bluuebunny/crossref_metadata_2025 huggingface dataset:
Accommodation Coefficients for Heat Conduction Between Gas and Bright Platinum, for Nine Gases Between 80°K (or Their Boiling Points) and 380°K
Authors: Grilly Edward R. , Taylor William J. , Johnston Herrick L.
Published: January 2005

Accommodation coefficients toward bright platinum for air, oxygen, nitric oxide, carbon monoxide, carbon dioxide, nitrous oxide, methane, hydrogen, and helium are computed from the (1/Ka) versus (1/P) slopes of the thermal conductivity measurements of Taylor and Johnston and of Johnston and Grilly. The results—which cover the temperature range 80°K to 380°K—are tabulated for the several gases, and are collected in a graph where comparison with results obtained by other investigators are also included. Our results with hydrogen rise toward a coefficient of unity with lowering temperature, in confirmation of measurements by others, but those for other gases drop steeply at temperatures between room temperature and that of liquid air. Our data are in generally good agreement with the recent accurate work of Amdur, Jones, and Pearlman, at room temperature. The accommodation coefficients which are derived from the reciprocal K versus reciprocal P plots differ slightly from Knudsen accommodation coefficients, and are referred to as ``Maxwell-Knudsen'' coefficients. Equations are derived which give the relationship between the reciprocal slopes, the temperature jump constants g′, and the M-K accommodation coefficients.
The Determination of Critical Concentrations for the Formation of Soap Micelles by the Spectral Behavior of Pinacyanol Chloride
Authors: Corrin M. L. , Klevens H. B. , Harkins William D.
Published: January 2005

The absorption spectrum of pinacyanol chloride in aqueous solutions of anionic soaps changes sharply to that characteristic of its solutions in organic solvents over a short range of soap concentration. This effect is attributed to the formation of micelles, in whose hydrocarbon-like layers or cores the dye is solubilized. The concentration of soap at which this spectral change occurs is taken as ``the critical concentration for the formation of micelles.'' In water the dye exhibits an absorption band at 5500A which disappears rapidly as the concentration of molecular soap increases. Thus, even 0.00006 molar potassium laurate gives a large effect. At about 0.0126 M the γ-band at about 4800A reaches a high intensity, which falls, with further increase of concentration, very rapidly close to the critical concentration. At 2.3 to 2.4×10−2 for potassium laurate and 6×10−3 for the myristate the α-band (ca. 6150A) and the β-band (ca. 5700A) begin to increase rapidly in intensity and these are considered as the critical concentrations, since these are the prominent bands in the solution of the dye in an oil. Alkali oleate and dilinoleate soaps exhibit an additional band (ω-band) at about 5200A. Some other critical concentrations determined by this method are 3.6–5.2×10−4 molar for sodium cetyl sulfate, 2.5–3.2×10−2 molar for potassium dehydroabietate, 7–12×10−4 molar for potassium oleate, and 2.5×10−4 molar for potassium dilinoleate. The values for the last two soaps are uncertain, since their behavior differs considerably from that displayed by the salts of saturated acids. All measurements were made at 25.8°C with the exception of the sodium cetyl sulfate which was investigated at 35.8°C. An absorption band at approximately 4800A appears in all the soap solutions measured below the critical concentration with the exception of potassium dilinoleate. This band is absent when salts or bases are added to the dye solution. A titrametric method has been developed for the determination of critical concentrations of soaps in the presence of added salts and hydrocarbons.
The Crystal Structure of Synthetic Boehmite
Authors: Reichertz Paul P. , Yost W. Jacque
Published: January 2005

Crystal structure computations have been made for synthetic boehmite, the α-modification of aluminum oxide monohydrate, using the powder method. The experimental data were found to fit an orthorhombic lattice with constants a0 = 2.859A, b0 = 12.24A, and c0 = 3.691A. The assignment of four AlO (OH) groups to this unit cell gives a calculated density of 3.063 g/cc. The observed density is 2.977 g/cc. The general space group extinctions were found to agree with those of D2h17. Generalized atomic coordinates were roughly determined by application of Pauling's coordination theory for ionic crystals and the determinations refined by the usual intensity computations. The parameter values selected were uAl = −0.334, uOI = 0.287, uOII = 0.067. It is suggested that the inconsistencies which exist between the experimental and computed intensity data may be explained by the occurrence of a small quantity of γ—Al2O3 in the synthetic samples used. The value of 2.47±0.07A obtained for the hydrogen bridge distance is discussed. This value is less than that observed for any previously determined structure.
Corresponding States in the Frozen Rare Gases
Authors: Murphy G. W. , Rice O. K.
Published: January 2005

A method is presented for extending the principle of corresponding states to solids at comparatively low temperatures, where quantum effects are appreciable. The method has been applied to solid neon, argon, krypton, and xenon. The principle of corresponding states, as applied to the liquid and vapor states, is used for calculation of the potential energies and interatomic distances of three of the substances in terms of the other. The quantum contribution to the energy is taken into account by assuming the Debye theory for all the solids, and this is related to the potential energy by means of a modified Grüneisen equation. The Debye θ's for three of the solids are determined from that of the other by a dimensional analysis of the mechanical system. Using this information, Cp for neon, argon, and krypton have been calculated from the experimental data for xenon. Agreement of the calculated values with experiment is reasonably good; small deviations may be caused by breakdown of the Debye theory, or may be indications of inexactitude in the law of corresponding states.
On the Ultraviolet Absorption Spectrum of Ozone
Authors: Eberhardt W. H. , Shand W.
Published: January 2005

The absorption spectrum of ozone has been investigated in the near ultraviolet from λ3439 to 3850A at two temperatures. The bands observed have been interpreted as arising in part from transitions from the vibrationless ground electronic state and in part from transitions from excited vibrational levels of the ground electronic state. The distinction between the two groups is based primarily on the relatively large temperature sensitivity of the intensity of the bands ascribed to transitions from excited vibrational states. A partial analysis gives strong support to the assignment of the frequency 1043 cm−1 to a fundamental vibration of the molecule. Moreover, it appears quite unlikely that the frequency 710 cm−1 can be eliminated as one of the fundamental frequencies. No information concerning the third fundamental frequency was obtained.
The Site of Reaction in Direct Photographic Development
Authors: James T. H.
Published: January 2005

The rate of the silver-catalyzed reduction of silver ions derived from soluble silver salts is directly proportional to the concentration of the hydroquinone when the latter is the reducing agent. The kinetics thus give no evidence that adsorption of hydroquinone by silver is a pre-requisite for reaction. Similar results are obtained with catechol as reducing agent. The rate of development of silver bromide grains, on the other hand, varies approximately with the 0.6 power of the hydroquinone concentration (pH 8.0–8.9) and the 0.56 power of the catechol concentration (pH 7.7), indicating adsorption by the silver bromide or by the silver-silver bromide interface region prior to reaction. This result is in contradiction with the ``electrode'' mechanism of development, but is in accord with the concept of a direct reaction between the developing agent and silver halide at the triple interface.
The Mercury-Sensitized Reaction between Hydrogen and Nitrous Oxide
Authors: Taylor H. Austin , Zwiebel Norman
Published: January 2005

The mercury photo-sensitized reaction of nitrous oxide and hydrogen to produce nitrogen and water has been studied in the pressure range 10–500 mm. It is shown that hydrogen exerts only a minor influence on the rate. A mechanism has been postulated involving a sensitized decomposition of nitrous oxide into nitrogen and atomic oxygen at a rate roughly one thousand times the rate of reaction of hydrogen atoms with nitrous oxide. The atomic oxygen promotes chains by reaction with hydrogen, the chains are terminated by recombination of hydrogen atoms, on the wall at low pressure and mainly in the gas phase above 100 mm pressure under the experimental conditions.
The Mercury Photo-Sensitized Reactions of Isobutene
Authors: Gunning H. E. , Steacie E. W. R.
Published: January 2005

An investigation has been made of the reaction of isobutene with mercury (3P1) atoms at 30°C. The main products of the reaction are propylene, liquid polymer, and acetylene. Smaller amounts of a large number of other products are also formed. The over-all rate of consumption of isobutene, as well as the rates of formation of propylene, acetylene, and propane are independent of pressure in the region of complete quenching. Furthermore the rate of formation of propylene is just double the rate of formation of acetylene. The maximum quantum yield of consumption of isobutene is 0.59. The principal steps in the mechanism proposed for the reaction are i−C4H8+Hg(3(P1)→C4H7+H+Hg(1S0),H+i−C4H8→C4H9,C4H7+i−C4H8→C2H2+C6H13,C4H9+i−C4H8→C3H6+C5H11,C5H11+i−C4H8→C3H6+C6H13.On the above mechanism the initial step would be only about 16 percent efficient. Polymerization is considered to be initiated mainly by the C6H13 radical. The average molecular weight of the polymer would then be approximately 240.
Electron Diffraction Investigation of the Molecular Structure of Thioacetic Acid
Authors: Gordy Walter
Published: January 2005

The structure of thioacetic acid has been investigated by the method of electron diffraction. The molecule was found to have very little resonance interaction between bonds. The interatomic distances found are: C=O=1.24±0.04A; C–S=1.78±0.02A; C–C=1.54±0.06A. The angle CCO was found to be 125°±5° and angle CCS, 110°±5°. The distances assumed are: C–H=1.09A and S–H=1.34A. Angle OCS was assumed to be 125°.
Complex Orthogonal and Antiorthogonal Representation of Lorentz Group
Authors: Kursunoğlu Behram
Published: January 2005

By using the fact that a plane electromagnetic wave is described by two Lorentz invariant statements, a complex orthogonal representation of the Lorentz group, including charged fields, is discussed. The representation provides the possibility of a combined study of the P, C, T symmetry operations for spin ½ and spin 1 fields. In particular, the chargelessness of the neutrino as a complex fermion field results from a reducible three charge states representation of the complex group.
A Criterion for the Free Character of Fields
Authors: Lopuszanski Jan
Published: January 2005

It is shown that a field is a free field as soon as the states generated by the Heisenberg field and the incoming field operators operating on the vacuum coincide [statement (i)]. Several conclusions are drawn from statement (i) concerning the strong convergence of the field for t tending to infinity [statement (ii)], the uselessness of the local clothed particle representation [statement (iii)], and the diagonalization of the Hamiltonian [statement (iv)], as well as the time behavior of the mathematical vacuum [statement (v)].
Approximate Stress Energy Tensor for Gravitational Fields
Authors: Taub A. H.
Published: January 2005

An invariant formulation in Minkowski space-time of an approximation to the Einstein theory of gravitation is given. In this formulation a tensor is introduced which may be interpreted as the approximate stress energy tensor of the gravitational field. Conservation laws involving this tensor and the material stress energy tensor are formulated. The behavior of these tensors under ``gauge transformations'' of the weak gravitational fields is discussed. The classical limit of the conservation of energy equation is studied and the results are compared to some observations of Bondi on a possible analog of the Poynting vector for a gravitational field.
Principles of Limiting Absorption and Limiting Amplitude in Scattering Theory. II. The Wave Equation in an Inhomogeneous Medium
Authors: Odeh Farouk M.
Published: January 2005

This is a continuation of Part I with special emphasis on wave equations in an inhomogeneous medium.
Asymptotic Expansion of the Bardeen-Cooper-Schrieffer Partition Function by Means of the Functional Method
Authors: Mühlschlegel B.
Published: January 2005

The canonical operator exp [−β(H − μN)] associated with the Bardeen-Cooper-Schrieffer (BCS) model Hamiltonian of superconductivity is represented as a functional integral by the use of Feynman's ordering parameter. General properties of the partition function in this representation are discussed. Taking the inverse volume of the system as an expansion parameter, it is possible to calculate the thermodynamic potential including terms independent of the volume. This yields a new proof that the BCS variational value is asymptotically exact. The behavior of the canonical operator for large volume is described and related to the state of free quasiparticles. A study of the terms of the thermodynamic potential which are of smaller order in the volume in the low-temperature limit, shows that the ground state energy is nondegenerate and belongs to a number eigenstate.
Transient Response of a Dipole Antenna
Authors: Morgan Samuel P.
Published: January 2005

The transient current in a long dipole antenna excited by a step-function voltage across an infinitesimal center gap has recently been calculated by Wu. A simpler derivation of Wu's result is given using double Fourier transformation.
Spectrum of the Scattering Integral Operator in the Physical Energy Sheet
Authors: Meetz K.
Published: January 2005

The kernel of the integral equation for the nonrelativistic scattering of a spinless particle by a potential —λV can easily be symmetrized, if V has a definite sign. Under suitable conditions for the potential the symmetrized kernel is square integrable and generates a completely continuous transformation of the space L2 that has a pure point spectrum.

The scattering kernel is a two-valued function of the energy s. For negative real values of s in the first Riemann sheet it is symmetric (Hermitian) and can be spectral decomposed in the usual way. Eigenvalues and eigenelements can be analytically continued, at least into the first s sheet and even into the finite second s sheet, if the potential decreases faster than any exponential function for r → ∞. Eigenelements at two complex conjugate points s, s* form a complete biorthogonal system of L2. The original and the resolvent kernel can be expressed in terms of that system and the eigenvalues, for s in the first and eventually finite second sheet.

If the potential is indefinite, the scattering kernel is of polar type for negative real s and can be represented in terms of polar eigenvalues and eigenelements. These may be continued in the same way as for a definite potential.

The distribution of eigenvalues in the λ plane is studied for arbitrary complex s and related to the occurrence of bound states and resonances. It is shown that Born expansions for resolvent quantities do converge, if and only if neither λV nor —λV create bound states.
Proof of a Conjecture by Dyson in the Statistical Theory of Energy Levels
Authors: Gunson J.
Published: January 2005

A conjectured identity relating the statistical properties of two types of ensembles occurring in a statistical theory of the distribution of energy levels in nuclei and other complex systems is proved.
Proof that the Two-Dimensional Shape of Minimum Surface Free Energy is Convex
Authors: Mullins William W.
Published: January 2005

Published proofs that the Wulff construction yields the shape of minimum surface free-energy for a crystal of fixed volume (or area in the two-dimensional case) are all based on the tacit but unproven assumption that the equilibrium shape is convex. In the present work, this assumption is justified for the two-dimensional case by establishing from a special sequence of constructions that corresponding to every nonconvex curve of line (surface) energy E, there is a convex curve enclosing the same area but having a line energy less than E. Therefore the two-dimensional equilibrium form must be convex and the existing proofs of the Wulff construction in two dimensions are vindicated; unfortunately the method of proof cannot be extended to three dimensions.
The Baker-Hausdorff Formula and a Problem in Crystal Physics
Authors: Weiss G. H. , Maradudin A. A.
Published: January 2005

A derivation is given of the Baker-Hausdorff formula for z = ln exey where x and y are noncommuting operators. This result is then used to obtain an expression for z in the case that X = P2 + Q2 and y = αP + βQ, where P and Q are two operators whose commutator [P,Q] = c is a c number. With the aid of this result a very simple derivation of the expression for the intensity of x rays scattered by the thermal vibrations of a crystal is presented.
Thermodynamic Functions of a Fermi System of Dilute Hard Spheres at Temperatures Near Absolute Zero
Authors: Yang Chen-Ping
Published: January 2005

The thermodynamic functions of a Fermi system of hard spheres at temperatures near absolute zero are calculated through the evaluation of the coefficient appearing before the second-order term a2, in the fugacity series for the system where a is the hard sphere diameter.
Asymptotic Theory of Hamiltonian and other Systems with all Solutions Nearly Periodic
Authors: Kruskal Martin
Published: January 2005

Consider a system of N ordinary first-order differential equations in N dependent variables, and let the independent variable s not appear explicitly. Let the system depend on a small parameter ε and possess a formal infinite power series expansion in ε, and suppose that the limiting system for ε = 0 exists and has only periodic solutions. Then a formal solution can be constructed involving infinite power series in ε and satisfying the equations over large domains of s (of order 1/ε). The true solutions of the system exist over such domains and are asymptotically represented as ε→0 by the formal solutions. The construction is based on the standard type of formal series solution of a ``reduced'' system of N − 1 equations in N − 1 dependent variables and with the new independent variable σ = ε s; the omitted variable is essentially an angle variable φ describing the phase around the simple, closed curves. If the original system is Hamiltonian, then one can define the usual action integral J = ∫ p·dq to all orders; the integral is taken around the phase ring. It is proved that J is an integral of the system and that the Poisson bracket of φ with J is unity, both to all orders. The usefulness of this particular integral is that it is computable locally. The reduced system, after elimination of another dependent variable by means of the constancy of J, can itself be put in Hamiltonian form; if its solutions are nearly periodic, the whole procedure can be reapplied. The present theory encompasses previous proofs of adiabatic invariance to all orders for particular systems such as the harmonic oscillator, the nonlinear oscillator, the charged particle gyrating tightly in a given electromagnetic field, and the longitudinal back-and-forth motion of such a particle trapped between two ``magnetic mirrors'' in a weak electric field. There are many other applications.
Empty Space Metrics Containing Hypersurface Orthogonal Geodesic Rays
Authors: Newman Ezra T. , Tamburino Louis A.
Published: January 2005

In this paper we obtain all empty space metrics which possess hypersurface orthogonal geodesic rays with nonvanishing shear and divergence. By straightforward integration of the Newman-Penrose equations, which are equivalent to the Einstein equations, all solutions are found in closed form and are unique up to a few arbitrary constants. The method of integration is illustrated in detail for the Robinson-Trautman solutions.
On the Characteristic Initial Value Problem in Gravitational Theory
Authors: Sachs R. K.
Published: January 2005

The problem of determining a solution of the Einstein field equations for the gravitational field from data set on a pair of intersecting characteristic (that is, null) hypersurfaces and on their intersection Σ is considered. It is shown that by giving the conformal inner metric of each hypersurface, the inner geometry of Σ, the two mean extrinsic curvatures of Σ, and one additional extrinsic quantity for Σ, one completely determines a solution in a space-time region. In a suitable coordinate system giving the above data amounts to giving four functions of three variables, four functions of two variables, and one function of one variable; all these can be given without any constraints. In a given space time with given Σ the functions are almost, but not entirely, known functions of their arguments. All the derivations and discussions are applicable only in a sufficiently small four-dimensional region.
Studies in Perturbation Theory. IV. Solution of Eigenvalue Problem by Projection Operator Formalism
Authors: Löwdin Per-Olov
Published: January 2005

The partitioning technique for solving secular equations is briefly reviewed. It is then reformulated in terms of an operator language in order to permit a discussion of the various methods of solving the Schrödinger equation. The total space is divided into two parts by means of a self-adjoint projection operator O. Introducing the symbolic inverse T = (1—O)/(E—H), one can show that there exists an operator Ω = O + THO, which is an indempotent eigenoperator to H and satisfies the relations HΩ = EΩ and Ω2 = Ω. This operator is not normal but has a form which directly corresponds to infinite-order perturbation theory. Both the Brillouin- and Schrödinger-type formulas may be derived by power series expansion of T, even if other forms are perhaps more natural. The concept of the reaction operator is discussed, and upper and lower bounds for the true eigenvalues are finally derived.
Propagator Ghosts and Regge Poles
Authors: Fried H. M. , Taylor J. G.
Published: January 2005

In the approximation of considering only vertex contributions to the propagator, we determine sufficient conditions on the two-particle scattering amplitude which does not generate ghosts in the propagator. The Regge type of behavior does not satisfy these conditions, and will give rise to ghosts unless cancellations occur coming from the higher inelastic contributions to the vertex-function unitarity condition, which have been neglected in our calculation. The double-pole behavior discussed by Frye is found to be the only two-particle scattering-amplitude behavior which will have no propagator ghosts, under certain general conditions.
Fermi Normal Coordinates and Some Basic Concepts in Differential Geometry
Authors: Manasse F. K. , Misner C. W.
Published: January 2005

Fermi coordinates, where the metric is rectangular and has vanishing first derivatives at each point of a curve, are constructed in a particular way about a geodesic. This determines an expansion of the metric in powers of proper distance normal to the geodesic, of which the second-order terms are explicitly computed here in terms of the curvature tensor at the corresponding point on the base geodesic. These terms determine the lowest-order effects of a gravitational field which can be measured locally by a freely falling observer. An example is provided in the Schwarzschild metric. This discussion of Fermi Normal Coordinate provides numerous examples of the use of the modern, coordinate-free concept of a vector and of computations which are simplified by introducing a vector instead of its components. The ideas of contravariant vector and Lie Bracket, as well as the equation of geodesic deviation, are reviewed before being applied.
Galilei Group and Nonrelativistic Quantum Mechanics
Authors: Levy-Leblond Jean-Marc
Published: January 2005

This paper is devoted to the study of the Galilei group and its representations. The Galilei group presents a certain number of essential differences with respect to the Poincaré group. As Bargmann showed, its physical representations, here explicitly constructed, are not true representations but only up-to-a-factor ones. Consequently, in nonrelativistic quantum mechanics, the mass has a very special role, and in fact, gives rise to a superselection rule which prevents the existence of unstable particles. The internal energy of a nonrelativistic system is known to be an arbitrary parameter; this is shown to come also from Galilean invariance, because of a nontrivial concept of equivalence between physical representations. On the contrary, the behavior of an elementary system with respect to rotations, is very similar to the relativistic case. We show here, in particular, how the number of polarization states reduces to two for the zero-mass case (though in fact there are no physical zero-mass systems in nonrelativistic mechanics). Finally, we study the two-particle system, where the orbital angular momenta quite naturally introduce themselves through the decomposition of the tensor product of two physical representations.
Generalized Dielectric Function for Classical Many-Body Systems
Authors: Ron Amiram
Published: January 2005

A dielectric function is introduced for classical systems of many interacting particles in terms of the N-particle distribution function in phase space. The system is considered as a whole using the Liouville equation instead of the canonical equations or the B–B–G–K–Y hierarchy. To facilitate the calculation, the diagrammatic technique of Prigogine and Balescu is introduced in terms of which a systematic asymptotic analysis is carried out for two simple cases: (1) a system of weak interaction and (2) a simple model of plasma. The treatment is restricted to systems in thermal equilibrium.
Statistical Behavior of Linear Systems with Randomly Varying Parameters
Authors: Leibowitz M. A.
Published: January 2005

We consider an nth-order system of ordinary linear differential equations whose coefficients are random functions of the time. In particular, we discuss the case where each of these coefficients is a random noise. A differential equation for the probability distribution of the solutions of the random D. E. is derived and from this the moments can be calculated. Special attention is given to the case of Gaussian noise but the treatment is applicable to any type of noise. Finally, various conditions for stability are discussed.
Dielectric Behavior of Nonrigid Molecules. I. The Simultaneous Relaxation Mechanisms of Diphenyl Ethers and Analogous Compounds
Authors: Fong Francis K.
Published: January 2005

Possible relaxation mechanisms for the anomalously rapid relaxation process in diphenyl ether and related compounds are critically examined and compared with recent experimental results. It is concluded that mechanisms involving inversion and atomic dipole are unlikely, and that shifts of electronic charge and consequent change in direction of the π-electron or mesomeric moment accompanying rotation of the rings around their bond to the rest of the molecule do not play such an important role in molecules of the diphenyl ether type as to account for the lowering of the relaxation times of these molecules. It is proposed that short coupled rotations of the rings around their bonds to the central atoms or of the C6H5X group and the other ring can change the direction of the molecular dipole moment in these molecules with much less effect upon the surrounding molecules than would be exerted by over-all molecular rotation without internal motion. A theory is described whereby such mechanisms, which give relaxation times shorter than those associated with rotation of a rigid molecule, occurring simultaneously with the over-all molecular orientation, are responsible for the observed shortening of relaxation time and must predominate over any effect of possible mesomeric moment.
Energy Transfer in Charge-Transfer Complexes. III. Intersystem Crossing
Authors: Christodouleas N. , McGlynn S. P.
Published: January 2005

The quantum yield ratio of phosphorescence to fluorescence, φp/φf, of the donor component has been investigated for charge-transfer complexes of naphthalene, phenanthrene, and acenaphthene with the acceptors sym-trinitrobenzene, 2,4,7-trinitrofluorenone, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, and tetra-iodophthalic anhydride. It is shown that φp/φf increases for fixed donor concentration as the concentration of the acceptor increases, and that the value of φp/φfΞy″ of the complexed emitter may be deduced from the observed rate of increase of φp/φf. By this means it is shown that complexing with sym-trinitrobenzene increases the quantum yield ratios of naphthalene and acenaphthene by factors of approximately 30 and 75, respectively. An increase of approximately 103 is observed upon complexation with the tetrahalophthalic anhydrides, and a heavy-atom effect is distinctly manifested within the anhydride series. It is possible to bracket values of the intersystem rate constant, ki, whence it is shown that in charge-transfer complexes the increase in the intersystem crossing probability makes it an important fluorescence quenching mode. It is also shown that the intersystem crossing process is significantly more sensitive to complexation and heavy-atom effects than the phosphorescence emission or quenching processes. The observed effects are briefly discussed in terms of conventional theories.

Charge-transfer fluorescence of some crystalline complexes at room temperature is described, and the mirror-image relationship to the charge-transfer absorption shown by Czekalla et al. is verified. Finally, some thermodynamic data for the investigated complexes are presented, and from the behavior of extinction coefficient and stability of the complexes as a function of λmax of the charge-transfer bands it is inferred that the charge-transfer band borrows much of its intensity from transitions proper to the donor.
Electron Spin Resonance in Anhydrous Copper Nitrate
Authors: Owen S. J. T. , Standley K. J. , Walker A.
Published: January 2005

The electron spin resonance spectra of solutions of anhydrous copper nitrate in ethyl acetate, methyl cyanide, nitromethane, and dioxan have been measured at 9.2 kMc/sec and 77°K. In ethyl acetate, the hyperfine structure was sufficiently resolved to permit analysis in terms of a Hamiltonian representing tetragonal symmetry. The data were g∥=2.34, g⊥=2.07, A=0.0121 cm—1, B=0.0040 cm—1. Almost pure σ-bonding between the copper ion and the solvent ligands is indicated. No hfs was visible in other frozen solutions. For nitromethane gpeak=2.15 and evidence is presented to suggest that the copper complex in this case is nearly cubic.
Ultrasonic Dispersion Observed by Optical Diffraction. I. Nitrous Oxide
Authors: Martinez J. V. , Strauch J. G. , Decius J. C.
Published: January 2005

Ultrasonic wavelengths in gases can be measured with a precision of about 1 in 103 by photographing the diffraction due to the traveling ultrasonic waves acting as a grating. The fundamental problems involved in the optical technique are discussed. An apparatus utilizing an objective lens of focal length 1.5 m and of aperture f/20 was constructed, and employed at an ultrasonic frequency close to one megacycle sec—1 to photograph the first order diffraction of the Hg 5461 Å line due to argon and nitrous oxide at pressures ranging from ¼ to 10 atm with exposures between 0.02 and 60 sec.

Using argon as a nondispersive gas for a standard, the ultrasonic velocities were calculated for N2O; a well-defined dispersion curve for N2O was obtained, from which a relaxation time at one atmosphere and 300°K of τ=0.99 μsec. was obtained, in excellent agreement with the results of other workers who have employed ultrasonic absorption or interferometry.

The use of an optical system of the type employed in the Lyot Coronagraph is discussed as a means of increasing the utility of the optical method.
Linewidths in the 2–0 Band of Carbon Monoxide Broadened by Nitrogen and Hydrogen
Authors: James Thomas C. , Plyler Earle K.
Published: January 2005

Linewidths in the 2–0 band of carbon monoxide, pressure broadened by nitrogen and hydrogen, have been measured up to | m | = 20. The widths are of the same order of magnitude in both cases, ranging from 0.074 to 0.052 cm—1/atm for nitrogen broadening, and ranging from 0.068 to 0.063 cm—1/atm for hydrogen broadening. The measurements were made at 295°K.
Nature of the Two-Electron Chemical Bond. IV. Natural Orbitals for He2++
Authors: Shull Harrison , Prosser Franklin
Published: January 2005

Natural orbital expansion coefficients are presented for the function calculated by Fraga and Ransil. It is concluded that the relative minimum and maximum in the energy as a function of distance is not accompanied by significant alterations in bonding character other than those to be expected by normal distance variation. The perturbation of He++He+ by He+He++ is therefore small.
Heats of Mixing in Binary-Liquid—Alkali-Metal Mixtures
Authors: Yokokawa T. , Kleppa O. J.
Published: January 2005

The enthalpies of mixing in all the binary-liquid alloys formed among the alkali metals sodium, potassium, rubidium, and cesium have been measured by reaction calorimetry at 111°±2°C. All systems except rubidium—cesium show positive enthalpies of mixing. There is a tendency for the mixing enthalpies to become more positive and also more unsymmetrical as the two metals become more separated in the periodic table.

A comparison of the new enthalpy data with reported phase-diagram information indicates that the three liquid alloys which contain sodium all exhibit nearly ideal entropies of mixing. For potassium—rubidium, potassium—cesium, and rubidium—cesium, the new heat data, combined with the available phase diagrams, permit estimates to be made of the excess free energies of mixing in the solid solutions.
Luminescence of Europium Hexafluoroacetylacetonate
Authors: Halverson F. , Brinen J. S. , Leto J. R.
Published: January 2005

The luminescence spectrum of europium tris-hexafluoroacetylacetonate in various solutions is presented. While the presence of moisture has a marked effect on the spectral appearance of luminescence near 6100 Å, it does not appear to influence the long-lived phosphorescence near 4500 Å. The presence of this blue phosphorescence poses some questions regarding the rates of various energy-transfer processes.
Vibrational Energy Exchange in Quantum and Classical Mechanics
Authors: Rapp Donald
Published: January 2005

The probability of vibrational energy exchange in a molecular collision can be calculated using (1) a wave-mechanical treatment using the method of ``distorted waves,'' (2) a semiclassical time-dependent perturbation procedure in which the perturbation energy is obtained as a function of time from the classical collision trajectory, and (3) a purely classical calculation of the energy transferred to a classical vibrator. These methods are reviewed, related, and compared.
Natural Expansion of the First-Order Density Matrix for a Spin-Projected Single Determinant
Authors: Harriman John E.
Published: January 2005

The first-order density matrix is obtained for the state corresponding to a spin projection of a general different orbitals for different spins single determinental function. Explicit expressions are given for the natural orbitals and occupation numbers in terms of parameters characteristic of the unprojected state. The spin density and the charge density matrices are found to have the same natural orbitals in the projected state as in the unprojected state. A number of special and limiting cases are considered, including that of slightly different orbitals for different spins.
Organic Liquid Scintillators. VI. Substituted Distyrylbenzenes: Scintillation Properties and Spectra of Absorption and Fluorescence
Authors: Heller Adam
Published: January 2005

The preparation, spectra of absorption and fluorescence, and the scintillation properties of 28 derivatives of trans,trans-p-distyrylbenzene are described.

Most of the soluble derivatives are efficient primary scintillators in alkylbenzene solutions and are highly efficient secondary scintillators in alkylbenzene solution of p-terphenyl. Solutions with efficiencies exceeding those of the best-reported liquid scintillation systems are described.
Vapor Pressures and Vapor Thermodynamic Properties of Some Lithium and Magnesium Halides
Authors: Hildenbrand D. L. , Hall W. F. , Ju F. , Potter N. D.
Published: January 2005

The vapor pressures of LiF, LiCl, MgF2, and MgCl2 have been measured by the torsion-effusion method. The lithium halide vaporization data have been analyzed to yield heats of sublimation of monomer and dimer species which are consistent with available data on vapor composition, heats of dimerization, and the normal boiling points. Derived heats of sublimation of monomer and dimer at 298°K are 66.5 and 71.6 kcal/mole for LiF and 51.0 and 52.0 kcal/mole for LiCl, respectively. An analysis of the data obtained here and other vaporization data on the magnesium halides indicates that the available entropy and free-energy functions for MgF2(g) and MgCl2(g) may be low by 4 to 5 cal/mole deg. Possible reasons for the discrepancy are discussed. The heats of sublimation of MgF2(g) and MgCl2(g) at 298°K are calculated to be 93 and 59 kcal/mole, respectively.
Nuclear Magnetic Resonance in Molten Salts. I. Chemical Shift of Crystalline and Molten Thallium Salts
Authors: Hafner Stefan , Nachtrieb Norman H.
Published: January 2005

Relatively large chemical shifts in the resonance frequency of the thallium nucleus are observed in both the crystalline and molten states of different thallium salts. Relative to TlNO3, which appears to be the most ionic of all thallium salts studied, the 205Tl resonance frequency at fixed field increases in the order: NO3—<Cl—<Br—<I—. The results are interpreted in terms of a second-order paramagnetic contribution to the field at the Tl nucleus, arising from an admixture of its excited states with the ground state, and the chemical shift is approximately proportional to the square of the overlap integral. Although cations and anions in the melts are partly associated, the NMR shifts of the Tl nucleus show that the cause arises from incipient covalency rather than polarization of the cation by the halide ions.

In both the crystalline and molten states, a linear paramagnetic shift with temperature is observed, which is attributed to the enhanced overlap of excited states which are induced by thermal vibrations.
Spectrum of Dissolved Molecular Oxygen
Authors: Griffith J. S.
Published: January 2005

The ligand-field splitting of the antibonding orbitals of molecular oxygen is discussed for a general solvent environment. The results are combined with a previous calculation of the splittings of the 3Σg—, 1Δg, and 1Σg+ terms to give a possible interpretation of the observed 630 mμ emission line of dissolved molecular oxygen.
Vibrational Spectra of Polytetrafluoroethylene: Effects of Temperature and Pressure
Authors: Brown R. G.
Published: January 2005

The infrared spectrum of polytetrafluoroethylene was investigated as a function of temperature at low pressure, and as a function of pressure at ambient temperature. The temperature dependence of absorption in the region 625–640 cm—1 is consistent with the suggestion that the band at 625 cm—1 is due to a defect with creation energy ε≈0.05 eV. A calculation of the energy increase accompanying reversal of the pitch of the molecular helix supports this suggestion. At T≈100°K, there are resolved a number of bands in the region 700–1700 cm—1 that are not apparent at ambient temperature. For T>600°K, the spectrum was found to be significantly different from a report in the literature. Application of pressure p>6 kbar results in significantly reduced absorption at 640 and 1210 cm—1. The changes with pressure support the suggestion of a planar conformation of the molecule in a phase existing only at high pressure. The Raman spectrum exhibited lines at 733 and 1378 cm—1, in good agreement with predictions based upon combination bands in the infrared spectrum.
Kinetics of Pyrolysis of Isopropyl Iodide
Authors: Teranishi Hiroshi , Benson Sidney W.
Published: January 2005

The kinetics of the pyrolysis of isopropyl iodide was investigated in the temperature range 270°∼300°C using a spectrophotometric technique for determination of I2. The reaction was found to proceed through an I atom and radical chain mechanism to yield C3H6, C3H8, and I2. The reaction velocity is determined by the slow unimolecular decomposition (5) i−C3H7I⇌ lim 65C3H6+HI.The rate data give the following equation for k5: logk5=12.96–43.5/θ (sec−1)with θ=2.303RT in kilocalories per mole. The activation energy E5 and Arrhenius factor, A5, show good agreement with the values previously reported by Jones and Ogg.

The contribution of a reported autocatalytic reaction to the velocity of pyrolysis is found to be negligibly small or less than 8% of that of the unimolecular decomposition process throughout the temperature range of the present experiment.

There is evidence for the beginnings of a falloff in rate constant with pressure at about 30 mm Hg. At 15 mm Hg the falloff does not exceed 25%.

Combination of the rate constants for the forward and reverse reactions leads to an equilibrium constant K5.6 lower by a factor of about 2 than that determined previously from direct equilibrium studies. It is proposed that the kinetic constant is probably the more reliable. Values of ΔS5.6 and ΔH5.6 computed from the kinetic data are in excellent agreement with independent estimates.
Computed Potential Curve and Spectroscopic Constants for Beryllium Oxide Ground State in Molecular Orbital Approximation
Authors: Yoshimine M.
Published: January 2005

A set of single-configuration self-consistent field molecular orbital wavefunctions for the 1Σ ground state of BeO is presented. A potential curve which is approximately 0.3 eV above the Hartree—Fock potential curve for the molecule is presented, together with the results of a spectroscopic analysis on it. A further calculation at a nuclear separation corresponding to the minimum in the computed potential curve, which gives a total molecular energy of —89.44787 a.u., is presented. This is probably less than 0.1 eV above the Hartree—Fock limit. The mean value of the dipole moment of the molecule computed with this wavefunction is 7.29 D. A comprehensive selection of other mean values computed at points along the potential curve, and for the more accurate calculation at the minimum in the curve, is given.
On the Calculation of Multicenter Two-Electron Repulsion Integrals Involving Slater Functions
Authors: Bonham R. A. , Peacher J. L. , Cox H. L.
Published: January 2005

Integral transforms are used to evaluate many-center two-electron repulsion integrals involving Slater s-type functions. The reduction of a general four-center integral of this type to a form convenient for computational purposes is presented. The technique described has the important advantage that all lesser many-center and one-center integrals can be obtained from the four-center case by proper choice of constants. The form of the result is such that simple single-precision numerical techniques yield rapid and accurate evaluations of many-center integrals. Several numerical examples are presented.
Absorption Spectra of H2 in the Vacuum-Ultraviolet Region. I. The Lyman and the Werner Bands
Authors: Namioka T.
Published: January 2005

The absorption spectrum of the H2 molecule has been studied in the wavelength region 930–840 Å with a 6.8-m grazing incidence vacuum spectrograph in combination with the helium continuum. The Lyman and the Werner bands have been extended to their dissociation limits. The results of the rotational analysis of these bands are given. Behavior of the C 1Πu potential curve near the dissociation limit and predissociation found in the v = 13 level of the C state are also discussed.
Phosphorescence in Nucleotides and Nucleic Acids
Authors: Bersohn R. , Isenberg I.
Published: January 2005

As a sequel to earlier work by Steele and Szent-Györgyi, the phosphorescence of DNA, polyadenylic acids, and individual nucleotides in a water—glycerine glass at 77°K has been studied. Under these conditions, our experiments lead to the following conclusions: (1) Purine bases phosphoresce but pyrimidine bases do not, (2) the emission from DNA is the sum of independent emissions from guanine and adenine, and (3) if certain assumptions are valid, the triplet excitation is a delocalized exciton. Addition of paramagnetic ions to a polynucleotide results in quenching of the phosphorescence. If this effect is studied quantitatively, the diffusion coefficient of the exciton can be measured. This diffusion coefficient should be sensitive to the degree of order in the polynucleotides and to their composition.
Self-Consistent-Field Theory. II. The LCAO Approximation
Authors: Fraga Serafin , Birss Fraser W.
Published: January 2005

In Part I of this series, eigenvalue equations which apply to any electronic system were developed by means of a general coupling operator. These equations are here adapted to the method of linear combinations of atomic orbitals. The resultant matrix equations are applied to the helium atom for the configurations: 1S, (1s)2; 3S, (1s) (2s); 1S, (1s) (2s), using Slater 1s and 2s orbitals as basis functions.
Self-Consistent-Field Theory. IV. LCAO Approximation for Excited States
Authors: Birss Fraser W. , Fraga Serafin
Published: January 2005

The pseudo-eigenvalue equations previously obtained for any state of an electronic system are brought into the form required by the LCAO approximation. The matrix formulation involved is discussed and some practical methods for reducing the value of the maximum error of the evaluated energy are given.
Nuclear Magnetic Double Resonance Spectrum of Ammonia
Authors: Anderson Jay Martin , Baldeschwieler John D.
Published: January 2005

If the magnitude of the second rf field is small, proton nuclear magnetic double resonance spectra of ammonia, recorded by sweeping the magnetic field, are in good agreement with a calculation based on a treatment of double resonance which neglects relaxation effects. To calculate the width of spectral lines it is assumed that one relaxation mechanism is dominant, and that linewidths are small compared to the separation of a given multiplet. With these assumptions, a linewidth can be associated with the lifetimes of states giving rise to that line. The calculation of field-sweep double resonance spectra is discussed in detail, and calculated spectra are displayed by photographing traces formed on the on-line oscilloscope of an IBM 7090 digital computer. For larger magnitudes of the second rf field, the treatment neglecting relaxation fails to describe adequately the observed field-sweep double resonance spectra. A limited calculation based on the density matrix treatment of double resonance indicates that the effect of the second rf field on line shape is significant. The density matrix theory presented here has been extended to include exactly overlapping lines, but neither degenerate energy levels nor partially overlapping lines are considered.
Theory of a Micromethod for Determining Surface Tensions
Authors: Heller Wilfried
Published: January 2005

The theory of a method is developed which will allow one to determine the surface tension of liquids or solutions on samples as small as 10—4 ml. The method is therefore of particular interest for biophysical work. The method is based upon the inequality of surface pressures of a liquid column contained in a conical capillary. The somewhat unwieldy final equations arrived at can be greatly simplified if the solid angle of the cone is small and the contact angle is small or very large.