility than cyclization to nonfused rings such as cyclopentyl, cyclohexyl, or phenyl, even at equivalent carbon atom in ring percentages.
Isobars and isochores were drawn and studied over the full range of temperature and pressure. The coefficient of thermal expansion, (1/v0) (δv/δT) P, for a given hydrocarbon, decreases with increasing pressure at constant temperature. (δ2v/δT2) P undergoes a sign change at a certain pressure, whose value depends on the compound; (δv/δT) P increases with increasing temperature below this pressure and decreases with increasing temperature above this pressure. The pressure coefficient, (δP/δT) v, is not a function of volume alone but is also dependent on the temperature and pressure. (δE/δv) T and (δE/δP) T go to zero and then reverse sign for compounds that can be studied to sufficiently high pressures.
On the T1/T2 Ratio for Protons in Aqueous Mn++ Solutions
Authors: King James , Davidson Norman 
Published: January 2005

The T1≠T2 anomaly for water protons in solutions containing Mn++ has been investigated. At 40 Mc (proton frequency), T1/T2=9.5(±0.5) for Mn++ solutions. When the Mn++ is complexed by the hexadentate ligand, ethylenediaminetetraacetate (MnY—2), or by the tetradentate ligand, nitrilotriacetate (MnX—1), T1 is increased slightly and T2 is increased markedly, so that T1=T2 and the anomaly disappears. For MnX—1, there are probably still 2 H2O molecules complexed to Mn++. EPR studies show that the paramagnetic relaxation time is reduced by complexing (from 3×10—9 sec for Mn++ to 3×10—10 sec for MnX—1). The results therefore support the suggestion by Bloembergen that the anomalous T2 broadening is caused by an AI·S coupling between the electron spin, S, of Mn++ and the proton spins, I, in the coordination sphere plus a long paramagnetic relaxation time. All features of the variation of T1 and T2 with frequency are explained rather well by consideration of the combined effects of the I·S interaction and the dipole interaction.
The experimental results are   Mn++  MnY−2  MnX−1MnX2−4NT1 M sec1.6×10−43.05×10−42.35×10−4NT2 M sec1.65×10−52.6×10−42.25×10−47.4×10−4T1/T29.5(±0.5)1.15(±0.12)1.05(±0.15)
Statistical Mechanics of Irreversible Processes in Polymer Solutions
Authors: Erpenbeck Jerome J. , Kirkwood John G. 
Published: January 2005

The Kirkwood theory of irreversible processes in polymer solutions has been reformulated so as to include all contributions to the frictional forces exerted on the monomer units. The generalized diffusion equation for the nonequilibrium distribution function derived on this basis contains a new perturbation term, dependent upon the external field of force. The solution of this equation may be expressed by a perturbation expansion analogous to that given previously.
The general theory has been applied to the intrinsic viscosity problem. Although the general theory reverts to the previous one, new techniques have been applied which enable the intrinsic viscosity and rigidity to be expressed in terms of the eigenfunctions and eigenvalues of the Oseen interaction tensor and the generalized diffusion operator. Moreover, a second formulation of the viscosity has been devised in which the result appears in terms of appropriate time correlation functions.
Semiempirical Calculation on the Electronic Structure of the Nitrogen-Containing Heterocyclic Molecules. I. General Theory
Authors: Anno Tosinobu 
Published: January 2005

A semiempirical theory for n — π and π — π spectra of nitrogen heterocycles is proposed. The theory is an extension of the semiempirical molecular-orbital method of Pariser and Parr, and the nonbonding electrons localized at the nitrogen atoms as well as π electrons are considered explicitly into the interaction term in the Hamiltonian. The orbitals in which nonbonding electrons are contained may be any 2s—2p hybrids. The differential overlap between atomic orbitals are formally neglected. One-center electronic-interaction integrals are obtained from atomic spectral data and two-center integrals at moderate internuclear distances are extrapolated, using corresponding one-center integrals obtained from atomic spectral data together with the theoretical value of the two-center integrals at larger internuclear distances. On account of the hybrid nature of the nonbonding AO's (AO's from which nonbonding MO's are constructed), various kinds of two-center integrals as well as one-center ones appear. The method of obtaining these integrals is described systematically. The method of obtaining the valence-state ionization potential for nonbonding electrons in hybrid orbitals is also described.
Finally, as an example of the application of the present scheme, the energy levels of the pyrazine molecule are calculated, assuming that the s character of the nonbonding AO at the nitrogen atom is one third and taking account only of interactions among the ground and the singly-excited configurations. Only the singlet levels are considered in this paper. Although the calculated Ag1→B3u1(π−π) transition energy agrees fairly well with experiment, it is found for Ag1→B1u1,B3g1(n−π) transitions that the calculated values are considerably higher than the observed values. This is probably due either to the neglect of the doubly excited configurations or to the invalid assumption concerning the hybridization parameter of the nitrogen nonbonding AO. This point will be discussed in Part II of this series.
Dielectric Properties of Aqueous Ionic Solutions. Parts I and II
Authors: Hasted J. B. , Ritson D. M. , Collie C. H. 
Published: January 2005

The dielectric constants and loss angles of a series of concentrated aqueous ionic solutions have been measured at wave-lengths of 10 cm, 3 cm, and 1.25 cm. From these results the values of the static dielectric constant and relaxation time for these solutions have been calculated on the basis of the Debye formula, which appears to hold accurately. All salts show a lowering of the dielectric constant and a shift in the relaxation time of water. It is found that the dielectric constant ε can be represented by a formula ε=εω+2δ̄c, where εω is the dielectric constant of water, c is the concentration in moles per liter, and δ has values between −7 and −15 for various salts in concentrations of up to 2 M.
In Part I the measurements are described and the results discussed in relation to the structure of ionic solutions. In Part II the validity of the Debye-Sack saturation theory of the dielectric constant and the effects of the fall of dielectric constant on the electrolytic properties of concentrated solutions are discussed.
An Asymptotic Expression for the Energy Levels of the Rigid Asymmetric Rotor
Authors: Golden S. 
Published: January 2005

The energy matrix of the rigid asymmetric rotor, evaluated in terms of symmetric rotor wave functions, has been examined under conditions where J is increased indefinitely. Asymptotically, the energy matrix assumes a form that is very much like the matrix that may be obtained from the characteristic value problem of Mathieu's differential equation. The characteristic values of Mathieu's equation serve as the basis for a good approximation to the energy values of those asymmetric rotor levels which, for a given, large value of J, correspond to a small value of K in the limiting symmetric cases. The differences which exist between the two matrices are accounted for by a perturbation technique which permits an accurate determination of the energy values.
When the characteristic values of Mathieu's equation lead to a successful approximation to the energy values of the asymmetric rotor, an estimate may be made of the asymmetric rotor wave functions.
Internal Molecular Motions of Large Amplitude Illustrated by the Symmetrical Vibration of Ammonia
Authors: Newton R. R. , Thomas L. H. 
Published: January 2005

A general method is developed for separating slow internal motions of molecules from their rapid vibrations, with the rotational motion. The zero approximation for the slow motion can be obtained by Schrödinger's rule from the classical motion in which the rapid vibrations are replaced by constraints.
The theory is applied to the symmetrical double-minimum vibration of ammonia, the combined vibration-rotation energy levels being evaluated as characteristic numbers of a Sturm-Liouville equation in one variable. The microwave absorption frequencies of N14H3 and N15H3 are computed, also the pure rotation frequencies in the far infra-red.
The Reaction of Hydrogen Atoms with Some Oxygen-Containing Organic Compounds
Authors: Trost W. R. , Darwent B. deB. , Steacie E. W. R. 
Published: January 2005

The reactions of atomic hydrogen, produced by a discharge, with methyl ether, acetaldehyde, and ethylene oxide have been investigated.
The main products of the reactions are: from methyl ether—CH4,CO,H2O,C2H6, and HCHO;from acetaldehyde—CH4,CO, and C2H6;from ethylene oxide—CH4,CO, and CH3CHO.
The mechanisms of the reactions are discussed in detail and it is concluded that the primary reactions are: H+CH3OCH3→H2+CH3OCH2E=7.0 kcal.H+CH3CHO →H2+CH3COE≤6.0 kcal.H+(CH2)2O  →H2+C2H3OE=8.5 kcal.,and that the main secondary reactions in all cases are of the atomic cracking type: H+CH3OCH2→CH3+CH3O,H+CH3CO   →CH3+CHOor    →CH4+CO,H+C2H3O   →CH3CHOor    →CH4+CO.
The Temperature Coefficient of the Surface Tension of Liquid Metals
Authors: Skapski Adam S. 
Published: January 2005

The author's approach is based on the conception of ``structure'' of liquids. From rather simple assumptions about the symmetry of configuration of the nearest neighbors the entropy change connected with bringing up N-Avogadro's atoms from the bulk of the liquid into its free surface is estimated and the temperature coefficient of the surface tension is calculated therefrom.
Two entropy terms are taken into consideration. The first term ΔSosc is due to the difference in the frequency of oscillation of the atom inside and on the surface, and is calculated from the respective number of neighbors. This term allows the calculation of the lower limit of the temperature coefficient of the surface tension (because the ``unsharpness'' of the free surface is not accounted for). The second term allows us to estimate—again from the number of the nearest neighbors in the bulk and on the surface—the maximal value ΔSconf, to account for the ``unsharpness'' of the surface.
The experimental data lie well within the calculated limits and almost coincide with the values calculated from (ΔSosc+½ΔSconf)/A where A is the surface occupied by N-Avogadro's atoms. The influence of the thermal expansion is expressed by the change of A with temperature.
Some Characteristic Frequencies in the Raman Spectra of Saturated Aliphatic Hydrocarbons
Authors: Sheppard N. 
Published: January 2005

An analysis of the data presented in a recent compilation of Raman spectra of saturated hydrocarbons has been carried through with a view to the determination and assignment of vibration frequencies that are characteristic of particular molecular groups.
Suggested approximate assignments have been made for the rocking and wagging modes of CH2 groups (720–760 cm−1 and 1300–1340 cm−1, respectively) and for the deformation modes of CH groups (1330–1360 cm−1) in such hydrocarbon molecules.
Assignments previously made for the analysis of the Raman spectra of isobutane (trimethyl methane) and neopentane (tetramethyl methane) have been reviewed, and the results applied to the interpretation of observed characteristic frequencies of singly and double branched paraffins. Single branching of the hydrocarbons gives rise to characteristic frequencies in the regions 1180–1140 cm−1 and 830–790 cm−1, whereas double branching gives similar frequencies in the regions 1260–1190 cm−1 and 760–710 cm−1. These can probably be assigned to C–C stretching modes of vibration of the molecules. Other characteristic frequencies in the regions 970–950 cm−1 and 930–910 cm−1 occur in the spectra of single and doubly branched hydrocarbons, respectively, when these have at least two methyl groups attached to the branching carbon atom. They are probably caused by methyl wagging modes of these groups.
Dielectric Behavior of Solutions of Electrolytes in Solvents of Low Dielectric Constant. IV.A. Dielectric Absorption of Butyl Alcohol, B. The Second Wien Effect1
Authors: Strobel H. A. , Eckstrom H. C. 
Published: January 2005

A. The absorption conductivity of n-butyl alcohol has been carefully determined by a calorimetric method, using two independent, specially purified samples. Its dielectric behavior proved in good agreement with Debye theory. The probable source of the error in earlier butyl alcohol measurements determined with the same apparatus was ascertained. A critical frequency of 305 Mc was calculated, which is about the average of most good literature values.
B. Several benzene solutions between 0.001–0.008 molar have shown increases in conductance with field strength at 60 cycles per second in accord with Onsager's theoretical treatment of the second Wien effect.
Nonreactive Molecular Encounters
Authors: Levine R. D. 
Published: January 2005

Low-energy molecular collisions are discussed from a point of view that emphasizes the role of the internal degrees of freedom of the colliding molecules. The theory centers attention on the mechanism of energy transfer from kinetic energy of relative motion into internal energy and vice versa. It is shown that irrespective of the over-all energy transfer (which may be zero), the collision event proceeds via steps of energy migration between internal and relative degrees of freedom. This feature is absent in the available first-order theories. An approximation scheme which includes this feature even in first order is suggested, and a self-consistent-field scheme where each collision partner moves in the average field of the other partner is discussed.
The migration of kinetic energy into internal degrees of freedom results in the temporary formation of bound states. Such intermediates are of importance in the study of intermolecular forces, vibrational excitations, contact charge-transfer complexes, and three-body recombinations. The collision of two hydrogen atoms is discussed in the adiabatic approximation, where the temporary bound state is due to charge redistribution. The mechanism of three-body recombination is discussed and a recombination rate constant is calculated.
Application of Low-Field NMR to the Unambiguous Assignment of Spin-Coupling Parameters. I. Pentafluoro-Iodobenzene
Authors: Moniz William B. , Lustig Ernest 
Published: January 2005

A low-frequency internal-lock spectrometer system, obtained by substitution of a 6.14-MHz rf unit and probe in a Varian HA−100 spectrometer, makes it possible to record high-quality precalibrated 1H and 19F spectra at about 1.5 kG. Since at such field strengths, chemical shifts are reduced by about one order of magnitude compared to usual conditions, determinations of relative signs of coupling constants (J's) and assignment of J's to particular pairs of nuclei can be made in many cases in which this is not possible at 14 or 23 kG due to ``first-order'' characteristics of spectra.
In this way, the relative signs of the three meta JFF's in C6F5I were determined, and the values of −4.95 and −1.22 Hz were unambiguously assigned to J26 and J35, respectively. (These signs are based on ortho JFF&lt;0, as found in a preliminary analysis of the 6.14-MHz spectrum of C6HF5.) In general, low-frequency (∼6 MHz) field-lock NMR spectroscopy yields detailed information on spin coupling constants, when ``non-first-order'' conditions can thus be created.
Chemiluminescence of CH in the O +C2H2 Reaction : Rotational Relaxation and Quenching
Authors: Brennen W. , Carrington Tucker 
Published: January 2005

Rotational distributions of CH (A 2Δ, v=0) were measured at pressures from 0.1 to 8.5 torr in the O+C2H2 reaction in the presence of large excess of N2, Ar, or He. The reaction N+NO→N2+O was used to produce O without O2. Under all conditions the distributions are found to be a superposition of two Boltzmann distributions, one at 1200°—1400°K characteristic of the process leading to the formation of excited CH (A 2Δ), and one which stays close to the temperature of the reactor. Assuming that the observed behavior of the rotational distributions is caused by collisions of excited CH with heat-bath molecules and interpreting the fraction of molecules in this low-temperature distribution as a measure of the extent of relaxation of the initial rotational distribution of excited CH, average relaxation rate constants are derived. With the collision partners mentioned above, 10 to 30 collisions are required for relaxation. A 14-level phenomenological model including only transitions between neighboring rotational levels (K→K±1) fits the experimental distributions well at all pressures studied if the downward rate constants kK−1,K are approximately proportional to exp(−2BK/kT), where B=14.6 cm−1 is the rotational constant for CH(A 2Δ, v=0) and T=360°K. Other models are discussed. Rotational and vibrational distributions for CD(A 2Δ) are also described. Quenching of the CH(A→X) emission by added oxygen was studied quantitatively and the results are consistent with a mechanism in which not CH(A 2Δ) but a precursor to its formation is removed by O2. In the absence of O2 the lifetime of the precursor is determined primarily by the atomic-oxygen concentration.
When an electrical discharge through O2 is used as the source of oxygen atoms for reaction with acetylene, the rotational distribution of CH(A 2Δ) and its pressure dependence is quite different from that described above. When acetylene reacts with the products of a discharge through CO2 with excess CO2 as heat bath, the rotational distribution of CH(A 2Δ) has a Boltzmann form at all pressures, with only the rotational temperature depending on pressure and approaching the gas kinetic temperature at high pressure.