bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat Capacity, Gas Imperfection, Infrared Spectra, and Internal Rotation Barriers of Ethyl Alcohol
Authors: Barrow Gordon M. 
Published: January 2005

The vapor heat capacities of ethyl alcohol have been measured, as a function of pressure, at 368, 422, and 476°K. From the variation of the heat capacity with pressure, together with vapor densities calculated by the Clapeyron equation, an equation of state for ethyl alcohol has been obtained. This equation has been used to extrapolate the measured heat capacities to the ideal gas state and likewise to correct the observed entropy.
The infrared spectra of vapor C2H5OH, C2H5OD, and liquid C2H5OD are presented and a vibrational assignment is obtained which is sufficiently reliable for the statistical calculation of the thermodynamic properties.
Comparison of the observed and statistically calculated heat capacities and entropies shows that, with a barrier to internal rotation of the CH3 group of 3000 calories, the rotation of the OH group is hindered by a barrier between 0 and 1200 calories. Most satisfactory agreement is obtained for CH3 and OH barriers of 3300 and 800 calories, respectively. Furthermore, comparison of the observed and calculated equilibrium constants for the reaction C2H4(g)+H2O(g)⇌C2H5OH(g)supports the selection of fundamental frequencies and internal rotation barriers.
Crystalline Field in Chrome Alum
Authors: Kleiner W. H. 
Published: January 2005

A calculation is made to test the detailed applicability of the crystalline field approximation for describing magnetic properties of chrome alum.
The theoretical susceptibility formula of Schlapp and Penney represents the experimental susceptibility as a function of temperature reasonably well provided the parameter Dq, which gives a measure of the interaction between the crystalline field and the paramagnetic ion, is arbitrarily chosen to give the best fit. Here Dq is calculated; a model of the surroundings of the Cr+++ ion is used to determine the crystalline field. The calculated Dq is in poor agreement with experimental values, from which it is inferred that the interaction between the Cr+++ ion and its surroundings is so strong that the crystalline field approximation is inadequate to give detailed agreement with experiment. The results are expected to apply to other hydrated paramagnetic salts of the iron group.
Infrared Spectroscopy and the Character of Chemical Binding
Authors: Mecke R. 
Published: January 2005

The importance of the study of the intensities of vibrational bands yielding information concerning the charge distribution in chemical bonds is stressed.
A method is developed for obtaining bond moments in the ground state by the extrapolation of the values calculated for the transition moments of the bond, these being obtained from intensity measurements on the fundamental and overtone bands.
An empirical attempt is made to explain the total moment as the sum of an ionic, a polar, and an inductive component. Agreement between experimental results and the empirical relations is good for OH and CH bonds in a large number of compounds.
The Origin of the Ultrasonic Absorption in Liquids. II
Authors: Herzfeld Karl F. 
Published: January 2005

Excess absorption in nonassociated liquids has been explained by the same mechanism as is responsible for molecular absorption in gases, namely, slow exchange of energy between internal and external degrees of freedom.
In this paper the rate of energy exchange is calculated for benzene and found to be three times too rapid. The Lennard-Jones interaction potential and model of the liquid are used; the fourth-order terms in the interaction provide the coupling between internal vibrations and Debye waves.
Kinetics of Solidification of Supercooled Liquid Mercury Droplets
Authors: Turnbull David 
Published: January 2005

The solidification rate of supercooled liquid mercury droplets is strongly dependent upon the nature of foreign substances on their surface or suspended in them. Droplets (2–8 microns diameter) coated with mercury laurate solidify at rates that are proportional to droplet volume and satisfactorily described by the theory of homogeneous nucleation of crystals. Droplets coated with mercury acetate solidify with frequencies that are proportional to droplet area and in good agreement with the theory of heterogeneous nucleation.
The results on Hg2I2-coated droplets are interpreted on the hypothesis that nucleation is effected by suspended crystallites of one kind. For some droplet dispersions the kinetic results are apparently best described by a multiplicity of solidification frequencies/area or volume. Various hypotheses for this multiplicity are considered.
The Hot Atom Chemistry of the Propyl Bromides; Effect of Phase and Recoil Energy on Retentions
Authors: Fox Maurice S. , Libby W. F. 
Published: January 2005

The yields of the various organic radiobromides formed by neutron irradiation of liquid and solid iso and normal propyl bromides at various temperatures have been determined. Very careful purification of the propyl bromides has given good reproducibility and evidence that the main features of the hot atom chemistry of the propyl bromides have been discovered.
The solidification at the melting point results in a threefold or larger increase in yield of certain products, presumably those formed by epithermal bromine atoms, and a smaller increase for the remainder of the products, such as the mother molecule, presumably formed by hot reactions. Isomerization of isopropyl to n-propyl appears to occur with high probability in epithermal reactions. The epithermal production of bromides of considerably higher boiling point than the mother molecule has been confirmed and the phenomenon discussed theoretically.
Apparently the retentions in the solid phase depend on energy of the recoil bromine, 36-hr Br82 showing 93 percent retention in solid n-propyl vs 80 percent for the 18-min and 4.4-hr Br80's. This is in contrast to the liquid retentions in which no difference has been observed. On this basis it is concluded that the average recoil energy of the 36-hr Br82 is less than those of the two Br80 isomers and that the latter two differ relatively little.
The theoretical implications of the observed product distributions and the phase effect on these distributions and the sensitivity to recoil energy are discussed.
Effect of Polar Solvents on the Absorption Frequency of n→π Electronic Transitions
Authors: McConnell Harden 
Published: January 2005

A variety of spectroscopic data shows that the absorption frequencies of n→π electronic transitions progressively increase in the series of solvents, paraffin, alcohol, and water. This general effect of polar solvents on the frequency of n→π transitions is related to the characteristic change in the molecular charge distribution accompanying this type of transition. In certain cases solvation effects can be of considerable value in distinguishing between n→π and π→π electronic transitions.
Evidence is presented which indicates that the absorption bands of the ions, NO3− (32,000 cm−1), CO3= (46,000 cm−1) and CS3= (20,000 cm−1) are n→π transitions.
Normal Frequencies of a Simple Cubic Lattice. III
Authors: Halford J. O. 
Published: January 2005

For a simple cubic crystal, with forces resisting displacement along and perpendicular to the connecting line between closest neighbors, the secular equation for the internal motions is rigorously broken down to ultimate factors of the form ν2=νx2+α(νy2+νz2),in which νx, etc., are the normal frequencies of the one-dimensional crystal.
The corresponding frequency distribution shows no indication of the ``infinities'' found by Montroll for a model with central forces between first and second neighbors.
The Spectra and Electronic Structure of the Tetrahedral Ions MnO4−, CrO4−−, and ClO4−
Authors: Wolfsberg Max , Helmholz Lindsay 
Published: January 2005

We have made use of a semiempirical treatment to calculate the energies of the molecular orbitals for the ground state and the first few excited states of permanganate, chromate, and perchlorate ions. The calculation of the excitation energies is in agreement with the qualitative features of the observed spectra, i.e., absorption in the far ultraviolet for ClO4−, two strong maxima in the visible or near ultraviolet for MnO4− and CrO4= with the chromate spectrum displaced toward higher energies. An approximate calculation of the relative f-values for the first transitions in CrO4= and MnO4− is also in agreement with experiment.
The data on the absorption spectra of permanganate ion in different crystalline fields is interpreted in terms of the symmetries of the excited states predicted by our calculations.
Mechanism of Bond Rupture in HBr80 Following Isomeric Transition
Authors: Magee John L. , Gurnee E. F. 
Published: January 2005

The work of Hamill and Young (previous paper, this journal) has demonstrated that only a fraction of HBr80(g) and DBr80(g) bonds are ruptured following isomeric transition in Br80. It is known that this transition is completely converted and from the theoretical work of Cooper it is to be expected that all Br80 atoms should be separated from chemical combination. This paper presents a brief theoretical consideration of the rupture mechanism in HBr80 in an attempt to understand why the rupture does not always occur.
Approximate potential energy curves for some of the various molecular ions HBr+z which form during the Auger shower following conversion have been constructed. It is found that there is a very great possibility that these ions all have lowest electronic states which are stable with respect to the dissociation process HBr+Z→H++Br+(Z−1),and the possibility for nonrupturing is thus qualitatively explained for the charging process, since the entire charging time is short compared with molecular collision time in the gas phase. A further necessary condition for nonrupturing (as measured by Hamill and Young) is that the ions can be discharged in collisions without rupture. This process is also considered briefly.
The complete rupture of the C–Br80 bond (in CH3Br80(g)) is also considered and explained qualitatively. In this case no stable molecular states exist for the ions and rupture occurs during the charging process.
Calculation of Some Electronic Energy Levels of Sulfur Hexafluoride
Authors: Duncan A. B. F. 
Published: January 2005

An attempt has been made to calculate the coefficients in LCAO molecular orbital functions of SF6, and ionization and excitation energies of this molecule, using a self-consistent field method. The lowest ionization potential computed is 20.1 ev. Excitation energies to some forbidden and allowed levels are obtained, but are too large to be considered trustworthy. The present treatment was restricted in detail to twelve electrons, six from the sp3d2 valence configuration of sulfur, and six 2pσ of fluorine. The other electrons were treated in smoothed-out core potentials of the sulfur and fluorine atoms. It is believed that unexpectedly large errors may have been introduced by the neglect of detailed interactions of these electrons, and that the molecular orbitals in which they might be put are of importance.
The present calculation is purely theoretical and only the empirical value of the S–F bond distance has been used. All necessary integrals have been evaluated, most of them for the first time, and are collected in tables.
A Detailed Formulation of Kinetic Processes from the Point of View of the Activated Complex
Authors: Benson Sidney W. 
Published: January 2005

By combining Slater's classical treatment for the adiabatic decomposition of an unstable molecule with the Lindemann mechanism for collisional activation it is possible to make a uniform and consistent treatment of kinetic processes of all orders. The high pressure rate constants may then be represented by kobs=α·〈ν̄〉·K#·exp(−E*/kT),where 〈ν̄〉 is a root mean square average of the ``n'' normal modes of vibration of the activated complex, E* is the minimum energy required for reaction, α is a ``transmission coefficient'' which is unity for unimolecular processes and between ½ and 1 for higher order reactions, and K# can be interpreted in terms of an entropy of activation. A more complicated expression is obtained for lower pressures in the case of unimolecular reactions.
The theory is sufficiently detailed to allow predictions on the relation of molecular structure to the pressure region in which collisional activation becomes a limiting rate factor for unimolecular reactions. Similarly predictions may be made concerning the nature of recombination processes and their pressure and temperature dependence. It is shown that recombination processes will have a negative temperature coefficient and in addition the mean life of the activated complex will vary inversely with some power of the strength of the bond being formed. As a result of this, recombination will be more efficient in photochemical or, more generally, low temperature chain reactions than in pyrolytic reactions and consequently chain lengths will be longer in the latter.
Polarization in Electrolytic Solutions. Part II. Measurements
Authors: Jaffé George , Rider John A. 
Published: January 2005

The object of the present investigation was to supply material for testing the theory given in the preceding paper. Therefore, the ``polarization capacitance'' and the ``excess resistance'' of electrolytic solutions were measured over wide ranges of frequency and concentration, and for different plate distances. Also the material of the electrodes was modified, and some temperature coefficients were measured.
After the general introduction (Sec. I) the method used is described in Sec. II; it is essentially a Jones bridge method, with suitable modifications. In Sec. III the cell is described. Section IV deals with the general scope of the measurements and with the procedure in performing them. The range of frequencies was, as a rule, from 18 to 18,000 cps; the molar concentrations varied from 10−4 to 10−2 g-eq/liter. In addition to solutions of KCl and MgSo4, conductance water was investigated. Electrodes of Al, Ni, Au, and Pt were used. In Sec. V a survey of the results, independent of any theory is given. Finally, in Sec. VI the results are compared with those of the theory, by analyzing completely several series of measurements referring to water and KCl solutions. A quantitative agreement can be realized, if (a) the effect of the solvent is taken into account, and if (b) it is admitted that there are, in ``conductance water,'' ions of considerably (about 100 times) lower mobility than the ordinary electrolytic ions. With these assumptions the concentrations and the mobilities of the ions can be determined. Finally, the rate constants which are characteristic of the presented theory can be evaluated.
The Time Dependence of the Potential in Electrode Reactions
Authors: Busing William R. , Kauzmann Walter 
Published: January 2005

Changes in the potential of an electrode with time during electrolysis at constant current are controlled by two factors: (1) the charging and discharging of the double layer capacitor (causing ``capacitive'' changes) and (2) alteration of the composition and other properties of the electrode and the adjacent solution (causing ``non-capacitive'' changes). Equations are derived for the capacitive changes in potential, assuming that the current-voltage relation across the electrode surface is given by Tafel's law.
An experimental study has been made of the potential accompanying the evolution of oxygen from 1N KOH at a platinum anode. When the current was held constant the potential increased slowly with time. When the current was interrupted the potential rapidly decreased, the decay being faster the higher the initial potential. The decay generally followed the above-mentioned equations for a capacitive change in potential, thus making it possible to evaluate effective Tafel constants of the electrode at various stages during electrolysis. These constants were found to depend very much on the time and on the current density, indicating that the electrode surface undergoes important changes. The behavior of the potential on increasing or decreasing the current has also been studied. This too reflects changes in the electrode surface.
Most of these variations can be understood if it is assumed that the electrode surface is non-uniform, the current being carried by relatively few active centers. The non-uniformity is similar to that encountered in ordinary catalysis, but is more complex since the same centers may not be active at all potentials. A simple graphical method of dealing with such a non-uniformity has been developed. It is based on the assumption that Tafel's law is valid for each microscopic element of the surface, and allows the Tafel constants to vary from one element to another. The electrode as a whole may then no longer obey Tafel's law. The concepts of poisoning and promotion, so important in catalysis, are readily incorporated and explain most of the observed results in a direct manner.
On the Calculation of Diffusion Coefficients from Sorption Data
Authors: Hwang Jenn Lin 
Published: January 2005

The general equation of diffusion in which the diffusion coefficient D(c) is given by D0(1+αc+βc2+···), where α, β··· are small, can be solved by the method of successive approximation: The solution has the form c(ξ)=c0(1−Φ(ξ))+c02αψ(ξ)+c03[α2χ1(ξ)+βχ2(ξ)]+···,where Φ(ξ) is the error function and ψ(ξ), χ1(ξ)··· may be computed by numerical integrations. On the other hand, one knows from the sorption experiments the quantities defined by Kc0=2D0½∫0∞ c(ξ)dξ as a function of c0. Thus, by the above solution one may obtain a set of linear equations, from which the constants D0, α, β··· can be found with a reasonable amount of labor.
For practical purposes it would be necessary to tabulate the functions ψ(ξ), χ1(ξ), ···, because they are needed for all the problems of this kind.
Hydrogen Bonding and the Interactions of Water Molecules
Authors: Campbell Edwin S. 
Published: January 2005

A study of proposed explanations for the forces governing the interaction of hydrogen-bonded molecules has been made by investigating various models for the intermolecular potential function for H2O. Implications of the models concerning the known properties of H2O have been examined.
1. After a survey of existing views and data on hydrogen bonding, the electrostatic model is chosen for further study. The criterion selected to winnow the proposed models is their ability to correlate second virial data and the energy of sublimation of ice.
2. The dipolar energy of ice is calculated after Ewald and Kornfeld. Although the dipole approximation fails to pass test No. 1, it is sufficient for interesting observations on some crystal properties of ice.
3. The consistency of the dipole model with Pauling's explanation of the entropy discrepancy is examined.
4. Point charge models are discussed and a multipole calculation made for the ice structure with the highest dipole-dipole energy.
5. Calculations made suggest that a properly chosen point charge model may suffice for the correlation of gas and crystal data.
Semirigorous LCAO—MO—SCF Methods for Three-Dimensional Molecular Calculations Including Electron Repulsion
Authors: Kaufman Joyce J. 
Published: January 2005

A semirigorous LCAO—MO—SCF method including electron repulsion, for three-dimensional closed-shell molecular calculations has been derived. The method starts with the complete many-electron Hamiltonian (in which interelectronic interactions are included explicitly) and the self-consistent molecular orbital equations of Roothaan, then makes a series of systematic approximations for the integrals involved. There are several different levels of approximation which evolve depending on how restrictive one makes the conditions for neglecting a′(1)a″(1), where a′ and a″ are two orbitals on Atom A; and a′(1)b″(1), where a is an orbital on Atom A and b is an orbital on Atom B, A ≠ B, and for neglecting (a′c′′′| G | b″d′v), where a′ is an orbital on Atom A, b″ is an orbital on Atom B, c′′′ is an orbital on Atom C, d′v is an orbital on Atom D, and A, B, C, D are, in general, different atoms. The approximations for the core operators are defined and the core Hamiltonian matrix elements are presented in detail for several of the levels of approximation. The complete expressions for Fa′a′, Fa′a″, and Fa′b″ for closed-shell systems in the two simplest of the approximative schemes are included in the body of this paper. The salient details of the more complicated schemes (corresponding to lesser and lesser neglect of the interaction of charge distributions) are indicated.
These semirigorous LCAO—MO—SCF schemes outlined in this paper hold promise for less-than-rigorous yet better-than-empirical calculations for the whole gamut of three-dimensional molecules from simple inorganics through complicated organics. An analogous treatment with the same approximations for the neglect of certain integrals can also be applied to an open-shell LCAO—MO—SCF procedure.
Condensed-Phase Photolysis and Radiolysis of 2-Methylbutane
Authors: Scala A. A. , Ausloos P. 
Published: January 2005

The condensed-phase photolysis of i-C5H12–i-C5D12 mixtures, and CH3CD (CH3) CH2CH3 has been investigated at photon energies above and below the ionization energy of 2-methylbutane (10.32 eV), that is, at 1470 Å (8.4 eV), 1236 Å (10.0 eV), and 1048–1067 Å (11.6–11.8 eV). The electronically excited 2-methylbutane molecule undergoes essentially the same primary decomposition processes in the condensed phase as in the gas phase. However, in contrast with the gas phase, the internally excited fragments formed in these primary processes are entirely deactivated.
It is demonstrated that C5H12+ ions are produced at 1048–1067 Å and to a lesser extent at 1236 Å. A fraction of these ions transfer an H2 molecule to c-C3D6 to form CD2HCD2CD2H as a product. In the krypton and argon sensitized radiolysis at 77° and 20°K, respectively, energy transfer from the rare-gas matrix to 2-methylbutane occurs with high efficiency and all products can be accounted for by decomposition of neutral excited 2-methylbutane, formed by excitation transfer and/or neutralization of ions formed in charge-transfer reactions with rare gas ions.
In the radiolysis of pure 2-methylbutane at 77°K, ethane and propane are almost entirely formed through molecular elimination and geminate radical disproportionation processes. Addition of an electron scavenger such as CCl4 lowers the yields of these products, as well as those of the corresponding olefins (e.g., C3H6 and C2H4). A change in the neutralization mechanism of the parent ion (C5H12+) can account for the latter observation. Apparently, fragmentation of the parent ion is unimportant in the condensed phase. Butane (G∼0.1) is the only product which can tentatively be related to reaction of fragment ions (C4H8+, C4H9+). The modes of formation of products, such as the pentenes and the hydrogen in the radiolysis of pure C5H12 remain unexplained.