bluuebunny/crossref_metadata_2025 huggingface dataset:
Raman and Infrared Spectral Data and Tentative Assignments for cis- and trans-Diiodoethylene
Authors: Miller Sidney I. , Weber Alfons , Cleveland Forrest F.
Published: April 2005

Raman displacements, relative intensities, and depolarization factors, as well as wave numbers and estimated relative intensities for the infrared absorption bands in the region 400—4000 K (K = kayser = cm—1), have been obtained. Tentative assignments are given for the observed wave numbers and the applicability of the sum and product rules of Mizushima and Bernstein is discussed.
Near Infrared Spectrum of Nitric Oxide
Authors: Nichols Nathan L. , Hause C. D. , Noble R. H.
Published: April 2005

The 2—0 and 3—0 vibration-rotation bands of NO at 2.69 μ and 1.8 μ have been obtained and measured. The envelope of the 4—0 band at 1.36 μ was obtained. Careful reduction of the data yields the following rotational constants: B0=1.6965 cm−1B2=1.6631 cm−1B3=1.6408 cm−1Be=1.7060 cm−1αe=0.0180 cm−1Ie=16.404×10−40 g cm2re=1.1503×10−8 cm
Low-Temperature Absorption Spectra of Selected Olefins in the Farther Ultraviolet Region
Authors: Potts W. J.
Published: April 2005

A ``red shoulder'' on the N ← V absorption curve of olefins, observed at room temperature, but not at low temperature, results from the fact that the potential curves for twist about the double bond in the ground and excited states have slopes of opposite sign. The weaker absorption in the region 40—48 000 cm—1 is assigned to the N ← T absorption on the basis of its analogy to the N ← V transition in position, extinction coefficient, and oscillator strength.
Modified Valence-Bond Treatment of Unsaturated and Aromatic Compounds
Authors: Wheland G. W.
Published: April 2005

The conventional valence-bond treatment, by being put upon a more frankly empirical basis, can be modified in such a way that the difficulties arising from the nonorthogonality of the atomic orbitals centered about different atoms are largely bypassed. Although the extension of the new treatment to molecules more complex than that of benzene is rendered impracticable by the increased mathematical difficulties, the results obtained for 1,3-butadiene, cyclobutadiene, and benzene suggest that many of the essential features of the older calculations can be given a better theoretical justification than hitherto seemed possible. On the other hand, the importance of the relatively unstable structures with formal bonds appears to have been overrated.
Appearance Potential Studies. II. Nitromethane
Authors: Kandel Richard J.
Published: April 2005

Appearance potentials and excess kinetic energies have been determined for the ions produced by the ionization and dissociation of nitromethane by electron impact in a mass spectrometer. Bond dissociation energies and mechanisms of fragmentation have been deduced where possible. D(CH3–NO2) has been found to be 2.56 volts, a value in agreement with thermochemical data. The dissociation and ionization process yielding NO+, the most abundant ion in the nitromethane mass spectrum, is believed to yield, at the same time, a CH3O radical. A new value for the ionization potential of NO2, 9.91 volts, is reported.
Measurement of the Molecular Weights of Vapors at High Temperature. II. The Vapor Pressure of Germanium and the Molecular Weight of Germanium Vapor
Authors: Searcy Alan W. , Freeman Robert D.
Published: April 2005

The vapor pressure of germanium and the molecular weight of germanium vapor have been determined by use of an apparatus for the simultaneous measurement of the weight of vapor effusing through two small orifices and of the force exerted by the effusing vapor. The molecular weight of germanium vapor at 1750°K was found to be 58±16 compared to the atomic weight of 72.60. The heat of sublimation of germanium at 298°K is 91.5±3.0 kcal.
Chemical and Photochemical Studies on 6,8-Thioctic Acid and 1,2-Dithiolane (Trimethylene Disulfide)
Authors: Whitney R. B. , Calvin Melvin
Published: April 2005

Quantum yields have been determined in the photolysis of thioctic acid and trimethylene disulfide by ultraviolet light under a variety of conditions. The order of magnitude of the quantum yield is unity.
Dielectric Properties of Liquid Ethanol and 2-Propanol
Authors: Hassion F. X. , Cole R. H.
Published: April 2005

Dielectric constants and loss were measured from room temperature to —160°C for the pure liquids and mixtures with small amounts of water to facilitate supercooling. Two distinct dispersion regions were found below —100°C in the experimental frequency range from 1 cy/sec to 5 Mc/sec. The temperature dependences are similar and described by rate laws of the form found for similar measurements in 1-propanol. An explanation of the multiple dispersions in terms of hydrogen bond breaking to permit reorientation of alkyl and hydroxyl groups is discussed.
Excited Triplet States of Polyatomic Molecules. II. Flash-Lamp Studies on Aromatic Ketones
Authors: McClure Donald S. , Hanst Phillip L.
Published: April 2005

The apparatus for observing triplet-triplet transitions in polyatomic molecules is the same as in part I except that resonance lamps are here replaced by a flash lamp. Triplet-triplet spectra are reported for benzophenone, acetophenone, β-bromo and β-iodo naphthalene. No triplet-triplet absorption was found in benzene, biacetyl, acetone dibromo benzene, or diisopropyl ketone. Detailed studies of the energy levels of benzophenone and acetophenone are reported.
Oxygen-18 Isotope Effect in the Reaction of Oxygen with Copper
Authors: Bernstein Richard B.
Published: April 2005

The fractionation of oxygen-18 in the reaction of copper with oxygen of natural isotopic composition has been measured over the temperature range 68—256°C. The oxide films (estimated thicknesses varying from 150—2500 A) were removed for O18 assay by treatment with hydrogen at 350°C. Using the CO2 equilibration technique, the O18/O16 ratios for the resulting water samples were determined mass spectrometrically and compared with the ratio for a reference sample of water prepared from the original oxygen gas.

The direction of the fractionation indicated that O216 reacts preferentially compared to O16O18. The isotope effect appeared to be independent of the oxygen pressure over the limited range studied (2—25 cm Hg). The magnitude of the fractionation factor was 2.0% at 150°C, with a small negative temperature coefficient. From this it was possible to estimate a value of ΔEact=17 cal/mole, which may be compared with the calculated isotopic zero-point energy difference of 64 cal/mole. The theoretical implications of the experimental results are discussed.
Heat Capacity and Entropy of FeF2 and CoF2 from 11 to 300°K. Thermal Anomalies Associated with Antiferromagnetic Ordering
Authors: Catalano Edward , Stout J. W.
Published: April 2005

The heat capacities of FeF2 and CoF2 have been measured between 11 and 300°K. Both salts show anomalies in heat capacity associated with the antiferromagnetic ordering of the magnetic ions. The heat capacity of FeF2 exhibits a sharp maximum of 17.8 cal deg—1 mole—1 at 78.35°K and that of CoF2 has a maximum of 5.64 cal deg—1 mole—1 at 37.70°K. Values of the heat capacity, entropy, enthalpy, and free energy are tabulated at selected temperatures. The values of the entropy and enthalpy at 298.16°K are: FeF2, S0=20.79±0.04 cal deg—1 mole—1, H0–H00=3049±6 cal mole—1; CoF2, S0=19.59±0.04 cal deg—1 mole—1, H0–H00=2978±6 cal mole—1.
Interaction Energy among Three Helium Atoms
Authors: Shostak Arnold
Published: April 2005

Molecular orbitals made up of linear combinations of atomic orbitals, as well as orbital, total, and interaction energies, have been calculated for the linear configuration of three He 1 — s atoms, with equal separation between the center and each outer atom. Roothaan's self-consistent field matrix method was applied to this case. All electronic interactions were considered, their contributions appearing in the Hamiltonian used in solving for total energy. The assumption of additivity of the energies of all pairs of atoms in determining interaction energy is shown not to be valid for internuclear separations approaching collision diameter of the 1 — s He atom, about 1 A. Deviation from additivity, as determined using the results of Wehner's MO calculation for the system He2 is about 30% for the smallest internuclear separation considered, around 0.93 A.
Electronic Structures of Transition-Metal Complexes
Authors: Orgel L. E.
Published: April 2005

The empirically determined values of the parameter Dq, which in transition-metal complexes, measure the influence of the ligands on the metal d-orbitals are interpreted theoretically. A quantitative treatment of ``the magnetic criterion of the bond type,'' is given. Values of Slater-Condon parameters for transition metal ions are tabulated.
Electronic Population Analysis on LCAO–MO Molecular Wave Functions. I
Authors: Mulliken R. S.
Published: April 2005

With increasing availability of good all-electron LCAO MO (LCAO molecular orbital) wave functions for molecules, a systematic procedure for obtaining maximum insight from such data has become desirable. An analysis in quantitative form is given here in terms of breakdowns of the electronic population into partial and total ``gross atomic populations,'' or into partial and total ``net atomic populations'' together with ``overlap populations.'' ``Gross atomic populations'' distribute the electrons almost perfectly among the various AOs (atomic orbitals) of the various atoms in the molecule. From these numbers, a definite figure is obtained for the amount of promotion (e.g., from 2s to 2p) in each atom; and also for the gross charge Q on each atom if the bonds are polar. The total overlap population for any pair of atoms in a molecule is in general made up of positive and negative contributions. If the total overlap population between two atoms is positive, they are bonded; if negative, they are antibonded.

Tables of gross atomic populations and overlap populations, also gross atomic charges Q, computed from SCF (self-consistent field) LCAO-MO data on CO and H2O, are given. The amount of s-p promotion is found to be nearly the same for the O atom in CO and in H2O (0.14 electron in CO and 0.15e in H2O). For the C atom in CO it is 0.50e. For the N atom in N2 it is 0.26e according to calculations by Scherr. In spite of very strong polarity in the π bonds in CO, the σ and π overlap populations are very similar to those in N2. In CO the total overlap population for the π electrons is about twice that for the σ electrons. The most easily ionized electrons of CO are in an MO such that its gross atomic population is 94% localized on the carbon atom; these electrons account for the (weak) electron donor properties of CO. A comparison between changes of bond lengths observed on removal of an electron from one or another MO of CO and H2, and corresponding changes in computed overlap populations, shows good correlation. Several other points of interest are discussed.
Electronic Population Analysis on LCAO–MO Molecular Wave Functions. II. Overlap Populations, Bond Orders, and Covalent Bond Energies
Authors: Mulliken R. S.
Published: April 2005

LCAO molecular orbital overlap populations give in general much more flexible and widely useful measures of the non-Coulombic parts of covalent bond energies than do LCAO bond orders. They are immediately applicable to both π and σ bonds, including bonds involving hybrid AOs of all kinds, and they take account directly of the effects of variations in bond length on bond strength. In the last section of this paper, a number of ways of defining LCAO bond orders are reviewed, and their advantages and disadvantages discussed.

If all LCAO parameters β are assumed proportional to corresponding overlap integrals S times suitable mean atomic ionization energies Ī, a simple general approximate formula for covalent resonance energies is obtained in terms of partial overlap populations and Ī's, including one or two empirical coefficients. This formula indicates that forced hybridization (see III of this series) due to inner shells should make important negative contributions to bond energies. The application of the formula to H2, CO, and H2O is discussed.

The assumption of proportionality of β values to SĪ values may be useful also in estimating unknown β values.
Self-Diffusion of Liquid Sodium
Authors: Meyer R. E. , Nachtrieb N. H.
Published: April 2005

The self-diffusion of liquid sodium in the temperature range, 98° to 226°, has been studied by the capillary reservoir technique. The data fit the empirical equation, D=1.10×10—3 exp (—2430/RT). The Stokes-Einstein equation gives a good correlation of the self-diffusion and viscosity data. The difference in the self-diffusion coefficients of the solid and liquid sodium is explained in terms of the ``relaxation'' theory of diffusion proposed by Nachtrieb and Handler.
Structures of CF3Cl and CH3Cl
Authors: Bartell L. S. , Brockway L. O.
Published: April 2005

The molecular structures of CF3Cl and CH3Cl were determined by refined procedures of electron diffraction. For CF3Cl, the most probable C–F and C–Cl distances are 1.328 A and 1.751 A respectively and ∠FCF=108.6°. Results for CH3Cl agree with the complete microwave determination. Vibrational amplitudes are in agreement with approximate calculations by Morino.
Use of the Lattice Model for Entropy Calculations
Authors: Bueche F. , Krigbaum W. R.
Published: April 2005

The influence of choice of cell size upon the calculated entropy of mixing of solutions is discussed. It is shown that the lattice type calculation, when properly applied, leads to the same result for all possible choices of cell size. A new method is presented for calculating the entropy of mixing which does not assume a lattice. This method confirms the result of the lattice calculation.
Gaseous Detonations. VII. A Study of Thermodynamic Equilibration in Acetylene-Oxygen Waves
Authors: Kistiakowsky G. B. , Zinman Walter G.
Published: April 2005

The observed detonation velocities in acetylene-oxygen mixtures containing from 5 to 50% acetylene and thermo-hydro-dynamic calculations which assume complete equilibrium to be attained in the Chapman-Jouguet plane agree within 0.5%. This is of special interest because in successive parts of this composition range each of the several reactions, viz. dissociation of excess oxygen, carbon dioxide, water, and hydrogen becomes the main endothermic process. Temperatures may be calculated from the detonation velocities which agree with the theoretical equilibrium values to better than 1% over the range from 3000 to 4500°K.

In acetylene-oxygen mixtures containing 53 and 55% of the former, the observed detonation velocities agree with equilibrium calculations only when it is assumed that undersaturated carbon vapor, taken to be in equilibrium with unburned acetylene, has 170 Kcal as its heat of sublimation.

The velocities in mixtures containing from 60 to 70% acetylene agree quite well with calculations assuming homogeneous equilibrium. However, supersaturation of carbon vapor with respect to the solid must be assumed.

In mixtures containing 71% acetylene a sudden rise in detonation velocity is observed partway down the tube. The final velocity, as well as the constant velocities in still richer mixtures, are consistent with calculations assuming complete equilibrium, including solid carbon.

The discontinuity observed with 71% mixtures is interpreted as the overtaking of the Chapman-Jouguet plane of the primary detonation wave by a secondary shock wave developed by the delayed precipitation of carbon. It is suggested that because of the dependence of the delays of nucleation on the degree of supersaturation of a vapor, high velocities corresponding to complete equilibrium could be observed with leaner mixtures also, if detonation velocities were measured far enough from the point of initiation.
Far Ultraviolet Absorption Spectra of Ethylene and Ethylene-d4
Authors: Wilkinson P. G. , Mulliken R. S.
Published: April 2005

The absorption spectra of ethylene and ethylene-d4 have been reinvestigated in the 1500 A to 2050 A region, using the first order of the Harrison 21-foot vacuum spectrograph. Vibrational constants of the C=C stretching vibration in the R (first Rydberg) state were determined to be: C2H4, ω20=1381.5 cm—1; x220=—11.2 cm—1; C2D4, ω20=1306.8 cm—1; x220 —8.2 cm—1; and (tentatively) in the V state: C2H4, ω20=852 cm—1; x220=—1.9 cm—1; C2D4, ω20=797 cm—1; x220=—1.8 cm—1. Newly observed fine structure in the v′—0 stretching vibration progression in the long wavelength part of the V←N transition of C2D4 is tentatively attributed to a torsional oscillation. The 0—0 bands of the V←N transition, though too weak to be seen, were estimated to lie near 2500 A. The probable dissociation of ethylene into CH2 radicals in the V←N continuum is discussed.

The torsional frequency in the R state was redetermined as 141 cm—1 (C2D4) and 236 cm—1 (C2H4), decreasing somewhat with increasing stretching quantum number. An attempt has been made to fit the corresponding vibrational levels, for both isotopes, to those calculated for a torsional oscillator-rotator using a potential function of the form V=12V0(1+cos2θ). Rough agreement is obtained for a reasonable barrier height of about 790 cm—1. (Values of 650 cm—1 for C2D4 and 920 cm—1 for C2H4 are obtained when the two isotopes are treated separately.) The anomalous isotope effect and intensities in the R←N twisting bands are tentatively attributed to perturbation of the R state levels by V state levels and/or the departure of the twisting potential from the simple cosine form. These views are encouraged by the fact that a higher Rydberg state shows similar twisting bands but with much less anomalous isotope effect and intensities.
Infrared and Raman Spectra of 1,1,2,2-Tetrachloroethane; Calculation of Normal Vibrations
Authors: Naito Kazuo , Nakagawa Ichiro , Kuratani Kenji , Ichishima Isao , Mizushima San-ichiro
Published: April 2005

Infrared spectra of 1,1,2,2-tetrachloroethane have been measured in the gaseous, liquid, and solid states and in solutions. Raman spectra of the same substance have been observed in the liquid and solid states. From the experimental results the equilibrium molecular forms of the rotational isomers have been determined. The normal vibrations of the molecule in the trans- and gauche-forms have been calculated as an 8-body problem, and the assignment of the observed infrared and Raman frequencies in all the states of aggregation has been made.
Internal Pressure of Carbon Tetrachloride between —7° and 70°
Authors: Benninga Harm , Scott Robert L.
Published: April 2005

Measurements of (∂P/∂T)V of carbon tetrachloride at ten different temperatures between —7° and 70°C yield an equation for the internal pressure (∂E/∂V)T=3346[1—2.97×10—3(t—25)—12.6×10—6(t—25)2] atmospheres.

Comparison with the cohesive energy density (ΔEv/V) confirms previous observations (Hildebrand and co-workers) that the ratio of the internal pressure to the cohesive energy density is approximately unity and further shows this ratio to be remarkably constant over the entire 77° range of temperature.

The experimental data on the internal pressure are in marked disagreement with the predictions of ``free-volume theory'' (Lennard-Jones and Devonshire, Hirschfelder and co-workers).
Grüneisen's Constant for Some Metals
Authors: Gilvarry J. J.
Published: April 2005

The Grüneisen constants, as evaluated from compressibility parameters, are redetermined for the alkali metals Li, Na, and K and are determined for Rb and Cs from experimental data of Bridgman, and are shown to be in good agreement with the corresponding values as evaluated from Grüneisen's law. In the cases of Au, Mo, Ta, and Mn, previous work by Slater had shown a large discrepancy between these two evaluations of the Grüneisen constant. The discrepancy is largely removed for Au by a redetermination of the Grüneisen constant from more recent compressibility data of Bridgman. The disagreement persists for Mo (to some degree), and for Ta (where the disparity is large); the results for Mn are inconclusive. A redetermination for Al brings closer agreement than previously between the two evaluations of the constant. The bearing of the results for compressibility parameters on some semiempirical equations of state is indicated.
Vibrational Spectrum of Fluorotrichloroethylene
Authors: Mann D. E. , Plyler Earle K.
Published: April 2005

The infrared spectrum of gaseous fluorotrichloroethylene, FClC:CCl2, has been obtained in the range 3—50 microns. The Raman spectrum of a liquid sample has also been determined. Earlier data and new force constant calculations for some other fluorochloroethylenes are reviewed and used to establish a satisfactory vibrational assignment for FClC:CCl2. The planar fundamentals appear at 1645, 1181, 988, 857, 520, 407, 358, 250, and 174 cm—1; the out-of-plane vibrations occur at 537, 313, and probably near 130 cm—1. A necessary revision in the existing assignment for F2C:CCl2 is indicated. A table of the thermodynamic functions is given for FClC:CCl2 in the ideal gaseous state.
Concerning the Temperature Coefficient of the emf of Reversible Galvanic Cells Operated at Variable Concentration. II
Authors: Li James C. M.
Published: April 2005

The general expression including concentration coefficients of the emf of the cell is derived for an open system. The limitation in the application of the Gibbs-Helmholtz equation is further discussed in general with additional examples.
Regularities in the Absorption Spectra of Halides
Authors: Katzin Leonard I.
Published: April 2005

Original absorption spectra of halides and a large body of literature absorption spectrum data are assembled. Certain characteristic features are pointed out which can be ascribed to transitions of electrons localized on the halide portion of a molecule or ion, such that their removal to an excited condition essentially leaves a neutral halogen atom as part of the excited state configuration. Recognition of this portion of the spectrum should assist understanding of halide spectra.
Hybrid π Orbitals and Partial Double Bond Character in Covalent Complexes
Authors: Giacometti Giovanni
Published: April 2005

Angular parts of p- and d-orbitals are hybridized to form a set of tetrahedrally oriented π orbitals. These orbitals are suitable for explaining partial double bond character in compounds such as nickel tetracarbonyl. It is shown that up to three of these orbitals may exist, each possessing the required properties of orthogonality and linear independence. The maximum partial double bond character allowed is, in this way, 75%. The strength of these orbitals, according to a modified Pauling's criterion, is discussed. Also the cases of trigonal bipyramidal and octahedral symmetry are discussed. An attempt is made to interprete semiquantitatively bond lengths in Cr, Fe, and Ni carbonyls.
Localizability of Electrons in Atoms and Molecules—Application to the Study of the Notion of Shell and of the Nature of Chemical Bonds
Authors: Daudel Raymond , Brion Hélène , Odiot Simone
Published: April 2005

The importance of the correlations existing between the positions of electrons in atoms and molecules has recently been stressed. A new method for the study of these correlations is presented here. It consists in the decomposition of the space of an electronic system into small parts where there is a very large probability of finding one and only one electron of a given spin. This method allows the association of spherical rings to the shells of atoms and the association of space to the atomic core and to the bonds of molecules.
On the Origin of the Electronically Excited C2* Radical in Hydrocarbon Flames
Authors: Ferguson R. E.
Published: April 2005

An isotopic tracer experiment, using carbon 13, has been performed to determine whether the excited C2 radical in acetylene flames comes directly from the carbon pair of the acetylene burned. In the flame studied, the greater part of the C2* which radiates does not come from this source, but is produced in some series of reactions in which the —C≡C— bond is broken prior to the appearance of C2*. It is shown further that most of the C2* cannot arise from the random breakup of polymers or incipient carbon particles formed by direct polymerization of acetylene. The results appear to favor the choice of a reaction between single-carbon fragments as the predominant source of C2*.
Infrared Spectra and Structure of the Crystalline Sodium Acetate Complexes of U(VI), Np(VI), Pu(VI), and Am(VI). A Comparison of Metal-Oxygen Bond Distance and Bond Force Constant in this Series
Authors: Jones Llewellyn H.
Published: April 2005

Infrared spectra of solid NaXO2(Ac)3, with X=U, Np, Pu, and Am, have been observed. From the symmetric and asymmetric stretching frequencies of the O–X–O groups, approximate X–O force constants have been calculated and were found to decrease in the order kU—O>kNp—O>kPu—O> kAm—O, the respective values being about 0.705, 0.698, 0.675, and 0.612 megadyne/cm. From the cell constants for NaXO2(Ac)3 it is apparent that the X–O bond distance decreases in the same order—RU—O>RNp—O>RPu—O>RAm—O. Thus, a decrease in bond distance appears to be accompanied by a decrease in force constant, probably because the bond, though shortened by contraction of the electron shells of the metal, is weakened by interaction with the extra valence shell electrons.
Vibrational Spectrum of 1-Fluoro-1-Chloroethylene
Authors: Mann D. E. , Acquista N. , Plyler Earle K.
Published: April 2005

The infrared spectrum of gaseous FClC: CH2 has been investigated in the range 1.6—52μ. A satisfactory vibrational assignment has been achieved. The planar fundamentals occur at 3069, 3016, 1656, 1383, 1186, 947, 699, 432, and 371 cm—1; the out-of-plane fundamentals are at 836, 607, and 515 cm—1. A table of the thermodynamic functions for the ideal gas is given from 200 to 1500°K.
Iron-Catalyzed Reaction between Nitrosyl Disulfonate and Hydroxylamine Monosulfonate Ions
Authors: Ramsey William J. , Yost Don M.
Published: April 2005

An investigation of the kinetics of the iron-catalyzed reaction between the purple-colored, paramagnetic nitrosyl disulfonate (ON(SO3)2=) ions and hydroxylamine monosulfonate (HONHSO3—) ions has been made. [W. J. Ramsey and D. M. Yost, J. Chem. Phys. 21, 957 (1953)]. At a temperature of 20°C, an ionic strength of 0.026, and total added iron concentrations less than 3.5×10—7 VF, the initial rate of disappearance of ON(SO3)2= is well represented by the equation: −d(ON(SO3)2=)dt=2{k2h1(H+)+k3h1h2(H+)2+h1(H+)+h1h2}(ΣFe+3)(HONHSO3−),where h1 and h2 are the first and second hydrolysis constants for ferric iron and where k2 and k3 are the specific second-order rate constants for the reactions of HONHSO3— with Fe(OH)++ and Fe(OH)2+, respectively. Under the above conditions, and if a value of 3×10—3 is assumed for h1; h2, k2, and k3 have the values, 7×10—4 l·mole—1, 13.7±1.0×104 l·mole—1·min—1, and 1.5±0.5×104 l·mole—1·min—1, respectively.
Pyramidal XY(CH3)2 Molecular Model Classical Vibration Problem
Authors: Beachell Harold C. , Katlafsky Bernard , Lauer James L.
Published: April 2005

Symmetry coordinates are set up from the standpoint of group theory for describing the normal modes of vibration of a valence force pyramidal XY(CH3)2 molecular model in such a way that maximum factorization of the secular determinant is accomplished. The kinetic energy matrix is set up and an analytical expression is given for each matrix element in terms of the reciprocal bond distances, reciprocal masses of the atoms, and the bending and twisting angles. A valence force and a Urey-Bradley field potential is discussed.
Calculation of Depolarization Factors of the Raman Lines of CCl3X Molecules
Authors: Weber Alfons , Ferigle Salvador M.
Published: April 2005

The depolarization factors of the totally symmetric vibrations of CCl3H, CCl3D, and CCl3Br are computed using previously derived expressions for the spur and anisotropy of the polarizability tensor. The associated normal coordinate treatment uses the Wilson FG-matrix technique with a general quadratic potential function. Calculated and observed depolarization factors agree well for stretching but not for the bending modes.
Direct Production of Spectroscopic Specimens from Single Crystals by Controlled Growth from a Vapor
Authors: Zwerdling Solomon , Halford Ralph S.
Published: April 2005

Studies of anisotropic infrared absorption demand quite thin sections of single crystals, having relatively large cross section parallel with one of the few spectroscopically significant planes. This article describes the principles of design, the construction, and the successful operation with benzene of an apparatus for producing such specimens of single crystals. The method involves gradual introduction of vapor into an enclosed space, supporting a gradient of temperature and having the shape desired for the specimen, until self-nucleation occurs in a small vicinity of the colder pole of temperature. Processes of attrition among the nuclei ensue automatically and instantaneously, resulting in the survival of only those that become attached to the confining wall with a most favored orientation, an orientation that can be selected to some degree by factors of design and operation. Thereafter, vapor issuing into the enclosure accretes upon the few surviving nuclei until these seeds coalesce and develop to fill the entire volume available. The method promises to be especially useful for producing and investigating crystals that exist only at low temperatures.
On the Determination of Absolute Intensities from Single- and Multiple-Path Absorption Measurements
Authors: Penner S. S. , Aroeste H.
Published: April 2005

The physical principles involved in conventional absolute intensity measurements are reviewed. Experimental difficulties rule out the use of extrapolation techniques for some spectral transitions. For this reason it is of interest to re-examine the possibility of using total absorption measurements, in conjunction with the curves of growth, for making intensity estimates. Extrapolation methods yield results which are independent of spectral line shape. Use of the curves of growth, on the other hand, implies the assumption that the line contour can be described by combined Doppler and Lorentz broadening.

The curves of growth permit a unique correlation between total absorption and f-value either for spectral lines with pure Doppler broadening or for pure collision broadening. Furthermore, a simple experimental procedure can be devised for estimating both the absolute intensity and the spectral line profile on the basis of single-path and multiple-path absorption measurements. The suggested procedure involves absorption measurements for optical densities (path lengths) under conditions in which the integrated fractional absorption is a relatively sensitive function of spectral line shape. Representative calculations referring to utilization of the proposed method have been carried out for spectral lines belonging to the 2Σ→2II transitions, (0,0)-band, of OH, and also for lines belonging to the fundamental vibration-rotation spectrum of CO.
Diffusion Coefficients of Fatty Acids and Monobasic Phosphoric Acids in n-Decane
Authors: White J. R.
Published: April 2005

Diffusion coefficients of the series of even-numbered fatty acids from C6 to C18, of three dialkyl phosphoric acids, and of 2-ethylhexoic and benzoic acids have been measured in dilute solutions in n-decane at 30°C. Gravity mixed diaphragm cells have been employed in making the measurements. The Stokes-Einstein hydrodynamic relationship adjusted by an empirical coefficient represents the magnitude and variation of diffusion coefficients in the series of fatty acids if corrections are made for solute association and nonsphericity. The unmodified Stokes-Einstein equation predicts diffusion coefficients lower than those measured by approximately a factor of two.
Thermal Diffusion in Polymer Solutions
Authors: Emery A. H. , Drickamer H. G.
Published: April 2005

Thermal diffusion measurements have been made on a series of solutions of polystyrene as follows: (1) Five molecular weights (10 000 to 336 000) in toluene; (2) 136 000 molecular weight in o-xylene, styrene, ethyl benzene, dioxane, and pyridine; (3) Styrene dimer in toluene and styrene; measurements were also made on some binary monomeric mixtures.

The thermodynamic property X∂μ/∂X describes adequately the concentration dependence of the thermal diffusion ratio α. It appears that that portion of the motion of the polystyrene molecule in dilute and somewhat concentrated solutions which is segmental involves 10—13 chain atoms in the moving segment. The results seem consistent with Kauzmann and Eyring's picture for motion of long chain molecules.
Statistical Mechanics of Isotopic Systems with Small Quantum Corrections. I. General Considerations and the Rule of the Geometric Mean
Authors: Bigeleisen Jacob
Published: April 2005

It is shown that the differences in the thermodynamic properties of isotopic molecules subject to small quantum effects (u2/24 law) depend on the difference in the reciprocal masses of the atoms in the molecule and are, therefore, independent of all masses except of those atoms isotopically substituted. This theorem provides a rigorous proof of the rule of the geometric mean for gaseous molecules. It is shown that the partition function ratio for a pair of double-labeled molecules, e.g., N15D3/N15H3 is equal to the ratio for the single-labeled pair N14D3/N14H3. The application of the u2/24 law to isotopic isomer equilibria is pointed out.
Theory of Protein Solutions. II
Authors: Hill Terrell L.
Published: April 2005

The formal theory of the first paper of this series is extended here to include the binding of several different species of ions or molecules on a protein, aggregation in a protein solution, and solutions containing more than one type of protein molecule.
Extended Interpretation of the Boltzmann-Maxwell Equation (A Theory of Nonstationary Random Processes)
Authors: Koga Toyoki
Published: April 2005

Usual theories of statistical mechanics of nonuniform state stand on the assumption of approximately stationary random processes. Generally speaking, this assumption is not reasonable when the state concerned deviates considerably from thermal equilibrium. For a system in such a state, it is difficult not only to define but also to observe a complete set of gross variables. In this case the deviations of the actual future values of the gross variables from their expected future values cannot be neglected.

A new method of coarse-graining is proposed as available to such a state. As a concrete example of system we take a gas. We get a coarse-grained function 〈f〉D by averaging the fine-grained probability function of one molecule over a series of observations made on the system on different occasions where at each observation the system is initially in a common macroscopic state as determined by our incomplete set of initial conditions. It is shown that 〈f〉D satisfies the Boltzmann-Maxwell equation. The equation is valid even when the state concerned deviates considerably from thermal equilibrium and the random processes are not stationary. In this situation, however, the interpretation of the equation is different from the usual one; i.e., the equation predicts not the result of an individual observation of the gas concerned but the result obtained by averaging over a series of observations made repeatedly on different occasions on the same gas under a common incomplete set of macroscopic initial conditions where, with the lapse of time from the start, the result of each observation deviates from the others even in the macroscopic sense. For the time being, the theory is given only in the sense of classical mechanics.
Photolysis of Acetic Anhydride
Authors: Burwasser Herman , Taylor H. Austin
Published: April 2005

The photolysis of acetic anhydride has been studied using a hot mercury arc at temperatures from 60° to 160°C by analysis of the gaseous products. CO and C2H6 are produced at equal rates which are one-half the rate of production of CO2. At 60°C, CO production is delayed initially but in time reaches the same rate as C2H6. Using acetone as actinometer, the quantum yield of CO2 is two, of CO and C2H6, unity. The decomposition of acetic anhydride can be photosensitized by acetone. Mass-spectral analysis of the liquid residue at 160°C showed the absence of acetone, biacetyl, methyl acetate, acetylacetone, and acetonyl acetone. A fragment of mass 57, increasing in intensity with duration of reaction was present in amounts sufficient to account for a material balance. Some steps in the mechanism are discussed.
Electronic Population Analysis on LCAO-MO Molecular Wave Functions. III. Effects of Hybridization on Overlap and Gross AO Populations
Authors: Mulliken R. S.
Published: April 2005

The effects of AO hybridization on gross AO and overlap populations for LCAO-MO electron configurations are discussed in terms of some simple examples, using equations and graphs. The validity of ``gross AO populations'' as true measures of the population in various AOs is critically discussed. It is shown that the degree of hybridization in the AOs of an LCAO MO does not in general give the true amount of s or p character in the MO; this is given instead by the gross s or p population in the MO. Nevertheless, ``forced hybridization'' among the AOs, although not contributing to gross AO populations, leads to important negative contributions to overlap populations, hence to bond energies. For example, forced 2s—2p hybridization has the result that the total overlap population for two pairs of electrons occupying bonding σ LCAO MOs built from 2s and 2pσ AOs in a homopolar diatomic molecule is actually less than the sum of the overlap populations which one would have if one pair could be in an MO built from pure 2s AOs and the other in an MO built from pure 2pσ AOs. This sort of forced hybridization with resultant loss of bond strength may explain why double bonds seldom if ever consist of two σ bonds.
Electronic Population Analysis on LCAO-MO Molecular Wave Functions. IV. Bonding and Antibonding in LCAO and Valence-Bond Theories
Authors: Mulliken R. S.
Published: April 2005

It is shown that there is a practically one-to-one correspondence between the occurrence, on the one hand, of positive (bonding) and negative (antibonding) overlap populations in LCAO theory and, on the other hand, of bonded attractions and nonbonded repulsions in VB (valence-bond) theory. This correspondence is discussed in terms of examples, and is traced for the N2 molecule both for the assumed case of no s–p hybridization, and for the actual case with hybridization. It is pointed out that repulsions between nonbonded atoms in VB theory (including those which give rise to steric hindrance) have their counterpart in negative overlap populations between the same atoms in LCAO theory. The π overlap populations for the various links in 1,3-butadiene are computed by LCAO theory. It is shown how they are affected by conjugation (see Table I) and the results are compared with those of VB theory.
Electronic Spectrum of the Cycloheptatrienyl (Tropylium) Ion
Authors: Murrell J. N. , Longuet-Higgins H. C.
Published: April 2005

The N→V spectrum of the tropylium ion, C7H7+, is studied theoretically by the self-consistent molecular orbital theory. Two transitions are anticipated, an allowed transition at 6.36 ev and a forbidden transition at 4.33 ev. The absorption band at 4.51 ev observed by von Doering and Knox is assigned to the latter transition.
Evaluation of Force Constants from Raman Effect Data. Part 2. Molecules and Radicals of the Planar XY3 Type
Authors: Venkateswarlu K. , Sundaram S.
Published: April 2005

The force constants of 4 molecules and 5 radicals of the planar type XY3 belonging to the point group D3h have been calculated using Raman effect data by the Wilson's F—G matrix method. Applying the empirical rules of Badger and Gordy, the X—Y internuclear distances have been calculated.
Association and the Equation of State
Authors: Ginell Robert
Published: April 2005

A form of the generalized gas law considering explicitly association into all possible species is derived. This law has the additional variables βi, [open phi], and ΣNx. When βi which is a function of the ratio of the surface of the container to the volume is neglected, as it can be at larger volumes, then the equation can be solved. Using the results derived from association theory, this gas law is developed into the form of the virial equation. The virial coefficients are functions of the equilibrium constants of association and the excluded volumes. A method of solution is indicated whereby the equilibrium constants and the excluded volumes of the individual j-mers can be obtained serially.
Interaction of Rotational and Translational Diffusion
Authors: Prager Stephen
Published: April 2005

The Brownian motion of cylindrically symmetric particles is discussed, taking into account the unequal rates of diffusion parallel and perpendicular to the unique axis, as well as rotational diffusion. The problem is solved analytically for the case where the diffusing particles are initially distributed uniformly and with random orientation over a given plane. It is shown that the distribution at a later time is not strictly Gaussian, as is the case with spherically symmetric particles. On a macroscopic scale the effect is a small one.
Reactions of Br80 (18 min) Produced by Isomeric Transition of Br80m (4.58 hr) with Benzene and Methylated Benzenes
Authors: Carlson T. A. , Koski W. S.
Published: April 2005

The reactions of benzene, toluene, para- and ortho-xylene, and mesitylene with Br80 as a result of isomeric transition have been studied. It was found that the reactions were complex. The substitution reaction was accompanied by condensation reactions. Evidence was found that organic bromides with boiling points higher than bromobenzene were formed in appreciable yields. Hydrolysis experiments indicated that both primary and secondary bromides were included in these high boiling compounds. Scavenger experiments indicated that the substitution reactions were proceeding in the main through fast bromine atom reactions. No evidence was obtained that any appreciable amounts of the substitution reactions were proceeding through a positive bromine ion mechanism.
On the Optical Properties of Solids
Authors: Rosenstock Herbert B.
Published: April 2005

A consistent treatment of the usual linear theory of lattice vibrations in ionic crystals without the use of the symplifying cyclic boundary conditions is shown to lead to an electric moment associated with each normal frequency which, like the frequency itself, is a quasicontinuous function of the propagation vector. As a result, a broadening of the line spectrum of elementary theory and additional absorption edges of apparently observable magnitude are predicted.
Spectroscopy of Gaseous Carbonyls. I. Infrared Spectra and Thermodynamic Properties of Chromium and Molybdenum Hexacarbonyls
Authors: Hawkins N. J. , Mattraw H. C. , Sabol W. W. , Carpenter D. R.
Published: April 2005

Infrared spectra of gaseous chromium and molybdenum hexacarbonyls were obtained. The spectra could be interpreted as resulting from an X (YZ)6-type molecule of Oh-symmetry. Of the thirteen fundamental vibration frequencies possible, all but three are fairly well established. The fundamentals are shown to be of two distinct types: (1) those which are typical of a heavy outer atom octahedral molecule and (2) those which are typical of the carbon and oxygen moving in opposition to each other. Thermodynamic properties are computed for the ideal gases for various temperatures to 600°K.
Stabilization of Energy-Rich Molecules. I. Energy Transfer with Hydrogen
Authors: Boudart M. , Dubois J. T.
Published: April 2005

The increase in fluorescence yield of β-naphthylamine vapors in the presence of foreign gases provides a new powerful method for studying energy exchange. The effect, discovered by Neporent, is analyzed kinetically and the analog of the Stern-Volmer equation for this effect is derived. Neporent's data are recalculated in the light of this analysis. Fluorescence stabilization by deuterium and sulfur hexafluoride is studied experimentally following the procedure of Neporent. It is concluded, in particular, that the vibrational and rotational modes of the hydrogen molecules are inactive in the excitation or de-excitation of vibrational energy of complex molecules.
Mixtures of Rigid Spherical Molecules
Authors: Alder Berni J.
Published: April 2005

The radial distribution functions for binary mixtures of rigid spheres with a size ratio of 3 to 1 have been calculated at several mole fractions and at several densities by numerical solution of a set of integral equations obtained with the use of the superposition approximation. The distribution functions have then been used to evaluate the relevant thermodynamic properties of the system.
Gaseous Detonations. VI. The Rarefaction Wave
Authors: Kistiakowsky G. B. , Kydd P. H.
Published: April 2005

The density profile of the rarefaction wave which follows a detonation has been determined using the technique of x-ray absorption measurements to follow rapid gas density changes. The observed density-time dependence was found to agree, within experimental errors, with the predictions of the hydrodynamic theory developed by Taylor, Doering, and others. As the theory predicts, the density in the rarefaction wave decreases for approximately one-half of the distance traveled by the detonation wave; behind this is the region of quiescent gas at constant density.
Kinetics of the Thermal Cis-Trans Isomerization of Dideuteroethylene
Authors: Douglas John E. , Rabinovitch B. S. , Looney F. S.
Published: April 2005

The thermal cis-trans isomerization of trans-ethylene, d2 has been studied from 450° to 550°C over a pressure range of 0.9 cm to 31 cm Hg in two quartz reactors. The rate is pressure dependent over the entire pressure range. It is concluded that at 0.9 cm the reaction is a homogeneous, unimolecular reaction. A high pressure activation energy of 65 kcal and frequency factor of 1013 sec—1 are deduced. At higher pressures the reaction is sensitized by processes attendant on polymerization, which occurs as a side reaction with propylene as the principal product. The relation of this study to other work on substituted ethylenes is discussed briefly, as well as a few other topics pertinent to the results obtained.
Infrared Spectrum of Solid n-Octane-1,1,1,8,8,8-d6
Authors: Pimentel George C. , Klemperer William A.
Published: April 2005

The infrared spectrum of n-octane-1,1,1,8,8,8-d6 has been obtained at liquid nitrogen temperature from 1500 cm—1 to 600 cm—1. An assignment of the vibrations into methyl and methylene motions is made.
Paramagnetic Resonance Absorption in Some Cr+3 Complexes
Authors: Singer L. S.
Published: April 2005

The paramagnetic resonance absorptions in several trichelate complexes of Cr+3 have been investigated at room temperature and at 1.2- and 3.0-cm wavelengths. From single crystal measurements on chromic acetylacetonate the orientations of the electric axes were determined and the parameters in the spin-Hamiltonian found to be g = 1.983±0.002, |D| = 0.592±0.002 cm—1, and |E| = 0.052±0.002 cm—1. The asymmetric single absorption peak with g = 4 found in several of the powders and in their liquid solutions is explained on the basis of the relatively large value of D associated with the individual trichelate molecules. The apparent inadequacy of the ``ionic'' model for several chromic compounds is also discussed.
Spherical Interface. II. Molecular Theory
Authors: Buff Frank P.
Published: April 2005

The statistical mechanical theory of plane and spherical interfaces is developed on the basis of the virial theorem and the Gibbsian mechanical and thermodynamic definitions of surface tension. The expressions for the relevant thermodynamic functions in terms of molecular variables are employed in a discussion of the curvature dependence of surface tension which leads to an asymptotic expansion of the grand partition function in terms of the geometrical parameters that characterize the interface and thus provide a criterion for the range of validity of macroscopic concepts.