bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron Conduction in Charge-Transfer Molecular Crystals
Authors: Menefee E. , Pao Yoh-Han
Published: January 2005

Molecular crystals consisting of strong electron donors and strong electron acceptors in ordered array often possess electronic properties which are not found in other types of organic solids. Molecular orbital calculations have been carried out for the triethylammonium-(tetracyanoquino dimethane)2 crystal. The LCAO-MO method combined with a crystal-field splitting calculation resulted in a reasonably accurate value for the activation energy observed for electron conduction. On a basis of the results of this calculation, one would conclude that this type of organic solid should not be expected to exhibit the properties of conventional inorganic semiconductors. However, the results do provide a basis for some hypotheses concerning electron conduction processes and possible photoconduction mechanisms in these solids.
Theory of Polyhedral Molecules. III. Population Analyses and Reactivities for the Carboranes
Authors: Hoffmann Roald , Lipscomb William N.
Published: January 2005

Population analyses of the molecular orbitals of the polyhedral carboranes, BN—2C2HN, are computed. All the geometrical isomers of the trigonal, tetragonal, pentagonal bipyramid, and the icosahedron geometries are analyzed, and predictions made of the reactivities of these compounds and their derivatives. A comparison is also made between an LCAO-MO charge distribution and one derived from the three-center bond formalism.
Infrared Absorption by Carbon Monoxide at High Temperature
Authors: Davies William O.
Published: January 2005

The absorption of infrared radiation by carbon monoxide has been measured at wavelengths of 4.60, 4.67, and 4.72 μ for temperatures from 1160° to 2300°K. The test gas was heated to the desired temperatures by shock compression. The carbon monoxide optical density varied from 4 to 11 atm-cm; total gas pressures ranged from 1.40 to 3.60 atm. Absorption coefficients, presented as averages over slitwidth and total pressure, varied from 0.091 to 0.040 atm—1 cm—1 at 4.60 μ, 0.057 to 0.031 atm—1 cm—1 at 4.67 μ, and 0.065 to 0.026 atm—1 cm—1 at 4.72 μ, with higher values corresponding to lower temperatures. A pressure dependence of absorption was observed and an empirical correction assuming the logarithm of transmission proportional to the fourth root of total pressure was found to render Beer's law plots linear. Absorption coefficients were calculated by averaging over slitwidth an expression requiring a knowledge of the pressure dependence of integrated absorption. A comparison of these calculations with the observed values indicates quantitative agreement for 4.60 and 4.72 μ, and qualitative agreement for the temperature dependence of absorption at 4.67 μ.
Infrared Spectra of Metal Chelate Compounds. VIII. Infrared Spectra of Co(III) Carbonato Complexes
Authors: Fujita Junnosuke , Martell Arthur E. , Nakamoto Kazuo
Published: January 2005

The infrared spectra of twenty Co(III) carbonato complexes have been measured in a range between 4000 and 300 cm—1. Normal coordinate treatments were made with a model based on the unidentate and bidentate forms of the 1:1 (metal/ligand) complex. The theoretical band assignments and force constants obtained by these calculations confirm the validity of the previous qualitative conclusions based on the differences of symmetry and the frequency shifts of the unidentate and bidentate complexes. The Co(III)-O stretching bands were located at 440∼380 (antisymmetric) and at 400∼350 (symmetric) for the bidentate complexes, and at 360∼340 cm—1 for the unidentate complexes.
Apparent Molar Volumes of Salts and Metals In Liquid Ammonia at 0°
Authors: Gunn Stuart R. , Green LeRoy G.
Published: January 2005

Apparent molar volumes of some metals and salts in dilute liquid ammonia solutions at 0° have been measured with a direct-mixing dilatometer. There is little volume change involved in dissociation of diamagnetic metal species, but a large volume decrease results from dissociation of ion-pairs in salt solutions. Volumes are estimated for single ions and the solvated electron.
Use of a Pseudopotential in Color Center Calculations
Authors: Patterson J. D.
Published: January 2005

The use of a pseudopotential to take account of orthogonality of wave functions in color center calculations is discussed. It is concluded that the theoretical justification for its use is shaky. Preliminary calculations are reported which seem to support the view that a pseudopotential leads to an inaccurate effective Hamiltonian.
Study of Electronically Excited Hydroxyl Radicals in the H + O3 Atomic Flame
Authors: Broida H. P.
Published: January 2005

Ultraviolet emission of the A 2Σ+→X 2Πi transition of OH has been observed in low-pressure flames of hydrogen atoms and ozone. In these flames, at pressures near 1 mm Hg, the intensity of this uv emission was found to be directly proportional to the square of the intensity of the rotation-vibration bands in the electronic ground state, 2Πi. Under similar conditions, reactions of hydrogen atoms with oxygen atoms or with hydroxyl radicals were found to give too little emission to account for the observed radiation. It is concluded that collisions of two vibrationally excited OH radicals, 2Πi, lead to the electronically excited radicals, 2Σ+. Approximately 500 photons are emitted by all the vibrationally excited radicals (v=1 to 9, 2Πi) for each photon emitted in the electronic transition A 2Σ+→X 2Πi. Steady-state partial pressures of vibrationally excited OH, 2Πi, are estimated to be 10—7 mm Hg for a total flame pressure of 1 mm.
Vapor Pressures of Scandium, Yttrium, and Lanthanum
Authors: Ackermann R. J. , Rauh E. G.
Published: January 2005

The vapor pressures of scandium, yttrium, and lanthanum were measured by the effusion method with a vacuum balance, and the heats of vaporization were measured with a mass spectrometer. The data are represented by Scandium:logp (atm)=(5.44±0.07)−(17020±90)/T,Yttrium:logp (atm)=(5.59±0.07)−(19950±90)/T,Lanthanum:logp (atm)=(6.08±0.09)−(21940±150)/T.The errors quoted are standard deviations. The heats of vaporization at temperature are 77.9±0.4, 91.3±0.4, and 100.4±0.7 kcal mole—1 for scandium, yttrium, and lanthanum, respectively, and the corresponding entropy changes are 24.9±0.3, 25.6±0.3, and 27.8±0.4 eu.
Semiconductive Properties of Tetracyanoethylene Complexes and Their Absorption Spectra
Authors: Kuroda H. , Kobayashi M. , Kinoshita M. , Takemoto S.
Published: January 2005

The absorption bands characteristic of the solid molecular complexes of tetracyanoethylene are attributed to the charge transfer interaction between tetracyanoethylene and donor molecules.

In the complexes with polycyclic aromatic hydrocarbons the energy gap associated with the semiconductivity agrees well with the energy of the charge transfer excitation in the crystalline state, while the former is much smaller than the later in the complexes with polymethylbenzenes and azulene.
Microwave Saturation in Radiation-Induced Free Radicals
Authors: Simmons J. A.
Published: January 2005

An account is presented of some effects arising from the weakness in coupling between radiation-induced free radicals and the surrounding lattice. The electron spin resonance technique was employed to investigate irradiated amino acids, and the results obtained are compared with theoretical predictions. It was found that a mechanism similar to the inhomogeneous broadening described by Portis was occurring, and the spin-lattice relaxation times were of the order of 10—5 seconds.
Effect of Dispersion Interaction on Nuclear Magnetic Resonance Shifts
Authors: Howard Bentz B. , Linder Bruno , Emerson Merle T.
Published: January 2005

The continuum model treatment of long-range intermolecular forces is applied to the effect of dispersion interaction on NMR shifts. The theory is applied to infinitely dilute solutions of nonpolar molecules in nonelectrolytes and to pure gaseous substances. Calculated shifts are in semiquantitative agreement with the experimental values; the general trends are accurately predicted. Polar solvents show no unusual behavior. Several empirical relations, previously proposed, are derived and discussed.
Theory of the Anomalous Heat Capacity in Solid Hydrogen and Deuterium at Low o-Hydrogen and p-Deuterium Concentration
Authors: Orttung William H.
Published: January 2005

The theory of the anomalous heat capacity for low concentrations of ortho hydrogen in the solid state has been extended by a calculation based on the angular potential energy between adjacent molecules. The effects included were (1) the chemical or valence energy, (2) the electrostatic quadrupole-quadrupole energy, and (3) the inverse sixth-power dispersion energy. The expression used for the first type of interaction was derived theoretically by de Boer, while gas-phase experimental parameters were used to evaluate the second two types of interaction in connection with a theoretical estimate of the anisotropy of polarizability of the hydrogen molecule.

It was found that only electrostatic quadrupole-quadrupole interactions had to be considered at one atmosphere, but at higher pressures, the valence forces became important. The case of three ortho hydrogen molecules in a row was also treated in the quadrupole approximation. The heat capacity predicted by this model was somewhat different from that predicted for isolated ortho-ortho pairs. The theory was compared with available one atmosphere data on ortho hydrogen and para deuterium at low concentrations in the solid. The results depend not only on the total ortho concentration but also on the relative concentrations of isolated ortho molecules, isolated pairs of ortho molecules, and more complicated configurations. Nakamura's suggestion (that an additional term in the anomalous heat capacity proportional to the ortho concentration is needed to explain the data) seems to be supported by the analysis, although additional data would be desirable.
Heat of Formation and Entropy of the Trimer of Boron Oxyfluoride
Authors: Farber M.
Published: January 2005

The equilibrium, B2O3(c, 1) + BF3(g) = (BOF)3(g), was studied in the temperature range of 330–1000°K by means of transpiration. The heat of reaction employing crystalline B2O3 was found to be 7.6 kcal/mole; while the liquid B2O3 yielded a ΔHr of 2.4 kcal/mole. These lead to a value of —567.8±0.5 kcal/mole for ΔHf298°K of (BOF)3(g) and a value of 88.7±2 cal/deg/mole for S298 of (BOF)3(g). Partial pressure studies employing mixtures of argon and BF3 indicated that dissociation of the trimer (BOF)3(g) is negligible in the temperature range investigated.
Mass Spectrometry of Ions in Glow Discharges. II. Negative Glow in Rare Gases
Authors: Knewstubb P. F. , Tickner A. W.
Published: January 2005

The ions in the negative glow were examined at pressures of about 0.4 mm and currents of about 0.2 ma. Most of the work was done with argon but some measurements were made with helium and with helium-argon and argon-krypton mixtures. To clarify the role of impurities, some work was done with the addition of 1.25% hydrogen to the argon.

The results confirm that the ions of the principal gas or gases are produced by the impact of ``primary'' electrons. Evidence is obtained that when small amounts of gases having sufficiently low ionization potentials are present, they are ionized by interaction with the metastable atoms of the principal gas.

Ar2+ appears to form in the negative glow mainly by Ar++2Ar→Ar2++Ar,but it is confirmed that in the positive column a process depending mainly on excitation must be dominant.

The formation of ArH+ from impurities is thought to occur principally by the reaction of metastable argon atoms with hydrogen atoms, the latter being produced from various sources by electron impact. In the presence of appreciable quantities of hydrogen, the reactionAr++H2→ArH++Happears to contribute but is only important at the cathode edge of the negative glow.

The extremely persistent formation of H3O+ from traces of water suggests that long-lived excited states of water may exist, and be responsible for this effect.
Relations among Vibrational Frequencies of Isotopically Substituted Molecules and the Determination of Force Constants
Authors: Heicklen Julian
Published: January 2005

A simple derivation is given for the product, sum, and complete isotope rules. Additional sum rules and their implications are presented. In particular, it is shown that if equivalent atoms of a molecule are isotopically substituted, then one relationship (the product rule) exists between two isotopic species; two more relationships (the first-order sum rules) exist among three isotopic species; two more relationships exist among four isotopic species; and for five or more isotopic species all frequencies are related. If the isotopic substitutions retain the full symmetry of the molecule, the aforementioned relationships exist for each symmetry block. Even if isotopic substitution reduces the symmetry, the number of relationships is not diminished. Furthermore, if equivalent atoms are isotopically substituted, then for the inplane vibrations of planar molecules, all the vibrational frequencies are related among four or more isotopic species; for the out-of-plane vibrations of planar molecules and for linear molecules, all the vibrations are related among three or more isotopic species (the complete isotope rule).

To determine the complete F matrix it is necessary to have frequencies of enough molecules so as to include isotopic substitutions of each of the atoms, but one set of equivalent atoms. If less frequencies are known, then information is obtained which relates to the coupling of the isotopically substituted atoms with the remainder of the molecule.
Emission Spectrum of S2 in the Vacuum Ultraviolet Region
Authors: Tanaka Y. , Ogawa M.
Published: January 2005

Four new systems of emission bands of S2 were observed in the region 1760–2125 A. All of them appeared as transitions of the Σ—Σ type. Three of them have no relation to known states and are explained as due to transitions from three upper states at about 7.5 ev to a single lower state at about 1 ev of energy both measured from the ground state. The fourth system is due to a transition from a Σ state at 7.05 ev to the ground state. The weak bands of the transitions C—X and D—X were also observed and compared with the absorption data.
Calculation of Nuclear Magnetic Shielding in Hydrogen Molecule
Authors: Ghosh S. K. , Sinha S. K.
Published: January 2005

The variation method for the calculation of nuclear magnetic shielding as described by Das and Bersohn [Phys. Rev. 104, 849 (1956)] has been shown to be justified on the basis of Rebane's [Soviet Phys.-JETP 11, 694 (1960)] more general considerations. This variation method has been employed to recalculate the proton magnetic shielding in the hydrogen molecule. The vector potential for the externally applied uniform magnetic field H is taken in the following form: Axx≡(0,0,yH);  Ayy≡(0,0,−xH);  and Azz≡(0,xH,0),where, for example, Axx stands for the vector potential when H and μ (the proton magnetic moment) are both in the x direction. The three quantities in the bracket are the three Cartesian components of the vector A. It has been found that with this vector potential, a considerable portion of Ramsey's second-order paramagnetic part can be calculated without considering the excited electronic states of the molecule.
Magnetic Susceptibility of the Cubic Sodium Tungsten Bronzes
Authors: Greiner John D. , Shanks Howard R. , Wallace Duane C.
Published: January 2005

The sodium tungsten bronzes (NaxWO3) in the cubic range 0.45<x<1.0 were found to have mass susceptibilities from 0.007×10—6 for x=0.49 to 0.053×10—6 for x=0.85. This feeble paramagnetism was found to be temperature independent from 70° to 300°K for three representative samples with x=0.49, 0.76, and 0.85. The susceptibility of WO3 was determined to be —0.060×10—6 emu/g and is also temperature independent. Satisfactory agreement between calculated and observed susceptibilities was obtained with a model which assumes that the bronzes consist of a dispersion of sodium ions in a WO3 lattice. The molar susceptibility, then, can be calculated from the equation χM=χ(WO3)+xχ(Na+)+χe. The term χe for the Pauli paramagnetism was obtained for two cases: (a) for nearly free electrons (m*=1.6m), and (b) for the density of states taken from the literature data on the low temperature heat capacity of the bronzes. Best quantitative agreement was obtained between the calculated and the observed susceptibilities for case b and indicates a more rapid increase in the density of states than simply E½.
Photolysis of Mixtures of Cyclobutane and Acetone-d6. Reactions of the Cyclobutyl Radical
Authors: Gordon Alvin S. , Smith S. Ruven , Drew Charles M.
Published: January 2005

The activation energy for abstraction of hydrogen from cyclobutane by a methyl radical is 10.3±0.15 kcal/mole, with a pre-exponential factor relative to methyl radical abstracting D from acetone-d6 of 1.8. At temperatures of less than 200°, the cyclobutyl radicals disappear almost exclusively by combination with methyl radicals to form methyl cyclobutane. At higher temperatures the cyclobutyl radical (a) opens to form the ĊH2CH2CH=CH2 radical with an Eact of 18.1±0.8 kcal/mole, and (b) splits out a molecule of hydrogen. The latter reaction is considerably slower than the former.

The ĊH2CH2CH=CH2 radical is unusually stable, and does not decompose appreciably even at 325°C. At 425°, the highest temperature which could be reliably studied in this system, the product analysis indicates that the radical decomposes slowly to ethylene and a vinyl radical. By contrast, n-butyl radicals and s-butyl radicals readily decompose at 250°C in a similar reaction media. The main reaction of the ĊH2CH2CH=CH2 radical is the abstraction of H (or D) from the parent mixture. It also combines with a methyl radical to form pentene-1. Evidence is presented to show that the ĊH2CH2CH=CH2 radical isomerizes at temperatures of 350° and above to the resonance stabilized CH3ĊHĊHĊH2 radical, with an energy of activation of 20.0±0.7 kcal/mole.
Entropy and Related Thermodynamic Properties of Propionitrile
Authors: Weber Lloyd A. , Kilpatrick John E.
Published: January 2005

The heat capacity and the heats and temperatures of the transitions of propionitrile have been determined experimentally. One solid transition occurred at 176.964±0.005°K and the melting point at 180.37±0.03°K. The entropy of the ideal gas at 25°C and 1 atm is 68.75±0.15 cal/deg mole.
Infrared Absorption of Some Hexagonal Rare-Earth Chlorides
Authors: Varsanyi F. , Dieke G. H.
Published: January 2005

The polarized absorption spectra of anhydrous SmCl3, DyCl3, HoCl3, and ErCl3 diluted with LaCl3 were obtained at 2°K with high resolution between 3000 and 10 000 cm—1. Approximate values for the f values of the transitions lie between 10—9 and 10—6. The selection and polarization rules indicate induced electric dipole transitions except for the transitions between the two lowest components of the ground multiplet which are partly due to magnetic-dipole transitions. Weak infrared fluorescence was observed for DyCl3. The results from the infrared measurements confirm and supplement data on the same energy levels obtained from fluorescence.
Theory of Thermal Diffusion in Dilute Alloys
Authors: Howard R. E. , Manning J. R.
Published: January 2005

A kinetic analysis is made of the thermal diffusion of a dilute impurity in an fcc metal. Expressions are derived for the impurity current, the steady-state Soret gradient, and the mean-atom displacement. It is shown how the ``heats of transport'' appearing in these expressions can be studied experimentally. An extension of the analysis to cases of nonthermal type gradients, in particular a chemical concentration gradient, is briefly considered.
Active Nitrogen at High Pressure
Authors: Noxon J. F.
Published: January 2005

A pure nitrogen afterglow has been studied spectroscopically at pressures up to 1 atm and up to several seconds after the discharge. The first positive bands of nitrogen continue to show an unchanged preferential enhancement of bands with v′=11 at high pressure, but their decay with time, measured photoelectrically, indicates that at high pressure N(4S) atoms must be removed by a more rapid process than recombination in triple collisions; it is suggested that this may be a two-body reaction with an oxide of nitrogen. Forbidden radiation from O, N, and N2 predominates over the first positive bands at high pressure, and a high degree of immunity toward deactivating collisions is shown to be required for the metastable states N(2P), O(1S), and N2(A 3Σu+). The absolute intensity and decay of the forbidden radiation indicates that O(1S) must be created in the afterglow while N(2P), and to some extent N2(A 3Σu+), survive from the discharge. The observations favor a long radiative lifetime near 1 sec for N2(A 3Σu+).
Momentum Transfer to an Atom in a Molecule: Internal Excitation and Bond Dissociation
Authors: Hsiung Chi-hua , Gordus Adon A.
Published: January 2005

An atom will dissociate from a compound if the atom receives a recoil momentum greater than some average value Q0. Considering a polyatomic molecule as composed of point-mass atoms, there is derived an equation which relates Q0 to the bond energy, bond angles and distances, and masses of the atoms in the molecule. The minimum net recoil energy required for bond rupture, the kinetic energy of the recoiling radicals, and the internal energy of the radical originally bonded to the activated atom are calculated for a series of simple alkyl halides.
Failure to Bond Rupture and Nuclear Recoil Following (n, γ) Activation
Authors: Gordus Adon A. , Hsiung Chi-hua
Published: January 2005

Following the absorption of a thermal neutron by 127I or 79Br, the neutron-binding energy is frequently released in the form of a gamma-ray cascade. As a result of partial cancellation of gamma-ray momenta, a small fraction of the activated halogens will not receive sufficient recoil momentum to rupture from their parent compound. The gas-phase failures to bond rupture following 127I(n, γ) 128I, and 79Br(n, γ) 80Br activation were found experimentally to be: CH3I—1.09, CD3I—0.68, CF3I—0.12, CH2I2—0.068, C2H5I—0.082, n-C3H7I—0.66, i-C3H7I—0.30, CH3Br—0.25, CD3Br—0.20, CH2Br2—0.12, CF3Br—0.11, CF2Br2—0.093, CHClBr2—0.087, CCl3Br—0.066, CHBr3—0.05, CBr4—0.03, C2H5Br—0.33, and 1,1-C2H4Br2—0.17%. These data are correlated with the calculated recoil energies required for bond rupture (preceding article). Using as a basis the distribution of net gamma-ray energies calculated by the random-walk method for the 35Cl(n, γ) 36Cl process, the kinetic-energy distributions of the dissociated 128I or 80Br are approximated. These data suggest that the extent of hot-atom reaction of 128I or 80Br with CH4 should not depend upon the parent molecule from which the activated halogen dissociates.
Spectrum of C3
Authors: Brewer Leo , Engelke John L.
Published: January 2005

The enthalpy of sublimation of C3 as determined by a second law method using both emission and absorption measurements agrees with total vapor pressure and mass spectrometer measurements. The enthalpy agreement and integrated absorption coefficient measurements demonstrate that the so-called continuum of C3 is a pseudocontinuum and involves the same bound states as the discrete Swings bands of C3(A1Πu↔X1Σg+). ΔH0°=188±5 kcal/mole for the sublimation of C3 yields an oscillator strength for the 4050 A bands of C3 of 0.13 within a factor of 2.
Deuteron Magnetic Resonance Study of Several Deuterated Ammonium Salts
Authors: Chiba Takehiko
Published: January 2005

Deuteron magnetic resonance spectra were observed in ND4Cl, ND4Br, ND4ClO4, ND4BF4, ND4IO3, and (ND4)2SO4 in their powder form. Absorption patterns characteristic of the rapid reorientation of ND4+ ions were obtained. For the first four compounds, the absorption line consists of a sharp single line; for the remaining two it has structure which is due to small quadrupole coupling. For (ND4)2SO4, the angular dependence of the resonance pattern was measured with a single crystal specimen. The following values of the quadrupole coupling constant and asymmetry parameter were obtained: ND4IO3:  |eqQ|/h=3.9±0.3 kc,η=1.0−0.8,(ND4)2SO4:  |eqQ|/h=4.17±0.05 kc,η=1.0−0.95,and |eqQ|/h=2.00±0.05 kc,  η=1.0−0.8.The results of the experiment were discussed in relation to the crystal structure, crystalline field effect, and the deformation of ND4+ ion in the crystal. It was concluded that the observed quadrupole coupling for ammonium sulfate is mainly due to a direct effect of the distortion of the ammonium ion in the crystal rather than to the crystalline field effect. The observed asymmetry parameter for ammonium iodate did not agree with the reported crystal structure.
Electron Spin Resonance of an Irradiated Single Crystal of Deuterated DL-Tartaric Acid
Authors: Rao D. V. G. L. Narasimha , Gordy Walter
Published: January 2005

The electron spin resonance spectra of an irradiated single crystal of DL-tartaric acid grown from water was found to be complex, but the spectra of a deuterated single crystal could be analyzed and the nature of the free radical ascertained. Measurements were made at 9 and at 23 kMc/sec. For some orientations of the crystal in the external magnetic field an unresolved doublet was observed with weak satellite lines separated by 5 gauss at 9 kMc/sec and by 13 gauss at 23 kMc/sec. These satellite lines evidently arise from second-order transitions. From the analysis we suggest that the free radical is probably[Complex chemical formula]with the unpaired spin on a carbon atom. The principal values of g are 2.0025, 2.0026, and 2.0047. The principal elements of the nuclear coupling of the CH protons are ∓0.2, ±1.1, and ±6.5 gauss.
Electron Spin Resonance Absorption and Other Properties of Some Solid Hydrocarbon-Quinone Complexes
Authors: Eastman John W. , Androes Gaylord M. , Calvin Melvin
Published: January 2005

Crystalline solids have been prepared from aromatic hydrocarbons and tetrahalogenated benzoquinones. The solids contain one molecule of hydrocarbon for every molecule of quinone. The infrared and optical spectra of the solids, as well as their chemical properties, indicate that the components are bound by electronic donor-acceptor interactions which are weak compared to the intramolecular forces.

Electron spin resonance absorption at 9500 Mc/sec was observed in nearly all the hydrocarbon-quinone solids prepared. However, perylene-quinone solids have been prepared which contain less than 1015 unpaired electron spins per gram. That is, they are practically diamagnetic. When unpaired electrons are present they are located at imperfections in the solid. Imperfections containing unpaired electron spins can be introduced thermally into the complexes. More than 1018 unpaired electrons per gram can be produced by heating perylene-ortho-quinone solids.

The temperature dependences, g values, linewidths and spin-lattice relaxation times of the electron spin resonance absorption by the imperfection in some perylene-quinone solids have been investigated. The structure of the imperfection and the mechanism by which it is produced have been discussed.
Molecular Structure of Ethyl Chloride
Authors: Schwendeman R. H. , Jacobs G. D.
Published: January 2005

The microwave spectra of C13H3CH2Cl35, CH3C13H2Cl35, CH3CD2Cl35, and CH2DCH2Cl35 have been examined and rotational constants assigned. Both a-type and b-type spectra have been observed. From these spectra and those previously reported for CH3CH2Cl35, CH3CH2Cl37, and CH2DCH2Cl35 a complete structure has been obtained by means of the substitution method. The bond distances and bond angles obtained are as follows: CC = 1.520 A, CCl = 1.788 A, CH (methyl) = 1.091 A, CH (methylene) = 1.089 A, CCCl = 111°2′, HCH (methyl) = 108°30′, HCH (methylene) = 109°12′, CCH (methylene) = 111°36′. The quadrupole coupling parameters and barrier to internal rotation have been re-evaluated in terms of the above structure. The quadrupole coupling parameters are χbond = —68.80 Mc and ηbond = 0.035, if the angle between the a axis and the CCl bond is determined from the structure; or χbond = —71.24 Mc, if a cylindrical charge distribution is assumed near the chlorine nucleus. The barrier to internal rotation is 3685 cal/mole.
Deactivation of Hg (63P1) by CO and N2
Authors: Scheer Milton D. , Fine Joseph
Published: January 2005

Atoms of Hg(63P0) produced by collisions between Hg(63P1) and either N2 or CO were detected by measuring the electrons ejected from a silver surface. From the pressure dependence of this effect, it was shown that the quenching of Hg(63P1) to Hg(63P0) by collision with CO occurs at about the same rate as with N2. Since CO is 20 times more efficient than N2 in the quenching of 2537 A fluorescence, the process [Hg(63P1)+CO→Hg(61S0)+CO*]must be much faster than the corresponding reaction with N2. A possible explanation of this effect is the intermediate formation of HgCO*, which dissociates to Hg(61S0) and vibrationally excited CO(v=20). This could account for the fact that H2CO and (HCO)2 are formed in the Hg photosensitized reaction of H2 and CO and not in the electric discharge experiments of H atoms reacting with ground state CO.
Method for Determining Conformations of Polymer Molecules in Crystalline State from Fiber Identity Distances
Authors: Nagai Kazuo , Kobayashi Masamichi
Published: January 2005

A mathematical method is presented for determining helical conformations, or more precisely, positions of atoms relative to the helical axis and internal rotational angles about skeletal bonds, of a polymer molecule in crystalline state, straightforwardly from bond lengths and bond angles of the chain skeleton, and the translational distance along the helical axis and the rotational angle about the axis per one repeating unit. The treatment is confined to one-, two-, and three-atom helices, i.e., those whose stereochemical and conformational repeating units are composed of one, two, and three consecutive skeletal atoms, respectively. A nonhelical conformation also is included as a special helix. The method is illustrated by the two examples, poly-p-fluorostyrene and polypeptides, for which it was originally devised.
Enhancement of Eu3+ Emission by Tb3+
Authors: Van Uitert L. G. , Soden R. R.
Published: January 2005

The intensities of emission of Eu3+ in the alkali metal ion rare-earth tungstates can be greatly enhanced by incorporating Tb3+ as part of the host lattice. The degree of enhancement appears to be proportional to the terbium concentration. The gain in the intensity of emission of Eu3+ that is attributable to interaction with Tb3+ is related to the lattice cohesive force operating on the europium ion.
On the Splitting of Entropy Production Terms into Flux and Force Factors
Authors: Van Rysselberghe Pierre
Published: January 2005

It is suggested that irreversible processes obeying phenomenological laws such as Fick's diffusion law, Fourier's heat conductivity law, etc., be treated, in the thermodynamics of irreversible processes, with phenomenological coefficients coinciding with those appearing in these laws (Fick's diffusion coefficient, Fourier's heat conductivity coefficient, etc.) and with accordingly modified mutual influence coefficients, even though the corresponding fluxes and forces are then different from the actual flows in space (diffusion flow, heat flow, etc.) and their conjugate forces.
General Reciprocity Relation between the Rates and Affinities of Simultaneous Chemical Reactions
Authors: Van Rysselberghe Pierre
Published: January 2005

A derivation of the general reciprocity relation ∂v1/∂A2=∂v2/∂A1 between the rates and affinities of simultaneous chemical reactions is presented. The Onsager symmetry relation L12=L21 between mutual influence coefficients is obtained in the limiting case of the linear relations between rates and affinities valid in the neighborhood of equilibrium.
Analysis of Paramagnetic Resonance Properties of Pure and Bleached F Centers in Potassium Chloride
Authors: Noble Gordon A. , Markham Jordan J.
Published: January 2005

The electron paramagnetic resonance of color centers in additively colored KCl crystals is measured carefully to observe the effects of optical bleaching at room temperature. Earlier measurements on the F center are confirmed and the susceptibility is measured at 78° and 300°K over five decades of power, including the very low power region. The width and the saturation properties of the individual multiplets are studied in detail and the technique of making EPR measurements on inhomogeneously broadened lines is discussed. A calculation is presented which shows that a slight departure from a Lorentzian multiplet shape can account for the saturation data.

The bleached crystals show a resonance which has a width of 35 gauss and a different rate of saturation than the F center. This resonance is associated with the B band which appears in the optical absorption.
Interaction of Helium, Neon, Argon, and Krypton with a Clean Platinum Surface
Authors: Chon H. , Fisher R. A. , McCammon R. D. , Aston J. G.
Published: January 2005

The heats of adsorption of helium, neon, argon, and krypton have been studied on a clean platinum black of high area, prepared using the technique of a thermally indicated titration.

These measured heats are compared with the theoretically calculated attractive part of interaction energy between a nonpolar gas and a metal surface.

The Margenau and Pollard formulas best represents the measured values. Considering the uncertainty involved due to lateral interaction and the neglected repulsive part of the potential function it is reasonable to say that all of the theories are inagreement with the measured values to the degree of their approximation.
Quantum Mechanical Study of the Hydrogen Bimolecular Exchange Reaction
Authors: Ruffa A. R. , Griffing Virginia
Published: January 2005

A theoretical calculation of the potential-energy curves of several linear four-atom hydrogen complexes has been made in order to study the interaction governing the kinetics of the bimolecular exchange reaction. In particular, an attempt was made to determine for what distance of approach the two diatomic molecules make a transition into the four-atom complex. Hence, the linear H4 complex H—r—H—R—H—r—H was chosen for study as function of r and R. The partial potential energy surface constructed in this manner indicates that two hydrogen molecules approaching on a line experience an increase in interatomic separation with the inner two atoms forming a hydrogen molecule at small separations while the outer two atoms are repelled outward from the center of the system. The minimum occurs for r=R=1.8 and gives an activation energy of 65 kcal for the bimolecular exchange reaction, if one assumes a linear transition state.

An additional calculation was performed on a linear chain of six hydrogen atoms with interatomic separation of two atomic units in order to get additional information regarding the relative stability of the linear hydrogen chain in comparison with other possible configurations. Computation of the total energies in the LCAO MO SCF approximation with 1s functions indicates that the energies of the chains of four or six hydrogen atoms generally lie between the energies of the separated hydrogen molecules and the separated hydrogen atoms.
Excitation of Molecular Vibration by Slow Electron Impact
Authors: Chen J. C. Y. , Magee J. L.
Published: January 2005

A mechanism for excitation of molecular vibration by slow electron impact involving negative-ion states as intermediates is proposed and discussed. It is believed that this mechanism is the most important energy loss mechanism for slow electrons for energy regions in which it occurs. Calculation of the vibrational excitation cross section using the proposed mechanism has been carried out for hydrogen molecules and the result is compared with the experimental observations. The estimated cross section is in the order of 1 A2.
Dissociation Pressure of Uranium Dicarbide
Authors: Leitnaker James M. , Witteman Willard G.
Published: January 2005

Vapor transport of uranium from UC1.86 in a graphite crucible has been measured from 1930° to 2365°K by the Knudsen technique. In order to treat the data, unusual assumptions have been made concerning the thermal properties of carbides which hydrolyze to yield hydrocarbons. The gaseous uranium species is assumed to be monatomic. With the aid of these assumptions, the data have been treated by the third-law method as well as by the second-law method. Agreement between the two is considered good, and the ΔH298° obtained for the process UC1.86(s)=U(g)+1.86 C (graphite)is 140.15±1.82 kcal/mole. Reasonable estimations for reaction entropies within the system lead to an upper limit of 0.5 kcal/mole for ΔH298° for the reactionUC(s)+0.86 C (graphite)=UC1.86(s),and hence a value of 119.8±2.8 kcal/mole is obtained as an upper limit for ΔH298° of vaporization of uranium.
Studies of the Vapors of the System Au–Cr and Au–Pd by Mass Spectrometry
Authors: Ackerman Marcel , Stafford Fred E. , Verhaegen Georges
Published: January 2005

The molecules AuCr and AuPd have been identified. From data for the reaction Au2+X=AuX+Au, and D0°(Au2)=51.5 kcal/mole: D0∘(AuCr)=50.4±3.5 kcal/mole,D0∘(AuPd)=33.3±5 kcal/mole.
Dielectric Relaxation of Water Adsorbed on γ-Alumina
Authors: Dransfeld Klaus , Frisch H. L. , Wood E. A.
Published: January 2005

For several adsorbed vapors it is well known that they remain apparently ``liquid'' down to temperatures considerably below the melting point of the bulk liquid, and that on further cooling they show only a very gradual ``freezing'' over a wide temperature range. In order to shed some light on the nature of this solidification process we have measured the dielectric relaxation time of water adsorbed on γ-alumina between room temperature and 180°K. The water content was sufficient for capillary condensation to occur. The temperature dependence of the measured relaxation rate strongly resembles that of supercooled liquids, suggesting that the solidification of capillary water may be considered as a transition from a supercooled liquid into a ``glassy'' solid state.
Dielectric Behavior of Water Adsorbed on Alumina
Authors: Baldwin Mart G. , Morrow J. C.
Published: January 2005

The dielectric behavior of water adsorbed on gamma alumina has been investigated by measuring dielectric constant and loss tangent as functions of temperature (0–86°C), amount adsorbed (0–220 mg H2O/g Al2O3), and frequency (50 cps—100 kc). The results are those expected for a multilayer adsorption system in which the monolayer is very strongly bound and in which molecules in layers above the first are relatively free to orient under the influence of applied field. The temperature coefficient of the vapor pressure of the system for fixed amount adsorbed has been measured to provide an enthalpy of adsorption which has been compared with enthalpy of orientation obtained from the dielectric measurements.
Heat Conductivity of Polyatomic and Polar Gases
Authors: Mason E. A. , Monchick L.
Published: January 2005

The formal kinetic theory of Wang Chang and Uhlenbeck and of Taxman has been used to derive explicit expressions for the heat conductivity of polyatomic and polar gases. By systematic inclusion of terms involving inelastic collisions the usual modified Eucken expression is derived as a first approximation, and as a second approximation an expression involving the relaxation times for various internal degrees of freedom (as well as the viscosity, diffusion coefficients, and heat capacity). For polar gases a second effect is often important in that a resonant exchange of rotational energy is possible.

The comparison of experimental results with those calculated using empirical values of relaxation times is generally satisfactory, and most of the previously noted anomalies in the ratio f=λM/ηCv are accounted for quantitatively.
Absorption and Dispersion of Sound in Critical Mixtures
Authors: Fixman Marshall
Published: January 2005

The entropy previously associated with the long wavelength spectrum of composition fluctuations in the critical mixing region is studied under the supposition that the temperature varies harmonically with time. Relaxation effects in the response of the long range part of the radial distribution function to the temperature variation produce a complex heat capacity. The consequent sound absorption rises to a maximum at the critical point, in good quantitative agreement with experiment. The equation of motion for the radial distributions function is the modified diffusion equation previously used in a theory of the anomalous viscosity rise in the critical mixing region.
Preparation of Semiconducting Diamonds
Authors: Wentorf R. H. , Bovenkerk H. P.
Published: January 2005

P-type semiconducting diamonds can be formed at high pressures and temperatures out of mixtures of graphite and catalyst metal (Ni, Fe, etc.) to which small amounts of B, Be, or Al have been added. The crystals may have resistivities of as low as 103 ohm-cm with activation energies for conduction ranging between 0.1 and 0.35 ev. Semiconducting crystals may also be prepared by allowing B or Be to diffuse into diamond crystals at high pressures and temperatures. The crystals prepared with high concentrations of boron are blue. No n-type crystals have been prepared so far.
On the Thermodynamics of Solutions. VII. Critical Properties of Mixtures
Authors: Redlich O. , Kister A. T.
Published: January 2005

The applicability of equations of state has been greatly widened by automatic computation. Algebraic relations, however, particularly strict thermodynamic relations, are apt to simplify the calculations and therefore to extend the applications much further.

Explicit general relations between temperature, pressure and composition at the critical line of a binary mixture would be useful and also theoretically interesting. Although the problem is easily formulated, it appears that a general solution cannot be found. But a partial solution can be derived: The derivatives of the variables of state along the critical line in the limits of the critical points of the pure components can be expressed by partial derivatives in these points.

The volume of a mixture increases on condensation in the range of retrograde condensation. This result may have been suspected on the basis of the principle of Braun and Le Chatelier.
Collision-Induced Microwave Absorption in Compressed Gases. I. Dependence on Density, Temperature, and Frequency in CO2
Authors: Maryott A. A. , Birnbaum G.
Published: January 2005

Measurements of the dielectric loss by a resonant cavity technique at 9 and 24 kMc/sec are reported for CO2 for densities up to 100 amagat and 25°C. Some additional data are reported at elevated temperatures. The loss, which increases in proportion to the frequency and very nearly as the square of the density, is attributed to transient dipoles induced by the molecular electric quadrupole fields during molecular collisions. A theoretical analysis including the line shape is made to relate the loss to the pertinent molecular parameters and to permit an intercomparison with precise data available on the second dielectric virial coefficient. It is concluded that the microwave loss in quadrupolar gases may provide a sensitive method of getting information on the molecular quadrupole moments.
Computer Assignment Technique for Analysis of High-Resolution NMR Spectra
Authors: Whitman Donald R.
Published: January 2005

A computer assignment technique for calculating chemical shifts and spin coupling constants from experimental high-resolution proton magnetic resonance spectra is described. The observed spectral lines are assigned to transitions within the energy-level diagram in a manner consistent with equal-spacing and intensity-sum rules. Experimental eigenvalues are calculated and introduced into equations derived from the spin Hamiltonian secular determinant in analytical form and in the diagonal experimentally observed form. These equations are implicit in the chemical shifts and spin coupling constants and in general must be solved by numerical methods although in some cases explicit solutions are found. The technique is applied to the 60 Mc spectrum of o-dichlorobenzene to obtain the results δ=15.23 cps, J12=8.17 cps, J23=7.44 cps, J13=1.61 cps, and J14=0.36 cps.
Positron Annihilation in Some Organic Compounds
Authors: Kerr D. P. , Hogg B. G.
Published: January 2005

The intensity I2 and the mean life τ2 of the long-lived component in positron decay have been measured in a number of organic halides using a fast time to pulse-height converter. In general, compounds containing a chlorine atom showed an I2 of about 16%, those containing bromine an I2 of about 10%, and those containing iodine an I2 of about 4%. The τ2 values for a number of organic compounds containing chlorine varied from 1 to 2 n sec.
Measured Transition Probability for the First-Positive Band System of Nitrogen
Authors: Wurster Walter H.
Published: January 2005

The electronic transition probability for the nitrogen first-positive system has been obtained from absolute spectral-intensity measurements of the infrared radiation from shock-heated nitrogen. A 12-channel spectrometer was used, whose resolution was sufficient to separate the vibrational band sequences. The temperature dependence of the spectrum was shown to agree with that determined for nitrogen in thermodynamic equilibrium. An electronic transition moment | Re |2 equal to 0.096 a.u. and independent of internuclear separation gave the best fit to the data. The measured intensities are shown to be lower by a factor of 5 than those reported for measurements in shock-heated air, and the corresponding f number, evaluated at 9512 cm—1 (v′=v″=0), was found to be (2.8±0.7)×10—3. A second component of radiation was detected, and shown to be attributable to either the CN red or N2+ Meinel band systems.
Molecular Orbital Calculations of Excited States of H2
Authors: Zung Joseph T. , Duncan A. B. F.
Published: January 2005

Energies of the lowest 1Σg+ and 3Σg+ states of H2 are computed with relatively simple molecular orbital (MO) functions. The MO functions are constructed from 1s, 2s, and 2pz atomic functions, with variable orbital parameters. The MO's are kept orthonormal during extensive variation of the orbital parameters and the internuclear distance. Minimum energies of antisymmetrized products of the MO functions and corresponding best values of the orbital parameters are obtained. The final energies are somewhat inferior to values obtained by Kolos and Roothaan for the singlet state and James and Cooledge for the triplet state, but are better than values obtained with one-center functions. The final functions satisfy the virial theorem at R close to the experimental equilibrium value.
Dielectric Saturation and Hydrogen Bonding
Authors: Piekara A.
Published: January 2005

A new type of effect of dielectric saturation, as found by J. Mal/ecki in alcohols and their solutions in nondipolar solvents, consists in the fact that an external electric field raises the dielectric permittivity of solutions of low concentration and lowers that of strong ones. The rise in permittivity (positive saturation effect) is due to the presence of dimers, whereas its decrease (negative saturation effect)—to multimers, chiefly tetramers. The latter effect is essentially one of orientation of the multimers in the electric field. In addition, the proton shift due to the electric field introduces a small variation in the electric moment of the multimers, but raises that of the dimers very considerably, leading to the positive saturation effect in alcohol solutions of low concentration.