bluuebunny/crossref_metadata_2025 huggingface dataset:
On Diagonalizing Phenomenological Matrices
Authors: Manes Milton
Published: January 2005

A homogeneous many-reaction system close to equilibrium is considered, in which it is postulated that the stoichiometric equations for the real reactions are linearly independent and that the rate of each reaction is proportional to its affinity and independent of all other affinities. It is shown that the symmetric (but non-diagonal) matrix that relates the rates to the affinities of a linearly independent but fictitious set of reactions can be made to display the identity of the real reactions if one can independently modify the real equilibration velocities. Formal diagonalization of a nondiagonal phenomenological matrix is shown to be an improper procedure for finding the real reactions; moreover, the set of equations found by this method loses its diagonality when the real equilibration velocities are modified. By contrast, the matrix relating the rates of the real reactions to their affinities retains its diagonality throughout all modifications of the equilibration velocities. This stronger diagonality condition is suggested as a criterion for real independent reactions. The results should be applicable to nonequilibrium thermodynamics.
Calculation of Exact Eigenfunctions of Spin and Orbital Angular Momentum Using the Projection Operator Method
Authors: Rotenberg A.
Published: January 2005

Using the projection operator technique a code has been written for the IBM-7090 to generate electronic wavefunctions which are eigenfunctions of both spin and orbital angular momentum. All the functions which arise in the L—S coupling of any allowed system of electrons in a single s, p, d, or f shell can be computed as well as some functions for a few electrons in the g shell. Also, functions arising in the coupling of electrons in different shells are obtained, and these eigenfunctions are of particular interest in configuration interaction studies of atomic structure. A few representative eigenfunctions are listed. In addition an auxiliary code was written to give the terms arising in L—S coupling.
Centrifugal Distortion Corrections to Calculated Thermodynamic Functions
Authors: McDowell Robin S.
Published: January 2005

Partition functions for nonrigid rotators are obtained for the linear, spherical-top, and symmetric-top cases. From these are derived expressions giving the corrections to the thermodynamic functions due to centrifugal distortion as functions of the rotational distortion constants D. Numerical examples are given for HCN, methane, and ammonia.
Nuclear Magnetic Relaxation and Diffusion in Liquid CH4, CF4, and Mixtures of CH4 and CF4 with Argon
Authors: Rugheimer John H. , Hubbard Paul S.
Published: January 2005

The longitudinal nuclear magnetic relaxation times and diffusion coefficients of CH4, CF4, and mixtures of CH4 and CF4 with argon have been measured at temperatures between the freezing points and the boiling points of the liquids by use of spin-echo techniques. Misch metal was used as a getter to remove oxygen from the samples. The relative numbers of spins per unit volume have also been measured. The measured values of the relaxation time T1 are compared with values calculated on the assumption that the relaxation is due to spin—rotational interactions and to intra and intermolecular dipole—dipole interactions. The calculated and measured values of (1/T1) differ by a factor of as much as 4 for pure liquid CH4 and as much as 12 for the argon—CH4 mixture. The calculated and measured values of (1/T1) for pure liquid CF4 and for the argon—CF4 mixture agree quite well if reasonable values of the spin—rotational interaction constants are assumed. The calculated contribution of the spin—rotational interactions to (1/T1) is negligible for liquid CH4, and is comparable to the contributions of the dipole—dipole interactions for liquid CF4.
Calculations of Higher-Order Spectroscopic Parameters Using Empirical Potential Functions
Authors: Stutman Joel M. , Lippincott Ellis R. , Steele Derek
Published: January 2005

Empirical internuclear potential functions have been used to predict higher-order spectroscopic parameters for ground and excited states of a representative sample of diatomic molecules. The parameters, viz., second-order anharmonicities, ωeye, rotational—vibrational coupling constants, γe, and the first-order vibrational corrections to the second-order rotational constants, βe, have been computed through the Dunham relations for the Hulburt—Hirschfelder, Varshni III, and Lippincott empirical internuclear potential functions. A table of Dunham-corrected equilibrium vibrational frequencies and equilibrium internuclear distances is given. The predicted values for the higher-order spectroscopic parameters are compared with experimental values as found in the literature. Deviations of predicted from experimental values are discussed from different approaches. The empirical functions discussed should be useful in obtaining estimates of ωeye, γe, and βe when such values are not available because of limited experimental data.
Physical and Chemical Effects at the Anthracene—Electrolyte Interface due to Photoelectrolysis
Authors: Jarnagin R. C. , Gilliland J. , Kim J. S. , Silver M.
Published: January 2005

Processes at the dark hole discharge surface of photoconducting anthracene in contact with aqueous inert electrolyte have been examined. O2 was shown to be consumed and anthraquinone formed due to electrolysis. Directional etching of the (001) discharge surface was shown to occur and related to (010) slip planes which were probably developed during growth from the melt. Significance of defects to current carrier trapping was indicated and possible mechanism of carrier discharge was discussed.
Microwave Spectrum and Structure of Pentafluorosulfur Bromide
Authors: Neuvar Erwin W. , Jache Albert W.
Published: January 2005

Rotational spectra of pentafluorosulfur bromide observed with a video microwave spectrometer in the region 51–54 kMc/sec were fitted to the following molecular constants and structural parameters: S32F5Br79–B0 = 1172.153±0.002 Mc/sec, DJ = 0.0672±0.0400 kc/sec, DJK = 0, eQq(Br79) = 800±5 Mc/sec; S32F5Br81–B0 = 1159.875±0.002 Mc/sec, DJ = 0.1612±0.0400 kc/sec, DJK = 0, eQq(Br81) = 705±5 Mc/sec; θF–S–F(axial) = 88° (assumed), dS–Br = 2.1902±0.0065 Å, dS–F = 1.5970±0.0025 Å. The long S–Br bond distance is attributed to the steric interaction between the bromine atom and the F4 group. The value of the quadrupole coupling constant for the bromine nucleus suggests that the S–Br bond is predominantly covalent with some ionic character from resonance forms involving a positive charge on the bromine atom.
Dielectric Relaxation of Some Aromatic Molecules Containing Methoxy Groups
Authors: Vaughan W. E. , Roeder S. B. W. , Provder T.
Published: January 2005

The dielectric constants and losses of a series of aromatic molecules containing methoxy groups have been measured at 2.2-mm wavelength in the liquid state at various temperatures between 20° and 80°. The results, together with existing lower-frequency data, are used for an expansion of the complex reduced dielectric constant in a series of terms of the Debye type. The effect of molecular and liquid structure, and temperature on the parameters obtained is discussed.
Infrared Spectroscopic Evidence for the Species HNC
Authors: Milligan Dolphus E. , Jacox Marilyn E.
Published: January 2005

Prolonged photolysis of CH3N3 in an Ar matrix at 4°K produces HNC by the photolytic decomposition of the initially produced CH2=NH. Infrared observations on various isotopically substituted species confirm this identification and indicate that HNC is linear. The force constants and thermodynamic properties of HNC are presented.
Comparison of the Hartree—Fock Orbital with the First Natural Spin Orbital for Two-Electron Systems
Authors: Nazaroff George V. , Hirschfelder Joseph O.
Published: January 2005

A demonstration is given that for two-electron systems the Hartree—Fock and first natural spin orbitals are different functions. The method used is perturbation theory for which the zero-order problem is the Hartree—Fock approximation. A perturbation expansion through the second order is obtained for the first natural spin orbital. The two orbitals begin to differ in the second order, and their energies in the fourth order. An equation for the second-order part of the orbital difference function is derived. Estimates of the norms of the orbital difference functions are calculated for the ground states of the helium atom and the hydrogen molecule and are found to be small.
Comparison of Dielectric and Mechanical Relaxation in Associated Liquids
Authors: Litovitz T. A. , McDuffie G. E.
Published: January 2005

A comparison is made of existing dielectric and ultrasonic shear and compressional relaxation data in several associated liquids including glycerol, hexanetriol 1,2,6, butanediol 1,3, 2-methyl pentanediol 2,4, and n-propyl alcohol. The data show that the pressure and temperature dependences of the dielectric time τD and the volume relaxation times τv are very similar indicating a close connection between the two processes. It is proposed here that cooperative effects cause the distribution of mechanical relaxation times in these liquids as well as the non-Arrhenius behavior of the temperature dependence of the shear and volume viscosities. It is further suggested that structural relaxation is a rate-determining step in the dielectric relaxation process and that the origin of the distribution of dielectric times is the distribution of structural relaxation times.
Gas-Phase Radiolysis of n-Butane
Authors: Borkowski R. P. , Ausloos P. J.
Published: January 2005

The γ-ray radiolysis of n-C4D10–n-C4H10–I2 mixtures has been investigated in the presence and in the absence of inert gases. Benzene has been added in a few experiments. In the direct and in the inert gas sensitized radiolyses, more than 95% of the propane is formed via the hydride transfer reaction: sec−C3H7++C4H10→C3H8+C4H9+.

Part of the ethane, ethylene, and propylene can be ascribed to hydride transfer reactions involving C2H5+, C2H3+, and C3H5+, respectively. The yield of these fragments relative to that of the C3H7+ increases with the recombination energy of the added inert gas. A few photochemical and radiolytic experiments using CH3CH2CD2CD3 have been carried out in order to elucidate the mechanism of the molecular detachment processes.

It can be calculated from the results that the relative yields of the fragments produced in the direct radiolysis do not exactly agree with those deduced from the mass spectrometric cracking pattern obtained at 70 eV. The discrepancy is largest for the fragments produced at a high appearance potential. The data also indicate that, in the radiolysis, the contribution of neutral excited molecule decomposition may be considerably less important than recently reported by Beck and Niehaus for pressures around 10—5 mm Hg.
Mass Spectra and Appearance Potentials of Diazirine and Diazomethane
Authors: Paulett Grover S. , Ettinger Raymond
Published: January 2005

Appearance potentials have been determined for CH2+, CHN2+, and CH2N2+ in the mass spectra of diazirine (cyclic-CH2N2) and diazomethane. The spectrum of diazomethane previously reported in the literature was found to be in error, and has been reinvestigated. The heats of formation of diazirine and diazomethane are estimated to be 79·3 and 49·3 kcal/mole, respectively, while approximate heats of formation of CH2N2+ and CHN2+ derived from the two isomers suggest the possibility of common cation structures.
Mass Spectrometric Study of Positive-Ion Emission from Iron Oxide Catalysts Containing Alkali Metals
Authors: Tsuchiya Toshikazu
Published: January 2005

Samples of iron oxide catalysts containing small amounts of added alkali-metal oxides were mounted in the ionization chamber of a mass spectrometer equipped with a grid. The evaporation products obtained under various conditions were investigated. Alkali atom emission, the intensity of which decayed rapidly, and alkali ion emission were measured. The ratio of potassium ion emission to sodium ion emission from samples containing the two alkalis decreased markedly with heating time. The magnitude of the experimentally derived apparent work functions for evaporation of the alkali ions from the iron oxide catalysts agreed with those computed for the evaporation of the same ions from pure alkali metals.
Zero-Field Splitting in 3d5 Ions
Authors: Chakravarty A. S.
Published: January 2005

The origin of the zero-field splittings of the orbitally nondegenerate ground states of the transition metal ions (3d3, 3d5, and 3d8 solutes) has been studied on the assumption that these splittings are due to the combined action of an electric field gradient and the spin—spin interaction. A relation between the splitting parameters D and E of the conventional spin Hamiltonian and the field gradients q| | and ηq| |, respectively, has been deduced on the above basis using hydrogenic wavefunctions and d→d, d→g, and d→s excitations. A reasonably good agreement with the splitting has been obtained for Mn2+ in corundum but an apparent disagreement has been found for Fe3+ in Al2O3, considering the known values of the field gradients in these cases. For Cr3+ (d3 solute) and Ni2+ (d8 solute) in corundum, the major sources of splitting seem to be the spin—orbit interaction and the distortion of the ground state wavefunctions due to covalent π bonding and not the spin—spin interaction. The cause of the apparent disagreement for Fe3+ in Al2O3 is discussed. A definite understanding of the cause of the zero-field splittings in the transition metal ions depends on more accurate knowledge of the field gradients acting on these ions in different crystalline environments.
Infrared Spectra in Polarized Light and Vibrational Assignment of the Infrared-Active Modes of Pyrene and Pyrene-d10
Authors: Califano S. , Abbondanza G.
Published: January 2005

The infrared spectra of pyrene and pyrene-d10 in the crystalline state and in solution of various solvents were measured between 4000 and 400 cm-1.

Spectra in polarized light with the electric vector of the incident light vibrating in the ab crystal plane were obtained from both single crystals and oriented polycrystalline samples. Spectra in polarized light with the electric vector in the ac crystal plane were also obtained from oriented films. The comparison of the experimental dichroism with the predictions based on the knowledge of the crystal structure allowed an almost complete assignment of the fundamental modes of vibrations active in the ir spectrum.
X-Ray and Electrical Conductivity Study of the Fluorite Phase in the System ZrO2–CaO
Authors: Tien T. Y. , Subbarao E. C.
Published: January 2005

In the ZrO2–CaO system cubic solid solutions of the fluorite-type structure are formed between 12 and 22 mole % CaO for specimens fired at 2000°C and subsequently quenched from 1400°C. The lattice parameter increased linearly from 5.125 to 5.144 Å with increasing CaO content. Results of x-ray diffraction intensity studies favored the oxygen-ion vacancy model over the cation interstitial model for these solid solutions. As the CaO content was increased from 13 to 20 mole %, the electrical conductivity at 1000°C decreased from 5×10—2 to 6×10—3 Ω—1 cm—1 and the activation energy increased from 1.11 to 1.35 eV. Specimens heated at 1000°C for one week showed extra x-ray diffraction lines. These data coupled with accompanying changes in electrical conductivity are discussed in terms of an order—disorder transition.
Simultaneous Measurement of HI Fundamental and Overtone Lines
Authors: Benesch William
Published: January 2005

Measurements of absorption line intensities in the HI overtone band at 2.3 μ have been undertaken by a method of comparison with lines in the fundamental. The technique employed lends itself particularly well to the obtaining of consistent data from two bands, which is most important for the determination of the coefficients of the dipole-moment function. These considerations led to the selection of the six overtone lines P (2) through R (3) for measurement.

One interesting aspect of the overtone intensities and matrix elements is the similarity of their magnitudes to those of the fundamental. Thus, extrapolating from the measured data to obtain a total overtone band intensity, a value of 0.19±0.02 cm—2 atm—1 at 300°K is deduced. This is more than half the fundamental-band intensity. On the other hand, as contrasted with the fundamental, there is virtually no distortion of the overtone band arising from the interaction of vibration and rotation. Consideration of all the data thus far collected on HI leads to the conclusion that the fundamental matrix elements must be negative and the overtone matrix elements positive. Likewise, it may be inferred that the value of θ2=M2re/M1 is about —5.
Melting Properties of Silver Nitrate to 10 000 Atm
Authors: Owens B. B.
Published: January 2005

The effects of pressure on the volume of fusion and the melting point of silver nitrate have been determined up to 10 000 atm. The extrapolated value for the volume of fusion at zero pressure is 2.58 cc/mole, as compared to the literature value of 0.3 cc/mole. On the basis of the Clausius—Clapeyron equation, a value of 2.54 cc/mole was calculated for the volume of fusion from the limiting slope of the melting curve at zero pressure and the calorimetric value for the heat of fusion. The effect of increasing the pressure to 10 000 atm is to reduce the volume of fusion by 30% and to slightly increase the heat of fusion.
Dark Conductivity of Cationic Dye Photoconductors
Authors: Nelson R. C.
Published: January 2005

A theory is put forth to account for the dark conduction in cationic dyes, which assumes thermal excitation from ground state to conductive excited state, followed by trapping of the hole at the anion. It is applicable in principle to any case in which charge carriers are separated by an intrinsic thermal process which is followed by deep trapping of the minority carrier. Where such processes take place, measurements of thermally excited conduction will in general lead to one of three results when interpreted by simple equilibrium theory: the correct activation energy will be found, but the mobility inferred will be impossibly high; or, the mobility will be of the correct order of magnitude, but the activation energy will be too low; or both will be incorrect. The theory is applied to data for dark conduction in eight triphenylmethane dye halides; it is shown to account for the observed thermal activation energies in terms of optical energy levels, and to lead to mobilities which are similar and of acceptable magnitude.
Perturbation Theory and the Hellmann—Feynman Theorem
Authors: Yaris Robert
Published: January 2005

By using the Hellmann—Feynman theorem in conjunction with an operator formulation of perturbation theory it is shown that, while for a general Hamiltonian an energy derivative is determined only to order n by an nth-order wavefunction (Salem and Wilson), for a restricted class of systems it is determined to order n+1, and by restricting the class somewhat further one can obtain energy derivatives to order 2n+1. The example of the force between two atoms interacting through dispersion type forces is briefly discussed.
Hysteresis in the Palladium—Hydrogen System
Authors: Scholtus N. A. , Hall W. Keith
Published: January 2005

When hydrogen is dissolved in palladium, the α phase forms first; the β phase nucleates and grows in this. Because of the large volume change which accompanies the α-to-β transition, plastic deformation of the α phase occurs as it is stretched beyond its elastic limit. Hence, absorption is accompanied by growth of the β phase under compressive stress of the α phase, but desorption take place from the β phase of the plastically deformed solid. Since this is not a thermodynamically reversible process, hysteresis results. It is shown that the absorption loop of the isotherm can be calculated from the desorption loop and the yield strength of the metal. Some reinterpretation of earlier theories is presented.
Crystal-Field Spectra of d3,7 Ions. III. Spectrum of Cr3+ in Various Octahedral Crystal Fields
Authors: Wood D. L. , Ferguson J. , Knox K. , Dillon J. F.
Published: January 2005

The spectra of eight crystals containing trivalent chromium have been measured, and the energy levels fitted to a four-parameter crystal-field theory. The values of the parameters derived from the spectra are discussed, and some mechanisms responsible for absorption intensities are evaluated.
Two-Photon Excitation of Phosphorescence and Fluorescence
Authors: Adelman Albert H. , Verber Carl M.
Published: January 2005

The emission of a charge-transfer complex excited by the two-photon absorption of a laser beam has been investigated. The emission spectra and ratio of phosphorescence to fluorescence have been compared for laser and ultraviolet excitation and are the same indicating that all of the observed processes are the result of the excitation of the charge-tranfer state.
Electron Spin Resonance of Some Arylsulfenyl Radicals
Authors: Zandstra P. J. , Michaelsen J. D.
Published: January 2005

Radicals formed by vapor pyrolysis of β, β′ dinaphthyl and diphenyldisulfide have been studied by electron spin resonance. In each case one of the radicals, identified as the arylsulfenyl radical, shows a large g-value anisotropy in the spectrum. The observed anisotropies are interpreted in terms of the spin—orbit coupling which mixes two states of different orbital angular momentum. The spin densities in one of the states are calculated using a perturbation treatment, according to McLachlan, to allow for the difference in orbitals occupied by different sets of electrons in a nonclosed shell system. The energy differences of the two states are estimated using a molecular orbital approximation. The results indicate that in the ground state of the radical the unpaired electron is localized in a nonbonding orbital of the sulfur.
Second Moments of Electron Spin Resonance Proton Hyperfine Spectra
Authors: Vincow Gershon , Johnson Philip M.
Published: January 2005

The theory of the second moments of ESR spectra of π-electron radicals in polycrystalline environments is discussed and extended. Expressions for the effects of finite linewidth, satellite lines, carbon-13 in natural abundance, g-value anisotropy, and σ-electron spin density are developed. Second moments of a series of aromatic monopositive ion radicals of known spin density distribution are measured and compared with calculated values. The second moment theory is applied to a radical of unknown spin distribution, the benzyl radical. This radical is prepared photochemically and the experimental second moment, 127±6 G2, is compared with values calculated on the basis of a number of valence-theoretical approximations. Closest agreement is obtained for an alternant MO wavefunction [J. Chem. Phys. 32, 176 (1960)] with b/a=0.1. In the course of this investigation the ESR component shape of radicals in single crystals is determined experimentally to be very closely Gaussian. The radical product of the ultraviolet illumination of an aromatic hydrocarbon in a rigid boric acid glass is unambiguously identified by ESR as the aromatic monopositive ion.
Electron Coupling of Nuclear Spins. VII. JFF for 2-Fluorobenzotrifluorides
Authors: Gutowsky H. S. , Mochel V. D.
Published: January 2005

The NMR spectra of several 2-F, 6-X-benzotrifluorides yield values for JFF between the 2-fluorine and the fluorines in the CF3 group of 13 to 34 cps, depending upon the 6-substituent. Furthermore, the magnitude of this JFF is roughly proportional to the chemical shift of the CF3 group and to the size of the 6-substituent. Two related factors appear to be involved: (a) the rotational configuration of the CF3 group with respect to the plane of the benzene ring, and (b) electrostatic deformation of the electron distribution about the fluorines in the CF3 group. Our results for the benzotrifluorides and values reported earlier for the cis-F–CF3 coupling in CF3CX=CFY compounds are consistent with little or no hindrance to CF3-group rotation in the latter.
Drift Velocities of Ions in Nitrogen
Authors: Dahlquist John A.
Published: January 2005

The drift velocities of ions in nitrogen have been measured over very wide ranges of E/p0, the ratio of electric field to pressure reduced to 0°C, under conditions permitting the pressure to be varied separately. The apparatus used consisted of a glow discharge as the ion source, an auxiliary drift space, an electronic shutter, and a final drift space. The readings were taken by measuring the time of flight of the ions across the final drift space. The ion current was amplified and displayed on an oscilloscope. Over a wide range of E/p0 two ion species were present, and these ions are believed to be N2+ and N3+. The N2+ drift velocities varied from 2.5×104 cm/sec at an E/p0 of 20 V/(cm×mm Hg) to 3×105 cm/sec at an E/p0 of 800. The N3+ drift velocity varied from 1.5×104 cm/sec at an E/p0 of 6 to 5×105 cm/sec at an E/p0 of 300.
Isotropic NMR Shifts in Pyridine-Type Bases Complexed with Paramagnetic NiII and CoII Acetylacetonates
Authors: Happe James A. , Ward Raymond L.
Published: January 2005

Isotropic contact interaction shifts in the proton NMR spectra of pyridine-type molecules coordinated with paramagnetic nickel (II) and cobalt (II) acetylacetonates have been observed. The role of π- and σ- bonding frameworks in the transfer of unpaired electron spin density from the metal ion to ligand protons is considered. Pseudocontact interactions appear to be significant in the cobalt systems but not in the nickel systems. When the pseudocontact contribution to isotropic shifts in cobalt systems is factored out there remain contact shifts which are in good agreement with the observed nickel shifts. It is concluded that the unpaired electrons in metal eg orbitals of both cobalt and nickel systems cause contact shifts in the pyridine-type ligands whereas the t2g electron in the cobalt system does not. The t2g electron gives isotropic shifts by contributing to anisotropy in the electronic g factor.
General Acid Catalysis of the Fading of Photoisomerized 2,4-Dinitrotoluene
Authors: Wettermark Gunnar , Ricci Robert
Published: January 2005

Short-lived colored species are formed when a water solution of 2,4-dinitrotoluene is exposed to ultraviolet light. The colored species displayed an acid—base equilibrium and the absorption spectra of the acid form and the base form were measured. The half-life time for the first-order fading reaction was varied over a 105-fold range (20 μsec to 1 sec) by changing the acidity and temperature. The fading reaction was found to be general acid-catalyzed over the pH region 2–13. The experiment supports a mechanism having the following essential features. The nitro form is photochemically isomerized to an aci-nitro form which is in equilibrium with the anion. The rate-determining step in the fading reaction is the neutralization of this anion. The rate constants for the neutralization by various acids have been measured at 30°C to be 1.8×10—2 (H2O), 4.8×103 (HAc), 2.4×104 (+NH3CH2COOH), 7.4×104 (H+) liter sec—1 mole—1.
Polymerization Kinetics of Biological Macromolecules on Templates
Authors: Simha Robert , Zimmerman J. M. , Moacanin J.
Published: January 2005

A kinetics of formation of polymers on linear templates is developed which is applicable to the synthesis of biological macromolecules. Two extreme situations are given theoretical treatment. In both, monomer diffuses to the template surface where polymerization may occur if an adjacent site is suitable occupied. In addition the possibility of monomer desorption is included. In one model (``unrestricted'') the reaction is initiated on each template by the polymerization of two monomers and proceeds through the addition of monomer to growing ends or by the coupling of the growing chains. In the second (``restricted'') model the number of growing centers per template is zero or one and growth is achieved through monomer addition solely. In both cases the template is assumed to be of uniform size and either single stranded or, if double stranded, with an unwinding rate that is rapid in comparison with the polymerization processes. The number of template molecules is assumed constant during the synthesis, which disregards the function of new chains as sites for continued synthesis. All degradation mechanisms are omitted from consideration, which may restrict the present theories to low conversion processes.

The pronounced differences between the unrestricted and restricted formulations in respect to kinetics and product molecular weight are elaborated and discussed in relation to recent experimental results on DNA synthesis in vitro. Finally, from known replication times in vivo, estimates of the rate parameters in the two models are derived.
Dielectric Relaxation in the 1-Propanol-2-Methylpentane System
Authors: Denney D. J. , Ring J. W.
Published: January 2005

Dielectric relaxation in the 1-propanol-2-methylpentane system has been studied at eight concentrations down to 14.3 mole % alcohol and over the temperature range in which dispersion occurs in the audio—radio-frequency region. Above 50 mole % alcohol the primary dispersion is characterized by a single relaxation time and the secondary dispersion is relatively small, accounting for about 5% of the total. Below this concentration, the primary dispersion becomes increasingly asymmetric with dilution and the second dispersion increases in amplitude relative to the first. A ring—chain—monomer equilibrium is postulated to account for the increasing relative importance of the secondary dispersion with increasing dilution and decreasing temperature.
Modification to the Newton—Raphson Method for the Fitting of Nonlinear Functions by Least Squares
Authors: Strand T. G. , Kohl D. A. , Bonham R. A.
Published: January 2005

A modification to the regularly used methods for the fitting of nonlinear functions by least squares is presented. The modified method converges in fewer cycles of the iterative solution than the unmodified Newton—Raphson method, and in certain cases, the modification makes the iteration converge from starting vectors for which the unmodified method diverges. A numerical example is given, where the modification is used with the Newton—Raphson method to obtain an analytical expression for the Thomas—Fermi—Dirac potential function of an atom. The solutions from the modified method are discussed in relation to the results of the unmodified ones for different starting values of the parameters.
Nuclear Spin—Spin Coupling Involving Heavy Nuclei. The Coupling between Hg199 and H1 Nuclei in CH3HgX and CH3CH2HgX Compounds
Authors: Hatton J. V. , Schneider W. G. , Siebrand W.
Published: January 2005

Nuclear spin coupling between protons and Hg199 nuclei in CH3HgX and CH3CH2HgX compounds has been investigated. As the X substituent is made more electronegative very large increases in the spin-coupling constant up to 2½-fold were observed. Smaller alterations occur in different solvent media, and alkyl exchange could be observed in several compounds. In the CH3CH2HgX compounds the changes in the spin-coupling constants of the Hg nucleus with the protons in the methylene group and in the methyl group are comparable in magnitude. The results are interpreted in terms of a simplified model for contact interaction employing optical hyperfine structure (hfs) constants. Qualitative arguments are employed to assess the relative importance of other coupling mechanisms. It is concluded that spin coupling arising from electron orbital motion is negligible, and while dipole—dipole contributions may be important, the evidence indicates the Fermi contact interaction is the dominant coupling mechanism.
ESR Measurement of Spin Susceptibility of Graphite in a Low Magnetic Field
Authors: Wayne R. C. , Cotts R. M.
Published: January 2005

The spin susceptibility of pure crystals of natural graphite has been measured by comparing the integrated intensity of the electron spin resonance signal to the intensity of the nuclear magnetic resonance of a known amount of aluminum powder mixed with the graphite sample. Both resonances were observed by using a crossed-coil nuclear induction probe at 12.8 Mc/sec. At 300°K, the spin susceptibility is found to be (1.44±0.3) × 10—8 cgs units per gram in agreement with known microwave measurements and theory. The apparent g value of low-field resonances observed with the crossed-coil probe is briefly discussed.
Numerical Solutions of the Convolution-Hypernetted Chain Integral Equation for the Pair Correlation Function of a Fluid. I. The Lennard-Jones (12, 6) Potential
Authors: Klein Max , Green M. S.
Published: January 2005

The integral equation of the convolution-hypernetted chain approximation is solved numerically at five temperatures for the Lennard-Jones (12, 6) potential. Due to an inconsistency in the approximation there are two equations of state associated with it. These are compared with each other, with other theories, and with the experimental argon equation of state. At high temperatures, the two equations of state agree both with experiment and with more a priori theory at low densities and bracket them at higher densities, their mean giving a good representation of both. The integral equation is found to be singular at certain temperature—density points, their locus forming a dome shaped curve in the T—ρ plane. These points are shown to correspond to the limits of metastability in the van der Waals gas, the highest temperature point being the critical point. The nonsingular points below the critical point correspond either to a homogeneous gas (low densities) or liquid (high densities) phase. The former are in good agreement with the three-term virial series, as expected, and the latter are a considerable improvement over it. The equation of state is a considerable improvement over that obtained from the Born—Green equation by Kirkwood, Lewinson, and Alder, the latter predicting negative pressures over most of the liquid range while these results show only positive pressures. The comparisons with experiment are obscured by the inadequacy of the (12, 6) potential function. The use of temperature ``compensated'' potential parameters (as determined by the second virial coefficient) indicates that the use of a more reasonable potential function in the theory will give a relatively good representation of the equation of state of a fluid over a wide range of temperatures and densities.
Observation of Fluorescence in Ketone Solutions of Europium and Terbium Salts
Authors: Matovich E. , Suzuki C. K.
Published: January 2005

Relatively long-lived fluorescence has been observed in simple ketone solutions of europium and terbium salts at room temperature without any deliberate formation of chelates or other complexes. Emission and absorption spectra of the solutions are presented, as well as the effects of dilution and water content on their fluorescent output. The temperature behavior of the fluorescent output and lifetime is also shown.
Magnetic Characteristics of Tb–Y and Ho–Y Solid Solutions
Authors: Weinstein Sidney , Craig R. S. , Wallace W. E.
Published: January 2005

Magnetization—temperature data are presented for temperatures ranging from 4.2° to 300°K for Tb–Y and Ho–Y solid solutions in which the Y content varies from 0 to 90 at. %. Incorporation of Y into the Tb lattice suppresses the tendencies for both ferromagnetic and antiferromagnetic ordering. The former in particular is affected so that alloys containing 70% Tb or less no longer exhibit ferromagnetism in the absence of an applied field. The Néel point (TN) is lowered when Ho is diluted with Y but the temperature of its lower magnetic transition point (sometime called its Curie point) is essentially unchanged. TN32 is observed to vary linearly with composition in both the Tb–Y and Ho–Y systems. The paramagnetic behavior of both systems is in general accordance with that expected on the basis of the simple molecular field picture. The magnetization—temperature behavior of Tb70Y30 is anomalous, resembling that of Dy90Y10 and Dy95Y5. Under certain circumstances these alloys appear to be magnetically two phase.
Molecular Orbital Studies of Excited States of HeH
Authors: Michels H. H. , Harris F. E.
Published: January 2005

The total energy of HeH was computed using a method of molecular orbital calculation in which the total wavefunction is taken as a linear combination of configurations, each a properly antisymmetrized product of flexible one-electron functions in an elliptic coordinate system. We have examined the lowest 2Π state of this system and both of the 2Σ excited states which arise from the interaction of ground-state He and a 2p or 2s H atom. The lowest 2Π state of HeH and the first excited 2Σ state are found to be bonding with calculated dissociation energies of 1.935 and 2.336 eV, respectively. A comparison of these results with those previously reported for the ground state of HeH and the molecular ion HeH+ indicates that the charge distribution about the helium atom is similar in all of these systems and it is predicted that, with the single exception of the ground state, all of the doublet states of HeH up to the ionization limit of the H atom are bonding and can be represented by very similar potential energy curves.
Radiation Decomposition of Aqueous Nitrite Solution Containing Mercuric Salts
Authors: Shinohara Kenichi , Shida Tadamasa , Saito Nobufusa
Published: January 2005

Aqueous sodium nitrite solutions containing mercuric salts give mercurous salts when irradiated with Co60 γ rays. The G value of mercurous salt attains to such a high value over a wide range of solute concentration that the accepted radical yields cannot account for.

In order to settle the apparent contradiction it is suggested that in a spur several excited water molecules may be produced and that they can react with nitrite ions to form excited complexes which can reduce mercuric into mercurous salt.
Photolysis of Aqueous Azide Solution Containing Mercuric Salts
Authors: Shinohara Kenichi , Shida Tadamasa , Saito Nobufusa
Published: January 2005

The previous study of photolysis of sodium azide plus mercuric chloride solution has been extended to the solutions of sodium azide plus several mercuric salts. The yield of photolysis is given as a function of solute concentrations. From the measurement of light intensity it is found that the photolysis is not a chain reaction as stated in the previous paper.
A Variation-Perturbation Approach to the Interaction of Radiation with Atoms and Molecules
Authors: Karplus M. , Kolker H. J.
Published: January 2005

A variation-perturbation formulation for time-dependent interactions is presented and applied to the interaction between atoms or molecules and a semiclassical radiation field. Details of the treatment through second order are given for the steady-state problem and are compared with the standard perturbation-theory results. It is demonstrated that the usual expression for the time-dependent perturbation solution, which consists of a sum over an infinite set of excited states (including any continuum), can be replaced by a small number of frequency-dependent functions that satisfy certain time-independent differential equations. Since an exact solution to these equations is very difficult for all but the simplest cases, an equivalent variational formulation of more general utility is introduced.

The induced time-dependent electric and magnetic moments of atoms and molecules in an oscillating electromagnetic field are evaluated in terms of the frequency-dependent functions. With the usual continuum medium assumptions, the macroscopic polarizations are determined from these moments, and simple formulas for the index of refraction and optical rotatory power are obtained. The method is illustrated by a simple application to the dynamic polarizability of the harmonic oscillator and by a more detailed examination of the dynamic polarizability and index of refraction of the nonrelativistic hydrogen atom. A comparison is made between an exact solution and a variational approximation for this problem. The excellent agreement between the two methods provides an indication of the power of the variational formulation. An indication of its utility for more general applications is given.
HFS Constants of OH Ground State
Authors: Kayama Kunifusa
Published: January 2005

Fermi contact term at the proton in the OH ground state is pointed out to be negative either from a simple qualitative consideration or from an LCAO MO CI calculation. The calculated value agrees well with the experimental value revised recently by Radford. Other hfs constants, 〈1/r3〉H and 〈2P2(cosχ)/r3〉H, are also calculated by a single configuration approximation with the use of an analytical Hartree—Fock orbital. The results agree quite well with the experiment, although the agreement is somewhat worse for 〈sin2χ/r3〉H.
Assignment of NMR Spectra with the Aid of Double-Quantum Transitions
Authors: Anderson W. A. , Freeman R. , Reilly C. A.
Published: January 2005

The analysis of complex nuclear magnetic resonance spectra usually requires the assignment of the observed transition to an energy-level diagram. It is shown that double-quantum transitions can be used to determine such an assignment. Small frequency shifts of the double-quantum transitions have been observed and their dependence upon the strength of the applied radio-frequency field measured and compared with theory. The double-quantum method is compared to the double resonance method in making an energy-level assignment using the 60-Mc/sec spectrum of trivinylphosphine for the purposes of illustration. The analysis has been completed by an algebraic method and by iteration on a computer, and the results checked by recording the 100-Mc/sec proton spectrum and the 19-Mc/sec P31 spectrum. The three proton—proton couplings and the three P31 proton couplings all have the same sign.
Effect of Pressure and Temperature on Rotational Isomeric Relaxation in Ethyl Acetate
Authors: Slie Warren M. , Litovitz Theodore A.
Published: January 2005

Ultrasonic absorption measurements have been made in liquid ethyl acetate over a temperature range from 10° to 80°C and up to a pressure of 1000 atm. Evidences of a rotational isomeric relaxation were observed, and the relaxation frequency fr was calculated as a function of temperature and pressure. The relaxation frequency was found to be independent of pressure (within experimental error) up to 1000 atm and to increase exponentially with increasing temperature. The activation enthalpy was found to be in good agreement with that found previously by Pinkerton. The calculated values of fr at 40°C are also in good agreement with Pinkerton and those of Kal'yanov and Nozdrev. However, the data taken at constant density as a function of temperature are in complete disagreement with the conclusions of Kal'yanov and Nozdrev who find that at constant density fr is independent of density but dependent on temperature.
Some Relations between the Supercooling and the Structure of Aqueous Solutions
Authors: Pruppacher Hans R.
Published: January 2005

An experimental method has been devised to determine the effect of water-soluble substances on the supercooling of pure water. It was found that solutes influence the supercooling of water in a systematic manner. The nonequilibrium freezing-point depression of a solution (Δt)f varied with the type of solute and, for a particular solute, increased with increasing solute concentration. The depression (Δt)f could be related to the equilibrium freezing point depression of the solution (Δt)e, the supercooling of water (Δt)w and a supercooling increment δ which depended on the type of solute. Some relations between the experimental results and the structure of aqueous solutions are discussed.
Lattice Vibrations and Specific Heats of Several Rare-Earth Ethylsulfates
Authors: Wong Eugene Y. , Erath Edward H.
Published: January 2005

The vibronic absorption spectra of praseodymium, neodymium, and erbium ethylsulfate were used to construct tentative vibrational energy-level diagrams for the crystals. With this technique, 42 levels ranging from 18 to 360 cm—1 were identified. The energy-level spectra were used to calculate the specific heat of the crystals from 0° to 15°K as an additional check on the origin of the observed absorption spectra and fair to good agreement with measured specific heats was achieved.
Rotational Transition and Self-Diffusion in Polycrystalline Succinonitrile
Authors: Petrakis L. , Rao A.
Published: January 2005

The H1 NMR spectrum of polycrystalline succinonitrile has been recorded as a function of temperature. The observed narrowings of the spectral width are explained in terms of rotation and self-diffusion of the succinonitrile molecules.
On the Mechanism of the Pyrolysis of Neopentyl Chloride
Authors: Anderson Kenneth H. , Benson Sidney W.
Published: January 2005

The pyrolysis of neopentyl chloride has been reported to decompose by an ion-pair mechanism in a gas-phase homogeneous reaction at about 450°C. It is shown that a Rice—Herzfeld mechanism involving the principal radical chain: Cl+(CH3)3CCH2Cl→ lim 2HCl+(CH3)2C(CH2)(CH2Cl),[Complex chemical formula]accounts well for the products and rate. It is followed by the fast unimolecular isomerization of 1,1-dimethyl cyclopropane to the isomeric methylbutenes. It is shown that the system is quite complex, involving autocatalysis by HCl (one of the major products) and very likely inhibition by the concomitantly produced olefins.
Hydrogen-Chloride-Catalyzed Pyrolysis of Dimethyl Ether and the Use of HCl Catalysis for Diagnosis of Complex Chains
Authors: Anderson Kenneth H. , Benson Sidney W.
Published: January 2005

The pyrolysis of CH3OCH3, catalyzed by gaseous HCl (3 to 16 mole %) has been studied in the temperature range 452° to 483°C. The rate approaches independence of HCl at the higher concentrations and is 3/2 order in ether. The products are the same as in the uncatalyzed decomposition (CH4+CO+H2 and CH4+CH2O) and no HCl is consumed. From the observation that there is up to a tenfold acceleration in rate with HCl it is shown that the slow step in the uncatalyzed pyrolysis is the reactionCH3+CH3OCH3→ lim 2CH4+CH2OCH3.The hitherto-conceived slow step CH2OCH3→ lim 3CH2O+CH3resulting from the analysis of S. W. Benson and D. V. S. Jain [J. Chem. Phys. 31, 1008 (1959)] is instead very rapid, and thus CH2OCH3 cannot be an important chain breaker.

Recent data on the stability of HCO indicate that CH3 and CHO are the actual chain-breaking radicals, both being important in the uncatalyzed decomposition. The H2S catalyzed reaction is discussed briefly and shown to be similar to the HCl system. HCl catalysis as a diagnostic tool in analyzing complex chains is discussed.