bluuebunny/crossref_metadata_2025 huggingface dataset:
Vacuum-Ultraviolet Photochemistry. II. Solid- and Gas-Phase Photolysis of Methane—Water Systems
Authors: Stief L. J. , DeCarlo V. J. , Hillman J. J.
Published: January 2005

The photolysis of the methane hydrate (CH4·6H2O) at −195°C at 1470 and 1236 Å has been investigated. Mixtures of methane and water in the gas phase have also been photolyzed at 1470, at 1236 Å, and in the region 1450–1850 Å. In both gas- and solid-phase photolysis, CO and CO2 are formed at 1470 and 1236 Å. CO2 is formed from CO, probably by the reaction OH+CO→CO2+H, which is shown to occur readily in the solid at −196°C.

In the photolysis of CH4·6H2O at −196°C, the hydrogen produced is mainly from the methane. Ethane is formed as well, and the product ratio CO2/C2H6 is a linear function of the ratio of the reactants H2O/CH4. Formation of CO2 and C2H6 by competitive reactions of CH2 with H2O and CH4 is suggested.

Similarity of results at 1236 Å to those at 1470 Å suggests that CH2 is present in both systems. Since photodecomposition of CH4 is negligible at 1470 Å, the production of CH2 at this wavelength is attributed to the occurrence of O+CH4→CH2+H2O with oxygen atoms being formed in photolysis of water.
Normal Frequencies of Skeletal Bending Vibration of Planar Zigzag Chain with Finite Length
Authors: Okada Kenkichi
Published: January 2005

This paper is part of a program for theoretical study of the end effects on the normal vibrations of chain molecules with finite length. Transfer matrix method is applied to calculate normal frequencies of a mode corresponding to ν5 of polymethylene chain of length N=3 through 40. Rigid-bond model is employed with the assumption of valence force field. In the case with an extremal frequency in the dispersion relation of the system, a general relation is found near the extremum: difference between two real phases which correspond to a normal frequency is an integral multiple of π over the effective length N* expressed in terms of true length N and the boundary condition imposed. A method of analysis for this case is presented to determine the dispersion relation from the observed data. The method is tested about its applicability by regarding the calculated frequencies as ``observed.'' The method is applied to the infrared absorption data of n-fatty acids near 500 cm−1 giving the result ν=520–131{2kπ/[N+1.046±1.755 cos(1.117N−0.932)]}2 (cm−1)  (k=1,2,···).
On the Interpretation of Molecular Spectra in Odd-Membered Aromatic Compounds
Authors: Feitelson Jehuda
Published: January 2005

Molecular-state functions, based on the perimeter model, were constructed for odd-membered aromatic molecules. The electronic spectra of the tropylium, benztropylium, and three dibenztropylium positive ions were calculated by first-order configuration interaction (i.e., by interaction between the four states of the first excited configuration) and subsequent perturbation of the ring by cross links. The results are compared with the experimental values and calculation of Heilbronner and Murrell. The heteroaromatic indene compounds indole, indolizine, and methyl pyrindine, as well as their aza-substituted derivatives were similarly investigated. The main features of these spectra are the splitting of the E1u and Enu perimeter degenerate states and the shifts of the state energies by the inductive effect. The latter depends mainly upon the difference in charge densities between ground and excited state at the sites of substitution in the molecule. The agreement with the observed spectra is generally good. However, in carbazole, quantitative agreement is not achieved, though the predicted features of the spectrum are observed.
Crystal Structure of the Transition-Metal Molybdates. I. Paramagnetic Alpha-MnMoO4
Authors: Abrahams S. C. , Reddy J. M.
Published: January 2005

Paramagnetic alpha-MnMoO4, the stable phase at STP, is monoclinic with lattice constants a=10.469±0.005, b=9.516±0.005, c=7.143±0.005 Å, and β=106°17′±6′, and space group C2/m. The crystal structure has been solved and refined by a combination of three-dimensional Patterson and Fourier series and by the method of least squares. 1873 independent integrated intensities were measured by PEXRAD; the final agreement factor between measured and calculated structure factors is 0.0574. Two crystallographically independent Mn atoms are surrounded by highly distorted oxygen octahedra; the Mn–O distance varies between 2.091±0.006 and 2.252±0.003 Å, with average length 2.164 Å. Two crystallographically independent Mo atoms are surrounded by slightly distorted oxygen tetrahedra, with Mo–O distances ranging from 1.724±0.005 to 1.851±0.004 Å, the average being 1.761 Å. The thermal vibrations are significantly anisotropic. An analysis is given of various current methods for estimating the standard deviation in the measured structure factor.
Discreteness-of-Charge Adsorption Micropotentials. II. Single Imaging
Authors: Barlow C. A. , Macdonald J. R.
Published: January 2005

Methods are developed for calculating exact potentials and fields arising from discrete hexagonal arrays of monopoles imaged by a perfect conductor. They allow calculation of the potential and field at any point outside a plane electrode upon which such a hexagonal array of charges (of infinite extent) is adsorbed, and are applied to the problem of determining various electrical properties of such adsorbed arrays. We give particular attention to the micropotential and energy of adsorption for ionic adsorption in both electrolytic and gaseous systems and consider further application of the results to electron emission from metals. Detailed comparison with earlier approximate treatments is made, and when appropriate, errors appearing there are corrected. For example, we find that the rearrangement energy on incremental adsorption of ions does not vanish, as previously suggested, except for a nonphysical limit. Exact results are obtained for the rearrangement energy, and it is usually found to be a significant contribution to the total adsorption energy. Sufficient graphical and numerical results are given for all computed quantities so as to be of direct use to the worker in this general area.
Angular Correlation Functions: Application to Dielectric Absorption in Polar Fluids
Authors: Steele William A.
Published: January 2005

In recent work on the theory of dielectric absorption, the complex dielectric constant has been expressed as a function of the correlation function of the electric moments of the system. Here, the equations are written down which relate this correlation function to the time-dependent distribution functions for molecular orientation. Two model calculations of the singlet angular distribution function are discussed; and the pair-wise distribution function is related to the singlet motion by an extension of the convolution approximation to rotational motion. The correlation function of the permanent dipole moments is obtained from these distribution functions, and the contribution of induced dipoles to the correlation function of the moments is briefly discussed. Finally, the theoretical expressions developed here are applied in a partial analysis of the dielectric absorption properties of liquid water.
Improved Free-Volume Theory of Liquids. VI. Further Tests of the Worm Model for the 12–6 Potential
Authors: Chung Harold S. , Dahler John S.
Published: January 2005

The worm theory of liquids has been tested over a rather broad range of physical conditions. Although the theory does represent a considerable improvement over the earlier cell theories, it generates accurate estimates of the thermodynamical functions and of the equation of state only for restricted ranges of temperature and pressure. The basis for this conclusion is provided by the comparisons of theory and experiment given in this and in a previous paper.
On the Quantum-Mechanical Fokker—Planck Equation
Authors: Davis H. Ted , Hiroike Kazuo , Rice Stuart A.
Published: January 2005

Taking the Wigner function as the basic N-body distribution function, quantum-mechanical modifications to the Fokker—Planck equation are studied using the two different approaches introduced, respectively, by Kirkwood and Prigogine. In Sec. II the weak coupling limit is studied using the time-smoothing technique first introduced by Kirkwood; the results of this section can perhaps form the basis of an approximate treatment of the transport phenomena of pure liquids. In Sec. III we treat the problem of the Brownian motion of a heavy particle employing the perturbation techniques developed by Prigogine and co-workers; in this section it is found that the form of the quantum-mechanical Fokker—Planck equation is identical to the classical equation, but that the friction coefficient contains quantum-mechanical corrections. Finally, it is noted that the weak coupling result obtained by the time-smoothing technique is identical to the approximation of small momentum transfer (Sec. III), if in the latter case the scattering cross section is represented in the Born approximation.
On the Theory of Chemiluminescent Electron-Transfer Reactions
Authors: Marcus R. A.
Published: January 2005

A mechanism is described for chemiluminescent electron-transfer reactions. It is shown that in the case of very exothermic homogeneous electron-transfer reactions, the intersection of the potential-energy surface of the reactants with that of electronically unexcited products occurs only at high energies. The rate of formation of unexcited products then becomes slow. A numerical estimate of this slowness is made using known homogeneous rate constants for ordinary electron-exchange reactions. An intersection occurs at lower energies when one of the products of a highly exothermic electron transfer is electronically excited, thereby reducing the exothermicity. The product may emit light or subsequently form a state that does.

A rather different situation is shown to occur at electrodes: the system can now reduce the ``exothermicity'' by having the electron transfer into a high unoccupied level of the conduction band or from a low occupied level of the latter. The large width of the conduction band in metals permits much latitude in reducing the exothermicity thereby.

These results are compared with present experimental findings that chemiluminescent electron transfers occur in solution rather than on electrode surfaces.
Hexamethylenetetramine Hexahydrate: A New Type of Clathrate Hydrate
Authors: Mak Thomas C. W.
Published: January 2005

The crystal structure of hexamethylenetetramine hexahydrate, (CH2)6N4·6H2O, has been determined using three-dimensional x-ray data collected at −20°C. The analysis revealed a novel type of clathrate structure characterized by hydrogen-bonding interaction between the host and guest species. The water molecules form a hydrogen-bonded framework consisting of staggered columns of slightly puckered (H2O)6 rings cross linked to one another. Half of the water protons are in ordered arrangement in the crystal and the other half are twofold disordered. Each hexamethylenetetramine molecule is located in a cage within the clathrate framework, and is hydrogen bonded to the water lattice through three of its four nitrogen atoms.
Optical Absorption Spectrum of Mn2+ in Cubic and Tetragonal Ligand Fields
Authors: Goode D. H.
Published: January 2005

The fine-line absorption spectra of the Mn2+ ion in MnCl2·6NH3, MnCl2·2H2O, nNH4Cl·MnCl2·2H2O, and KCl·MnCl2·2H2O have been measured at low temperatures. The ion lies at a site of cubic symmetry in the amine and approximate tetragonal symmetry in the hydrates. A cubic ligand field calculation has been made for the d5 configuration which includes spin—orbit coupling and with it level splittings and doublet intensities are discussed. The calculations were further extended to include a tetragonal distortion and were then able to reproduce reasonably well the fine structure in the 4T2 level of the hydrates observed at 27 000 cm−1.
Magnetic Characteristics of Compounds of Cerium and Praseodymium with Va Elements
Authors: Tsuchida T. , Wallace W. E.
Published: January 2005

The magnetic behavior of CeP, CeAs, CeSb, PrP, PrAs, and PrSb has been investigated over the temperature range extending from 4° to 300°K. Curie—Weiss behavior is observed for all compounds in the upper portion of the temperature range studied with effective moments in fair agreement with those expected for the free tripositive ions. The cerium compounds have Néel points at temperatures ranging from 8° to 25°K. The praseodymium compounds give no evidence of magnetic ordering. At low temperatures they exhibit the Van Vleck temperature-independent paramagnetism. This is attributed to the influence of the crystal field in splitting the ninefold degenerate ground state of the free Pr3+ ion. The susceptibility—temperature behavior of PrSb can be accounted for in terms of a single parameter from which an over-all crystal field splitting of 157 cm−1 is deduced. Similar attempts for PrP and PrAs were unsuccessful, presumably because of the increased importance of nonlinear shielding effects in these materials. The results for CeP and CeAs indicate partial quadrivalency of Ce in these compounds. Results for CeSb are very complex; indications are that this compound orders in several stages.
Diffusion Measurement of Mn+ + in Single-Crystal NaCl Using Electron Spin Resonance Absorption Intensity
Authors: Stewart W. H. , Reed C. A.
Published: January 2005

Electron paramagnetic resonance intensity measurements were used to ascertain the diffusion parameters of Mn+ + in NaCl. It was found that for high concentrations the diffusivity was essentially concentration-independent and could be described by the equation D = D0 exp(—φ/kT) over the entire range of temperatures investigated. The parameters were D0= (3.48±1.32)×10−3 cm2/sec and φ=0.954±0.037 eV. Diffusion was from a large source deposited from solution on the surface of a polished NaCl crystal. After a diffusion anneal in an inert atmosphere the crystals were sectioned with a microtome. The collected sections were placed in special sample tubes and run in an X-band spectrometer. Relative intensity measurements were used to find the appropriate concentration curves.
Phase Diagrams of Sodium Sulfate and Sodium Chromate to 45 kbar
Authors: Pistorius Carl W. F. T.
Published: January 2005

The phase diagrams of Na2SO4 and Na2CrO4 have been determined to 45 kbar. Two new high-pressure phases have been found for Na2SO4. Eight different solid phases, one of which is metastable, are now known for this substance. Three new high-pressure phases have been found for Na2CrO4. The melting curves of Na2SO4 and Na2CrO4 have been determined to 7 and 34 kbar, respectively. The initial slopes of the melting curves are identical within experimental error. The phase diagrams of Na2SO4 and Na2CrO4 are strikingly similar, and there are reasons for believing that every known polymorph of Na2CrO4 has an isostructural counterpart in the phase diagram of Na2SO4.
Solution Dimerization of the Tetracyanoquinodimethane Ion Radical
Authors: Boyd Richard H. , Phillips William D.
Published: January 2005

The reversible dimerization of the anion radical of 7,7,8,8-tetracyanoquinodimethane in aqueous solution has been studied spectroscopically. Analysis of the spectra yields an equilibrium constant for dimerization (2A−⇆A2=) at 25° of 2.5×103 liter/mole and a heat of dimerization of −10.4 kcal/mole dimer.
Medium Effects in Nuclear Magnetic Resonance. IV. A Refined Theory for Nonpolar Gases
Authors: Rummens F. H. A. , Bernstein H. J.
Published: January 2005

Following the general theory for medium NMR shifts in gases as outlined in Part I of this series, two improvements are proposed. For the calculation of the van der Waals interaction a repulsive term has been added to the customary attractive term. Wherever intermolecular distances are required, a properly averaged distance between the site of the measured proton in the solute molecule and the center of the solvent molecule is used rather than the distance between the centers of the molecules. The implications of these corrections for nonpolar molecules are discussed, and new values for the bond parameters B are proposed.
Infrared-Absorption Spectrum and Ferroelectric Behavior of Sodium Trihydroselenite
Authors: Khanna R. K. , Decius J. C. , Lippincott E. R.
Published: January 2005

The infrared-absorption spectra of sodium trihydroselenite have been investigated in both the ferroelectric as well as the nonferroelectric phases. The analysis of the data suggests that in the ferroelectric phase the units HSeO3− and H2SeO3 are distinct with hydrogen bonds connecting their oxygens. The transition to the nonferroelectric phase results in the two units becoming equivalent, each behaving like a pyramidal SeO3= ion. This is explained in terms of the motion of the protons in a potential field which, in the ferroelectric phase, has an asymmetric double minimum. The transition to the nonferroelectric phase is accompanied by an even distribution of proton density along the bond length which, on the basis of our data, seems to be due to the potential field acquiring a single minimum.

Based on these results an attempt has been made to suggest a plausible switching mechanism in the ferroelectric phase and to correlate the spectral changes accompanying transition with the changes in the crystal structure.
Thermodynamics of Parabolic Time Rate Law of Oxidation of Metals
Authors: Yao Y. L.
Published: January 2005

The Wagner equation for the isothermal oxidation of metals is re-established. One of the assumptions used in deriving the equation is removed.
Adsorption and Surface Diffusion of Copper on Tungsten
Authors: Melmed Allan J.
Published: January 2005

The Cu/W adsorption system was studied by field-emission microscopy. Adsorption of one to ten atomic layers of Cu was followed through changes in the field-electron-emission pattern and average work function of the W field emitter. Surface diffusion was investigated for single-, double-, and triple-layer diffusion, and for successive diffusion of one layer of Cu on others up to four layers. The negative electric field used in some of the measurements was found to decrease the apparent activation energy and the pre-exponential factor of the diffusion equation. The activation energy varied over the tungsten surface, increasing with surface roughness; it also varied with coverage, decreasing rapidly at first and then slowly with increasing coverage. It is suggested that the limiting values of Q and D0 approximate the values for surface self-diffusion of Cu.
Electron Spin Resonance Spectrum of the Radical Anion of 1,3,5-Cycloheptatriene and the Spin Polarization Constant QC′CHH
Authors: Levy Donald H. , Myers Rollie J.
Published: January 2005

The radical anion of 1,3,5-cycloheptatriene has been prepared by electrolysis in liquid ammonia. The proton hyperfine structure of its electron spin resonance spectrum was assigned with A(1, 6)=7.64, A(2, 5)=0.59, A(3,4)=4.90, and A(7)=2.16 G. Satisfactory agreement between calculated and observed coupling constants is only obtained if the radical anion is assumed to have a nonplanar boat conformation and if the methylene coupling is assumed to arise primarily from spin polarization by the spin density on adjacent carbon atoms. A value for this spin-polarization constant is obtained and we find that either QC′CHH=4.33 or −3.09 G. The recent data of Morton are in good agreement with the positive value, but the theoretical calculation by Colpa and de Boer indicate that it should be probably negative in sign.
Spin—Orbit Coupling and Electron-Affinity Determinations from Radiative Capture of Electrons by Oxygen Atoms
Authors: Berry R. Stephen , Mackie John C. , Taylor Raymond L. , Lynch Robert
Published: January 2005

The radiative capture continuum for the process O0+e→O−+hν is studied in the region of the threshold, 7800–8800 Å. The spectrum is produced in shock-heated vapors of potassium peroxide and rubidium oxide in neon and argon. Individual thresolds are resolved which correspond to the transitions O(3P2)→O−(2P12),O(3P2)→O−(2P32),O(3P1)→O−(2P32), and possibly O(3P0)→O−(2P12). From these thresholds, the electron affinity of the oxygen atom is determined to be 1.478±0.002 eV and the separation of P212,P212 states of O−, 285±15 cm−1, corresponding to a spin—orbit coupling constant of 190±10 cm−1 for the oxygen negative atomic ion.
Ground-State Energy of an Electron Gas in a Lattice of Positive Ions—Cohesive Energy of Alkali Metals and Alloys
Authors: De Leener M. , Bellemans A.
Published: January 2005

Our previous calculations for the ground-state energy of a high-density electron gas in a lattice of positive point ions are extended to lattices of real ions with a core of bound electrons. The core effect on the electron gas is taken into account by the method of pseudopotentials put forward by Cohen and Heine. Both cases of lattices covered with one species and two species of ions are discussed.

The present model should give a rough picture of metals and alloys and was subsequently applied to alkali metals for which rather simple pseudopotentials have been proposed by Cohen. Numerical results obtained for the cohesion energy of the electron gas and the lattice of ions agree fairly well with the data of pure alkali metals. The heats of mixing of alkali metals have also been calculated with this model: They are very small and agree roughly with the order of magnitude of the experimental data.
Crystal Structure of Porphine
Authors: Webb Lawrence E. , Fleischer Everly B.
Published: January 2005

The crystal structure of porphine, the parent compound in the porphyrin series, was determined by x-ray diffraction analysis. The phases of the normalized structure factors were obtained by the probability methods of Hauptman and Karle. The crystals are monoclinic with four molecules per unit cell, and the C2h5—P21/a space group requires no molecular symmetry. Observed small deviations from planarity are not large enough to be significant. Comparison of the crystal structures of several porphyrins indicates that the porphine skeleton is probably planar or nearly planar in the vapor phase, although marked ruffling occurs in some crystals because of crystal-packing forces. The wide variation in molecular configuration found in different crystals emphasizes the easy deformability of the molecule; this property may be important in biological systems.
High-Resolution Infrared Spectra of Cyanogen and Cyanogen-15N2
Authors: Maki Arthur G.
Published: January 2005

The infrared absorption of 12C214N2 and 12C215N2 has been studied with a resolution of 0.08 to 0.04 cm−1. The vibration—rotation band constants were determined for eight vibrational transitions of 12C214N2 and three vibrational transitions of 12C215N2. Many unresolved hot-band Q branches were also measured. The values for many vibrational and rotational constants are given. The bond distances determined from the rotational analysis, and their three-standard-deviation error limits, are r0 (C–C) = 1.389±0.030 Å and r0 (C≡N) = 1.154±0.017 Å. The N–N distance and corresponding error limits are 3.697±0.010 Å.
Surface Rate Processes and Sensitivity of High Explosives
Authors: Chaiken R. F. , Cheselske F. J.
Published: January 2005

The nature and rate of linear surface regression of TNT, RDX, Tetryl, and PETN have been studied utilizing a hot-plate pyrolysis technique over surface temperatures ranging as high as 500°C. The data, when compared to similar data for benzoic acid, suggest that the primary surface rate process appears to be an endothermic melt flow having an apparent activation energy suggestive of heat transfer and viscous flow as a rate controlling step.

These data, when used as a measure of surface heat dissipation, correlate very well with the measured values of impact sensitivity. Also, they offer an explanation for the fact that attempts to correlate impact and/or friction sensitivity with melting point alone could lead to misleading results when PETN and RDX are considered.
Quantum Chemistry of Electrode Processes. I. General Relations for Electron Exchange between Electrode and Electroactive Species under Equilibrium and Nonequilibrium Conditions
Authors: Schmidt Parbury P. , Mark Harry B.
Published: January 2005

It is assumed in this paper that at the electrode—solution interface there is molecular order of the electroactive species resembling solid-state order. Specifically, it is assumed that next to the electrode is a layer of adsorbed neutral solvent molecules which are also ligands coordinated to the ions found in the interface. The mechanism of electron transfer from the electrode to the ion or the reverse from the ion to the electrode is assumed initially to involve a transition from either the electrode or the ion to the solvent molecule. This is followed by a transition of the electron from the solvent molecule to either the ion or the electrode. The two transitions involved in the net transfer of an electron across the interface are considered analogous to the charge-transfer mechanism of spectroscopy. The wavefunctions representing the system at the interface are then of the same form as the charge-transfer wavefunctions given by Mulliken.

By considering the radiationless transition probabilities for the electron transitions in the interface system at the electrode, it is found that the usual current expressions result. By imposing the condition of zero net current at equilibrium the Nernst equation results. By further considering the polarization of the electrode under nonequilibrium conditions as a perturbation of the energy levels of the system, it is found that with the proper identification of terms the current expression for the polarized electrode results.
Energy Levels and Rate Processes in the Thallium Activated Potassium Chloride Phosphor
Authors: Johnson Peter D. , Williams Ferd E.
Published: January 2005

The dependence of spectral distribution and intensity of emission of KCl: Tl on temperature and excitation wavelength are correlated with absorption data and theoretical calculations to provide a detailed picture of the energy relationships in this phosphor. The two principal excited states are the 1P10 and 3P10 states of Tl+ and are found to be approximately in thermal equilibrium with each other. The equilibrium is disturbed by emission, and the 4750A emission is favored by 1960A excitation and the 3050A emission is favored by 2470A excitation. The former processes are attributed to 1P10↔1S0 transitions; the latter, to 3P10↔1S0 transitions. The rate processes are formulated and the specific rate constants deduced. The presence of Tl+ or Cd++ adjacent to the activator induces additional excitation and emission bands. The activation energy for radiationless de-excitation has been computed theoretically and found to be in accord with experiment.
Electron Deficient Compounds. VI. The Structure of Beryllium Chloride
Authors: Rundle R. E. , Lewis Paul H.
Published: January 2005

The simple compound, beryllium chloride, offers an opportunity to study halogen bridge bonding. Beryllium chloride is isomorphous with dimethylberyllium and silicon disulfide. The orthorhombic unit, a0=9.86, b0=5.36, c0=5.26A contains four beryllium chloride molecules. The structure consists of continuous chains:[Complex chemical formula]with an essentially tetrahedral configuration about beryllium. The Cl–Be–Cl bond angle within the four membered rings is 98.2° which is less than the tetrahedral angle, as is found in SiS2, instead of more, as in dimethylberyllium. The bond angles indicate that all bonds in beryllium chloride contain an electron pair, so that chlorine uses an unshared pair in forming bridge bonds. Hence, chlorides isomorphous with electron deficient metal alkyls are not to be classified as electron deficient compounds.
Statistical Thermodynamics of the Transition Region between Two Phases. II. One Component System with a Plane Interface
Authors: Hill Terrell L.
Published: January 2005

An approximate statistical theory is used to investigate the nature of the density transition curve in passing from a one component liquid phase to the equilibrium vapor phase. This density curve is related thermodynamically to the surface tension, the surface energy, the location of the surface of tension, and to the dependence of surface tension on curvature.
On the Measurement of Vapor Pressures by Effusion
Authors: Whitman Charles I.
Published: January 2005

The effect of apparatus dimensions on the accuracy of vapor pressure measurements by Knudsen's effusion method is discussed for the usual type of experimental arrangement. It is shown that the total surface area of a condensed solid phase is not fundamentally related to the pressure of the effusing vapor. Equations are derived which may be used to check the pressure of the effusing vapor for saturation. Two cases in the literature are discussed.
The Temperature Dependence of the Solubility of Solid Nonelectrolytes
Authors: Hildebrand J. H.
Published: January 2005

The solubilities of nonelectrolytes in solutions from which chemical interactions are absent, when plotted as logarithm of mole fraction vs logarithm of absolute temperature, yield practically straight lines except near the melting point of the solute. This offers a superior method of smoothing out solubility data and of predicting the temperature coefficient of solubility from a single point by comparison with neighboring lines for other solvents.

An explanation is given for this behavior.
The Microwave Spectrum of a Slightly Aspherical Top—The Structure and Dipole Moment of Sulfuryl Fluoride
Authors: Fristrom Robert M.
Published: January 2005

The microwave spectrum of the slightly aspherical rotor, sulfuryl fluoride, has been investigated. Seven lines were found in the twenty to thirty thousand megacycle region. Six of these lines were assigned to J=1→2 and 2→3 rotational transitions of the molecule S32O2F2 and the other to the 111→212 transition of S34O2F2. These lines can be fitted to within the limits of experimental error (0.002 percent) with the following reciprocal moments of inertia: a32=5139.77 mc              a34=5139.77 mcb32=5077.81 mc              b34=5073.00 mcc32=5057.22 mc              c34=5052.51 mc

Structural parameters were determined from these moments and the assumption of C2v symmetry. The latter was confirmed by intensity measurements. S–O 1.370±0.01A      S–F 1.570±0.01A      O–S–O angle 129∘38′±30′ F–S–F angle 92∘47′±30′The S–O distance differs by −0.06A from the published electron diffraction value.

Measurements on stark lobes of the three 1→2 transitions of S32O2F2 gave a quantitative check of the assignment and a value of 0.228 Debye units for the dipole moment.
A Study of Selection Rules for Vibrational Spectra of Complex Crystals
Authors: Walnut Thomas H.
Published: January 2005

Relations are obtained for the expression of the dipole moment and polarizability matrices for a particular transition in a crystal, in terms of corresponding expressions for molecular or ionic groups within the crystal. The results show that, to the degree of approximation used (quadratic terms in the dipole moment or polarizability expansion and cubic terms in the potential energy), the only cause for the appearance of bands which would be forbidden for a given uncoupled complex ionic or molecular group is the alteration of the normal coordinates of these groups by vibrations of neighboring groups. It is also shown that the bands of fully allowed first overtones and binary combinations of frequencies that are not degenerate or near-degenerate in a unit cell have a shape that is approximately given from the distributions of frequencies that arise from lattice coupling.

As an incidental result, the dipole moment matrix elements for the first overtones and binary combinations arising from the cubic terms in the potential energy are given explicitly.
The Structure of the Tetrachloroethylene Molecule
Authors: Karle I. L. , Karle J.
Published: January 2005

The equilibrium distances and average amplitudes of vibration have been determined for the molecule C2Cl4 by the analysis of quantitative electron diffraction data. The results are listed in Table II.
An Electron Diffraction Investigation of Cyclooctatetraene and Benzene
Authors: Karle Isabella L.
Published: January 2005

The interatomic distances and their vibrational amplitudes have been determined for C8H8 and C6H6 by quantitative analysis of electron diffraction sector photographs. The D2d tub configuration, with the oblique C–C bonds longer than the horizontal ones, has been confirmed for C8H8. The interatomic distances involving hydrogen atoms have been evaluated.
Collisional Perturbation of Spin-Orbital Coupling and the Mechanism of Fluorescence Quenching. A Visual Demonstration of the Perturbation
Authors: Kasha Michael
Published: January 2005

A yellow color is produced when two colorless pure liquids, α-chloronaphthalene and ethyl iodide, are mixed, although no chemical reaction occurs. Spectroscopic examination reveals that the lowest singlet→triplet absorption band of the naphthalene molecule is greatly enhanced in intensity in the presence of the iodide, and that the development of this absorption band is responsible for the color effect. The process is interpreted in terms of a collisional perturbation of spin-orbital coupling in the π-electron orbitals of the naphthalene. The significance of this phenomenon in several topics in spectroscopy and chemistry is discussed. In particular, the molecular mechanism of heavy atom quenching of fluorescence by foreign species is resolved. A novel Beer's law anomaly is predicted for intercombinations.
Nuclear Electric Quadrupole Spectra in Solids
Authors: Bersohn R.
Published: January 2005

Recent experiments have demonstrated the feasibility of observing nuclear electric quadrupole interactions of widely varying magnitudes in solids. While these effects can often be observed in powdered samples, the most complete information is obtainable from the Zeeman pattern of a single crystal. To facilitate interpretation of these experiments, the nuclear spin energy levels are derived for different relative magnitudes of quadrupole interaction and external magnetic field. Besides the knowledge of the gradient of the electric field tensor, in principle, low frequency molecular rotation should be detectable by means of the quadrupole spectra.
The Properties of n-Butforane and Its Mixtures with n-Butane
Authors: Simons J. H. , Mausteller J. W.
Published: January 2005

The physical properties of n-butforane C4F10 were determined and also these mixtures of it with n-butane, C4H10. The properties of these two-component systems parallel very closely the system previously reported, n-pentforane and n-pentane. The necessity of a concept such as that of ``interpenetration'' is confirmed.
Cooperative Orientation Effects in Solutions
Authors: Barker J. A.
Published: January 2005

A general theoretical method for evaluating the effect on thermodynamic properties of cooperative orientation in solutions is developed. The theory is applied to the systems methanol+benzene, methanol carbon tetrachloride, and chloroform+ethanol. Theoretical curves for excess free energy of mixing, heat of mixing, and excess entropy of mixing as functions of composition are presented and are in reasonable quantitative agreement with experimental values for the first two systems and qualitatively similar to the experimental curves for the third. It is concluded that the method provides a useful approach to the theory of solutions of associated liquids in general.
Some Crystal Energetic Relationships in Oxysalts
Authors: Ramberg H.
Published: January 2005

A regularity exists between the heat of formation of alkali and alkaline earth oxysalts and the acidity and basicity of the oxides involved. The more basic an alkali or an alkaline earth oxide, the larger is the exothermic heat of formation of its oxysalts from the component oxides. Likewise, the more acidic the nonmetal oxide, the larger is the exothermic heat of formation of its salts from the component oxides. Although this is expectable in a general way, the regularity and consistency of these rules are rather surprising.

The exothermic heat of formation from the oxides of different oxysalts of the same metal increases when the nonmetal changes through the sequences: B, C, N, and Si, P, S, Cl. This is explained in light of the increasing covalent character (or increasing polarization) of the oxygen-nonmetal bonds through the same series of elements.

The exothermic heat of formation of polymerized oxysalts from the component oxides (borates, silicates, phosphates, pyrosulfates) is larger per equivalent than for the corresponding simple oxysalts. This is qualitatively explained as a result of the oxygen-nonmetal bond being less polarized or more ionic in a polymerized salt than in the nonpolymerized salt with the same central atom in the oxyanion.

The heat of salt formation per equivalent increases numerically when the metal changes from Li to Cs, or from Mg to Ra. This is related to the increase of the crystal energy of the corresponding metal oxides.
Rotational Isomerism as a General Property of Alkyl Nitrites
Authors: Tarte P.
Published: January 2005

The infrared and ultraviolet spectra of 15 alkyl nitrites were studied in the gaseous state. In the infrared, the O–N=O group is characterized by very strong absorption in the three regions 600, 800, and 1650 cm−1, corresponding to O–N=O bending, N–O stretching, and N=O stretching frequencies, respectively. The doubling of the characteristic frequencies and the temperature dependence of the bands of methyl nitrite are explained by rotational isomerism, which appears to be a general property of alkyl nitrites. The influence of the length, shape, and kind of the carbon chain on the frequencies and intensities of the characteristic bands has been studied. The intensity variation of the νN=O bands strongly suggests that the relative abundances of the two isomers vary widely from primary to secondary and tertiary nitrites, but depend only to a small extent upon the length and shape of the carbon chain. Application of this property to the diagnosis of primary, secondary, or tertiary alcohols is suggested.

The uv spectra consist essentially of two systems of diffuse bands (and not of one, as stated by previous workers), whose relative intensities vary in the same manner as the relative abundances of the two rotational isomers. The two systems of bands are accordingly assigned to these rotational isomers. This hypothesis has been checked by a study of the temperature dependence of the intensity of the bands.
Solutions of Some Problems Concerning Long Random Coils
Authors: Hollingsworth C. A.
Published: January 2005

The problem of random flights in boundary value form is used to determine certain probabilities related to the probability that a long random coil passes within a given distance of one or more given points.
Semilocalized Orbitals. IV. Relationship of n-Center Orbitals, Two-Center Orbitals, and Bond Properties
Authors: Mueller Charles R.
Published: January 2005

The relationship between n-center orbitals, two-center orbitals, and bond properties is discussed from the standpoint of atomic, molecular, and semilocalized orbital theory.

The necessary restrictions on the transformation from the more general n-center to the two center orbitals is also discussed and a practical computational method for molecular problems is suggested.

The relationship of the atomic and molecular orbital theories of the excited electronic states of molecules is also investigated.
The Compressibility of and an Equation of State for Gaseous Neopentane
Authors: Beattie James A. , Douslin Donald R. , Levine Samuel W.
Published: January 2005

The compressibility of gaseous neopentane (2–2-dimethyl propane) has been measured from 160.60°, the critical temperature, to 275° over a density range from 1 to 7 mole per liter, the maximum pressure being about 300 atmos. The constants of the Beattie-Bridgeman equation of state for the gas phase are R=0.08206, A0=23.3300, a=0.15174, B0=0.33560, b=0.13358, c=400×104 in units of normal atmos, liter per mole, °K(T°K=t°C+273.13), the molecular weight being taken as 72.0924 g per mole. The second virial coefficients were determined graphically at each temperature.
The Reaction of Hg(3P1) with Ethylene
Authors: Darwent B. deB.
Published: January 2005

The reaction of Hg(3P1) with ethylene at room temperature has been re-investigated. Special attention was paid to the effects of the concentrations of ethylene and mercury on the reaction velocity. The results are in general agreement with a mechanism which requires the excited ethylene, produced initially, to decompose both in the gas phase and on the wall. The results are also compatible with the suggestion that a significant fraction of the quenching collisions between ethylene and Hg(3P1) leads to the formation of metastable (3P0) atoms.
The Reaction of Cd(3P1) with Propane at Low Conversion
Authors: Agius P. , Darwent B. deB.
Published: January 2005

The reaction of Cd(3P1) with propane has been investigated at 300°C under such conditions that the rates of production of hydrogen and methane are independent of time. The quantum yield of hydrogen production, when corrected for incomplete quenching, is close to unity and is approximately independent of the substrate pressure. The production of methane can be accounted for by the decomposition of propyl radicals. The ratio CH4/H2 increases with decreasing pressure of propane; if this ratio varies as Ia−½ (as is the case when the methyl radicals are produced by the thermal decomposition of propyl radicals), the increase may be ascribed to the decreasing absorbed intensity at lower pressures.
Kinetics of Decomposition of Nitric Oxide at Elevated Temperatures. II. The Effect of Reaction Products and the Mechanism of Decomposition
Authors: Wise Henry , Frech Maurice F.
Published: January 2005

The effects of nitrogen and oxygen on the kinetics of decomposition of nitric oxide have been investigated. In the temperature region in which the heterogeneous mechanism prevails (at T<1000°K) the presence of nitrogen has a marked retarding influence on the reaction rate of nitric oxide due to poisoning of the surface. On the other hand, the addition of oxygen results in a marked increase in the rate of decomposition of nitric oxide over the entire temperature range studied. At high concentrations of oxygen the following empirical rate expression obtains, −d[NO]dt=ka[NO]2+kb[NO][O2]12,with an activation energy of 78.2 kcal for the rate-determining step. It is apparent therefore that the decomposition of nitric oxide is autocatalytic. On the basis of these experimental observations a mechanism is proposed involving a chain propagated by the atomic species formed in the reaction.
Heat Capacity, Gas Imperfection, Infrared Spectra, and Internal Rotation Barriers of Ethyl Alcohol
Authors: Barrow Gordon M.
Published: January 2005

The vapor heat capacities of ethyl alcohol have been measured, as a function of pressure, at 368, 422, and 476°K. From the variation of the heat capacity with pressure, together with vapor densities calculated by the Clapeyron equation, an equation of state for ethyl alcohol has been obtained. This equation has been used to extrapolate the measured heat capacities to the ideal gas state and likewise to correct the observed entropy.

The infrared spectra of vapor C2H5OH, C2H5OD, and liquid C2H5OD are presented and a vibrational assignment is obtained which is sufficiently reliable for the statistical calculation of the thermodynamic properties.

Comparison of the observed and statistically calculated heat capacities and entropies shows that, with a barrier to internal rotation of the CH3 group of 3000 calories, the rotation of the OH group is hindered by a barrier between 0 and 1200 calories. Most satisfactory agreement is obtained for CH3 and OH barriers of 3300 and 800 calories, respectively. Furthermore, comparison of the observed and calculated equilibrium constants for the reaction C2H4(g)+H2O(g)⇌C2H5OH(g)supports the selection of fundamental frequencies and internal rotation barriers.
Separation of the Absorption Spectra of NO2 and N2O4 in the Range of 2400–5000A
Authors: Hall T. C. , Blacet F. E.
Published: January 2005

The individual absorption coefficient curves of NO2 and N2O4, separated by means of a mechanical analog differential analyzer are presented. Beer's law is assumed to be applicable to the system. The range 2400–5000A is covered. A discussion of the apparently continuous nature of the N2O4 absorption is included.
Crystalline Field in Chrome Alum
Authors: Kleiner W. H.
Published: January 2005

A calculation is made to test the detailed applicability of the crystalline field approximation for describing magnetic properties of chrome alum.

The theoretical susceptibility formula of Schlapp and Penney represents the experimental susceptibility as a function of temperature reasonably well provided the parameter Dq, which gives a measure of the interaction between the crystalline field and the paramagnetic ion, is arbitrarily chosen to give the best fit. Here Dq is calculated; a model of the surroundings of the Cr+++ ion is used to determine the crystalline field. The calculated Dq is in poor agreement with experimental values, from which it is inferred that the interaction between the Cr+++ ion and its surroundings is so strong that the crystalline field approximation is inadequate to give detailed agreement with experiment. The results are expected to apply to other hydrated paramagnetic salts of the iron group.
Intermolecular Forces in Acetone and Methyl Alcohol
Authors: Myers Vernon
Published: January 2005

The long-range intermolecular forces between acetone molecules and between methyl alcohol molecules are computed from optical dispersion data and dipole moments, and the short-range repulsive forces are estimated from second virial coefficients. The experimental second virial coefficients for (CH3)2CO and CH3OH are those of Lambert and his co-workers (Proc. Roy. Soc. (London) 196A, 113 (1949)).
The Raman Spectrum, Structure, Force Constants, and Thermodynamic Properties of Bromine Pentafluoride
Authors: Stephenson C. V. , Jones E. A.
Published: January 2005

Using a Raman tube made of the plastic polychlorotrifluoroethylene, the Raman spectrum of bromine pentafluoride has been obtained. A method has been developed for making polarization measurements when Raman tubes constructed of this plastic are used. The spectrum of bromine pentafluoride has been correlated with a tetragonal pyramid configuration with symmetry C4v. Force constants were calculated using the Wilson FG Matrix method. The thermodynamic functions for BrF5 were calculated for temperatures ranging from 313.7°K to 1500°K, using the rigid rotator, harmonic oscillator approximation.
Absorption Studies of the Vapors of the Three Isomeric Picolines in the Near Ultraviolet
Authors: Rush J. H. , Sponer H.
Published: January 2005

Studies of the near ultraviolet absorption spectra of α-, β-, and γ-picoline vapor have been made in low and medium dispersion. Conclusive evidence is found for two electronic transitions in the vicinities of 35500 and 38500 cm−1. The former transition is interpreted as an allowed A1—B2 transition resulting from the excitation of an sp2 nonbonding electron of the nitrogen atom into the first unfilled π-orbital of the ring. The latter transition is considered an allowed A1—B1 transition resulting from the excitation of a π ring electron. The A1—B2 system exhibits narrow headless bands similar to the first absorption bands in pyridine. It is of weak intensity comparable to that of the forbidden A1g—B2u transition in benzene. The A1—B1 system, which is much stronger, consists of broad diffuse bands. There is evidence that this system may be overlapped by another transition in β-picoline.