bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermodynamic Properties of Nonstoichiometric Urania-Thoria Solid Solutions
Authors: Aronson S. , Clayton J. C. 
Published: January 2005

A solid state electrochemical technique has been used to obtain thermodynamic information on uraniathoria solid solutions of compositions UyTh1−yO2+x with values of y of 0.9 to 0.3 and values of x of 0.02 to 0.16. The electrochemical cells were of the type Fe,FeO | (ZrO2+CaO) | UyTh1−yO2+x, Pt. Measurements were made at temperatures of 1150–1350°K.
Partial molar free energies, entropies, and enthalpies of solution of oxygen in the solid solutions were calculated. The partial molar free energy decreases negatively with increasing thorium content for thorium concentrations greater than 30 atomic percent. The partial molar entropy increases negatively with increasing oxygen content or with increasing thorium content.
The experimental results are discussed in connection with a mechanism of interstitial solution of oxygen ions in the fluorite lattice. A thermodynamic equation for the entropy is developed which gives semiquantitative agreement with the experimental data.
Chemically Induced Vibrational Excitation: Hydroxyl Radical Emission in the 1–3 Micron Region Produced by the H+O3 Atomic Flame
Authors: Garvin David , Broida H. P. , Kostkowski H. J. 
Published: January 2005

A detailed investigation has been performed in the 1- to 3-μ wavelength region on the radiation emitted by the hydroxyl radical from a low-pressure flame of ozonized oxygen and atomized hydrogen. Wavelengths and photon intensities have been obtained for about 300 lines in the OH vibration-rotation bands V—V—ΔV where ΔV=3, V=9 to 5, and for ΔV=2, V=9 to 2. Relative photon band intensities have been determined from the overdetermined set of data by a method of successive approximations using an IBM 650 computer. Dipole moment parameters have been calculated using the above data and Morse oscillator transition probabilities.
Approximate rotational and vibrational Boltzmann distributions exist with an average rotational ``temperature'' of 560°K for the P branches, 460°K for the R and Q branches, and a vibrational ``temperature'' of 9250°K for the ΔV=2 and 3 bands. The absence of radiation from levels V&gt;9 confirms the nonthermal character of the excitation and its dependence on the energetics of the reaction O3+H→OH+O2. Moreover, flux calculations based on the assumption that in this case collisional deactivation transition probabilities are proportional to the radiation probabilities show that there is an appreciable OH production in all levels V≤9 and the main flux of OH through any population level is via ΔV=1 transitions. Possible causes for the large changes in line intensity with pressure and smaller but significant changes with flows or concentrations are discussed.
Infrared Detection of the Formyl Radical HCO
Authors: Ewing George E. , Thompson Warren E. , Pimentel George C. 
Published: January 2005

The photolysis of HI, DI, HBr, and DBr suspended in solid CO at 20°K is described. The formyl radical, HCO or DCO, is produced, as shown by broad absorptions in the visible spectral region (6695, 6352, 6052, 5789, 5548, 5330, 5102 A) which correspond to absorptions of gaseous HCO. Infrared absorptions of HCO (at 1860 and 1091 cm—1) and of DCO (at 1860 and 856 cm—1) provide a basis for discussing the chemical bonding of this free radical, and for calculating its thermodynamic properties.
These experiments, the first infrared detection of a triatomic free radical by the matrix isolation method, depend upon reactivity of the matrix, possibly eliminating difficulties of the cage effect.
Forbidden Band Systems in Nitrogen. III. The Y 3Σu—←X 1Σg+ System in Absorption
Authors: Wilkinson P. G. 
Published: January 2005

Four bands of the Y 3Σu—←X 1Σg+ system of nitrogen have been observed in absorption in a path of 3.4 meter-atmospheres at 1518 A (0–0), 1484 A (1–0), 1453 A (2–0) and 1423 A (3–0). These bands consist of an unresolved Q branch (QQ, QP, QR), and SR and 0P branches.
From a comparison of the experimental and calculated intensity distribution, it is shown that the upper state is 3Σu— rather than the alternative assignment of 3Δu.
It is further shown that the Y 3Σu— state is identical with the upper state of certain infrared bands recently found in the active nitrogen afterglow. Those bands are thereby identified as Y 3Σu—→B 3Πg. The upper state was designated ``Y'' by Kistiakowsky and Warneck.
The constants of Y 3Σu— as obtained here are: ωe=1517.69 cm—1; ωexe=12.22 cm—1; Be=1.472 cm—1; αe=0.0161 cm—1; T00=65850.6 cm—1; re=1.2788 A.
The transition Y 3Σu—←X 1Σg+ receives intensity from perturbations of Y 3Σu— by 1Σu+ and 1Πu states lying at higher energies.
Electronic Structure of Carbon Monoxide
Authors: Brion Hélène , Moser Carl 
Published: January 2005

The LCAO—MO SCF orbitals for carbon monoxide have been calculated with 1s, 2s, and 2p Slater atomic functions, using best atom (Roothaan) exponents. All atomic integrals have been calculated. While all the orbitals are orthogonal, the inner shells have been given a fixed form. The calculated binding energy (using these SCF orbitals for the molecular energy and the same atomic functions for atomic energy) is about 40% of that observed. A limited configuration interaction calculation gives about 55% of the observed binding energy. Both the single determinant and the CI wave function predict a dipole moment which is in agreement with the observed sign C—O+, but the error in magnitude is rather large. The atomic populations suggest the sign of the dipole moment to be C+O—, in agreement with Malone's rule.
The ionization energies have been calculated and the agreement with experiment is very satisfactory. Some of the observed lower electronic transitions can be understood by using single configurations constructed from these SCF orbitals, but, before a more complete analysis of the spectrum can be attempted, it may be necessary to introduce atomic functions from the M shell.
Interactions between Molecules Adsorbed on a Surface
Authors: Sinanoğlu Oktay , Pitzer Kenneth S. 
Published: January 2005

The intermolecular potential energy between two inert gas molecules is considerably altered when these molecules are next to a solid surface as in physical adsorption. The change in the interaction is evidenced by the additional long-range repulsion that is often observed between the molecules of a monolayer and also by the additional attractions that must play a role in multilayer formation.
In this article, the two-molecule-surface potential is derived from quantum mechanical third-order perturbation theory. It is shown that this potential consists of two parts just as the energy giving the van der Waals attraction of a single molecule to a surface does. The first part exists only when the surface has a net electrostatic field and this is equivalent to the classical polarization effect. The second part arises from the fluctuations of the surface fields and is of the same origin as the dispersion forces. The third-order energy, i.e., the new intermolecular interaction caused by the surface, is directly related to the zero-coverage heat of adsorption and except for this experimental quantity, the results do not require specific assumptions about the surface. Thus, the theory is applicable to either metal or insulator surfaces. When both the two-molecule-surface and the one-molecule-surface interactions are available experimentally (for example, from the application of virial coefficients treatment in physical adsorption) the electrostatic field of the surface can be estimated.
The fluctuation or dispersion part of the third-order energy is shown to yield a repulsion between two molecules in a monolayer that amounts to 20–40% of the gas phase Lennard-Jones potential minimum ε0. The same energy yields an additional attraction of about 10–20% of ε0 when the two molecules are on top of one another as in multilayer formation. The theory is applicable also when more than two molecules at a time need be considered on the surface.
Thermodynamic Excess Functions for Electrolyte Solutions
Authors: Friedman Harold L. 
Published: January 2005

A system of excess functions is developed for electrolyte solutions and other solutions with an essentially unsymmetrical solvent-solute relation. These new functions vanish for a solution whose practical (molal scale) osmotic coefficient is unity at all compositions, temperatures and pressures. The use of these excess functions offers some advantages over other methods of comparing Mayer's ionic solution theory with experiment, of representing the properties of solutions of single or mixed electrolytes, and of making qualitative interpretations of the molecular basis of thermodynamic properties.
Graphs showing the ionic-strength dependence of the excess free energy, excess enthalpy, excess entropy, and excess volume are given for several aqueous solutions of single electrolytes up to 6 molal. Experimental values of the cluster integral sum, the characteristic function of the Mayer theory, have also been calculated. The concentration dependence of this function is very similar to that of the excess free energy.
Madelung Constant for K2SO4(II)
Authors: Wood Robert H. 
Published: January 2005

The Madelung constants of NaCl, CsCl, and K2SO4 have been calculated with the aid of a digital computer.
The method of summing over neutral shells of atoms with each shell being composed of unit cells is used. This method allows the presence of surface dipole moments (de Boer effect) to be ignored. The results for K2SO4 allow the calculation of the Madelung constant as a function of the charge on the oxygen (Mδ=6.922+0.36ε).
Induction Studies in Several Groups of Halogen-Containing Organic Compounds by Their Cl35, Br79, or Br81 Pure Quadrupole Resonance Spectra
Authors: Hooper H. O. , Bray P. J. 
Published: January 2005

Induction studies have been carried out in several groups of halogen-containing organic compounds by means of the halogen pure quadrupole spectra. In several straight-chain compounds inductive effects have been examined as a function of the length of the chain in some monohalogenated-paraffin hydrocarbons and as a function of the number of carbon atoms separating halogen atoms attached to either end of dihalogenated-paraffin hydrocarbons. The effects of the hybridization of the carbon atom have also been examined in some aliphatic hydrocarbons. Chlorine pure quadrupole resonance frequencies from chlorine atoms bonded to atoms other than carbon, such as silicon, nitrogen, and sulfur, have been measured, and the effects of these different atoms upon the Cl35 resonance frequencies are qualitatively discussed.
Inductive effects have also been examined in different groups of aromatic compounds. The inductive effect in several chlorobenzyl compounds is found to be about ¾ of what it is in the corresponding chlorobenzene compounds as determined from a comparison of the Cl35 resonance frequencies. Definite discrepancies have been observed between the Cl35 spectra obtained from several aromatic compounds which have molecular structures similar to anthraquinone and the Cl35 frequencies that can be predicted from data obtained from chlorobenzene compounds and Hammett σ values.
Employing the linear relationship between Cl35 resonance frequency and Hammett σ values, several Cl35 frequencies were predicted and compared to the measured frequencies in some chlorobenzene compounds. Some unknown σ values have also been predicted. A linear relationship between Br81 resonance frequencies and Hammett σ values has been developed from measured bromine quadrupole frequencies. Several halogen frequencies from some unrelated compounds have been measured and are tabulated in this paper.
Paramagnetic-Resonance Studies of Irradiated High-Density Polyethylene. II. Effect of Irradiation Dose on the Radical Species Trapped at Room Temperature
Authors: Lawton Elliott J. , Balwit J. S. , Powell R. S. 
Published: January 2005

The previous paper presented a study of the radical species in irradiated Marlex-50 at low dose levels. This paper extends that study to a level of 4000 megaroentgens. The kind and relative number of each radical trapped at room temperature (RT) depends on the degree and tightness of the crystalline and crosslinked fractions during irradiation. At least two of three distinct species, having different hyperfine structures (six-, five-, and a single-line) are present in varying concentrations at all doses. The six- and five-line radicals are trapped in the crystal, whereas the single-line radical is trapped in the highly crosslinked medium. During irradiation at RT and liquid-nitrogen (LN) temperature, the crystal is not as effective in trapping the six-line radical as in the absence of irradiation. At 640 megaroentgens the six-line radical does not survive during irradiation at RT, leaving the five- and single-line radicals above this level. The single-line radical appears at 320 megaroentgens and increases until at 3000 megaroentgens, where crystallinity is zero, it accounts for about 70% of the total.
Heating the irradiated samples causes all radicals to disappear; the ``extinction temperatures'' for the six-, five-, and single-line radicals were 90°, 135°, and about 250°C, respectively. The relative effectiveness of the preirradiated annealed samples compared to the nonirradiated Marlex-50 in trapping radicals at RT was 0.5 for the 20-megaroentgen, 1.0 for the 320-megaroentgen, and 1.4 for the 4000-megaroentgen preirradiated material. There is evidence in the uv spectrum for conjugated double bonds in the highly irradiated samples. It is proposed that the single-line radical is initially formed adjacent to the conjugated sequence and then becomes trapped within the sequence by resonance. The radical could be represented as –CH=CH–CH=CH–CH– lim ←·→CH=CH–CH=CH–..
Dissolution Kinetics at Dislocation Etch Pits in Single Crystals of Lithium Fluoride
Authors: Ives M. B. , Hirth J. P. 
Published: January 2005

The kinetics of dissolution at dislocation etch pits on lithium fluoride in dilute aqueous solutions of ferric fluoride were studied by interferometric observations on etched surfaces.
The effects on dissolution of the variables time, temperature, undersaturation, crystal perfection, and crystal orientation were determined. It was found that dissolution was consistent with the mechanistic theories of crystal dissolution involving dissociation of lithium fluoride from monomolecular ledges on close-packed surfaces and subsequent diffusion into solution, if a time-dependent adsorption of inhibitor at the receding ledges is invoked.
Proton-Magnetic-Resonance Study of Barium Bromide Monohydrate
Authors: McGrath J. W. , Silvidi A. A. 
Published: January 2005

The proton-magnetic-resonance doublets were obtained for rotation of the crystal around its c axis. From these data, the proton-proton separation was computed to be 1.56±0.02 A. The hydrated water molecule was found to lie in one orientation whose proton-proton axis makes direction angles of α0=89±1°, β0=1±1°, and γ0=90±6°, measured from the positive a, b, and c crystallographic axes, respectively. This orientation fits well into the crystal structure and indicates that the complex, BrI— —H–O–H— —BrII, exists.
Line widths range from 6.5 to 4.2 gauss and show a correlation with T1 as a function of orientation. Observation was necessarily made with some saturation.
A new effect, an asymmetry of line areas in the doublets, was observed for narrow ranges near two crystal orientations. The two orientations were symmetrically close to that for which the proton-proton line was parallel to the external magnetic field. It may be due to crossing of the barium quadrupole resonance frequencies over the magnetic-resonance frequencies of the protons.
Diamagnetism as a Test of Wave Functions for Some Simple Molecules
Authors: Banyard K. E. 
Published: January 2005

A theoretical study is made of the diamagnetism of some simple molecules in a gaseous form, attention being mainly devoted to the ``neon-like'' series Ne, H2O, NH3, and CH4. In this way an attempt is made to gain insight into the way in which the radial electron density distribution within the molecules is influenced, firstly, by the allowance of exchange effects and secondly, by the inclusion of angular terms which must be accounted for in any ``physically real'' description of the electron density.
In general, it is found that exchange effects cause the radial density distribution to contract, while the inclusion of angular terms results in the subsequent radial electron density becoming more diffuse.
Spectral Solvent Shift. I. Paraffin Hydrocarbon Solvent Interactions with Polynuclear Aromatic Hydrocarbons
Authors: Weigang O. E. 
Published: January 2005

The electronic shifts for 11 ultraviolet transitions of the chromophores naphthalene, phenanthrene and the polar aromatic hydrocarbon, azulene, have been observed in a series of 17 paraffin hydrocarbon solvents from isopentane to n-tridecane. The contribution to the shift of branching and cyclization of solvent molecules has been observed by including the five structural isomers of hexane, 2,2,4-trimethylpentane and 2,2,5-trimethylhexane together with the cyclo- and methylcyclopentanes and hexanes.
The statistical approach is used to interpret the electronic shifts in terms of interbond potentials and the solvent radial distribution function and is compared to the McRae extension of the Bayliss solvent shift theory. Dispersive type potentials suffice to account for the frequency shifts of transitions, except the 1Lb transition of azulene which shifts to the blue from the vapor to hydrocarbon solutions. The behavior can be accounted for by a change in the static dipole moment of azulene on excitation, a phenomenon predicted by quantum mechanical calculations on the molecule.
Dynamics of the Quasi-Linear Molecule
Authors: Thorson Walter R. , Nakagawa Ichiro 
Published: January 2005

Calculations of energy levels, eigenfunctions, dipole transition moments, and other significant properties have been made for a phenomenological model of a two-dimensional harmonic oscillator with a superposed barrier at the minimum of the harmonic potential. A high-speed electronic digital computer was employed. The method of calculation does not involve perturbation theory and converges rapidly for all barrier heights. The problem concerns the behavior of the degenerate bending vibration of a linear triatomic molecule, for example, when a potential barrier is introduced at the linear configuration. In the limit of a high barrier, the motion is that of a ``bent'' molecule with rotational motion superposed on the bending vibration about the minimum of potential energy. Results for moderate to low barriers, and those for anharmonic vibration in a well with no barrier, show that the rigid classification of molecules as ``linear'' or ``bent'' is not possible in some cases and that the intermediate case of the ``quasi-linear'' molecule must be considered. The dynamical behavior of such anharmonic motion and its interaction with other vibrations have been investigated, and the primary identifying characteristics of the quasi-linear molecule delineated.
The analytical method of solution used has also been applied successfully to the one-dimensional barrier problem.
Effect of Pressure on the Spectra of Rare Earth Ions in Crystals
Authors: Keating K. B. , Drickamer H. G. 
Published: January 2005

The effect of pressure to 180 000 atm has been measured on the absorption spectra of crystalline rare earth ions. The effects observed include:
(1) An increase of intensity due to increased mixing of 5d and 4f orbitals in the excited state due to an increase of the mixing potential with decreased interionic distance.
(2) Small shifts accompanied by increases in half-width. Except for the shifts of 3P0, 3P1, and 3P2 levels of Pr+3, these can be accounted for by an increase in the splitting of the individual levels due to intensification of the crystal field.
(3) Changes in shape of several of the bands, possibly due to changes in occupation of the various states which make up the bands.
Proton Magnetic Resonance Studies of Structure, Diffusion, and Resonance Shifts in Titanium Hydride
Authors: Stalinski B. , Coogan C. K. , Gutowsky H. S. 
Published: January 2005

Measurements of the proton magnetic resonance at ∼26.9 Mc in titanium hydride samples, ranging in composition from TiH1.61 to TiH1.97, have been made in the temperature range from —196° to about 200°C. The second moment of the proton resonance at the lower temperatures shows that the hydrogen atoms are randomly distributed among the lattice sites which are located tetrahedrally with respect to the titanium atoms. Self-diffusion of the hydrogen atoms narrows the proton resonance above room temperature. The temperature dependence of the correlation frequency for the proton motions, obtained from the linewidths, leads to diffusional activation energies which increase with hydrogen content from 9.4 kcal/g atom for TiH1.607 to 10.2 for TiH1.923. Moreover, the diffusion rate is directly proportional to the number of unfilled tetrahedral holes in the metallic lattice, which indicates that the self-diffusion takes place via a vacancy mechanism.
Proton resonance shifts to higher applied magnetic fields were observed. They were measured at room temperature for all specimens and were found to increase from 0.01% for TiH1.607 to about 0.032% for TiH1.969. For these two extreme compositions, the temperature dependence of the shift was measured between —95°C and 190°C and was found to be similar to the bulk susceptibility, the shifts for TiH1.969 exhibiting an anomaly at about 13°C as does the susceptibility. These results are interpreted semiquantitatively in terms of exchange interactions which pair spins of electrons in the conduction band with those of electrons localized on the hydrogen. The results suggest that the hydrogen is held in the lattice by a combination of covalent and ionic bonding, the latter involving a net positive charge on the hydrogen. The general importance of exchange interactions in intermetallic compounds is commented upon.
Electronic Structure, Spectra, and Magnetic Properties of Oxycations. III. Ligation Effects on the Infrared Spectrum of the Uranyl Ion
Authors: McGlynn S. P. , Smith J. K. , Neely W. C. 
Published: January 2005

A series of uranyl complexes KxUO2Ly(NO3)2, where L is the variable ligand (or ligands), has been prepared; it has been shown that a ligand series may be defined using the antisymmetric stretching frequency of the uranyl entity, and this series exhibits a remarkable parallelism with the spectrochemical series defined by Δ in octahedral complexes of transition metals of the 1st and 2nd series. This parallelism has been rationalized using a mixed ligand field theory in which the uranyl ion is considered subject to bonding with ligands which are arranged hexagonally in a plane equatorial to the O–U–O axis. It is shown that the large changes of ν3 and ν1 are due primarily to electron population of the φu and δu atomic orbitals of uranium. Such population is physically equivalent to the reductions AmO2+ +→AmO2+ and NpO2+ +→NpO2+, which cause a decrease of approximately 100 cm—1 in ν3. It is further shown that Δν̄3 = — electrostatic effect — σ(L→M) — π(L→M) ± π(M→L), where in the last term the plus sign is the more probable, and the results obtained have been rationalized using this equation.
Some evidence in favor of linearity of the UO2+ + has also been induced, and a general criterion for distinguishing the difficulty observable ν1 has been reestablished. It has also been shown, although not discussed extensively, that the stability of uranyl complexes should increase, roughly as ν̄3 (or ν̄1) decreases. The discussion of similar effects in vanadyl, titanyl, chromyl, and other oxycations has been deferred to a later time.