bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrical Conductivity in Flame Gases with Large Concentrations of Potassium
Authors: Mullaney G. J. , Kydd P. H. , Dibelius N. R.
Published: April 2005

The conductivity of the hot gases from propane-oxygen flames containing potassium has been measured in a coaxial graphite cell. In the temperature range 1800–2400°K with potassium concentrations of 0.01–1.0% by weight, the measured conductivity agrees with that calculated from the Saha equation and a ``free-path'' kinetic equation. A constant value of 1×10−15 cm2 was used as the cross section for collision between electrons and the combustion products in this calculation. At higher potassium concentrations, up to 7½% by weight, the electron-potassium atom cross section becomes important but a value of about 10−15 cm2 gives fair agreement with the data. At low temperatures and high cell voltages, current saturation resulting from the limited electron emissivity of the graphite was observed.
Excitation and Amplification of Cyclotron Waves and Thermal Orbits in the Presence of Space Charge
Authors: Adler R. , Ashkin A. , Gordon E. I.
Published: April 2005

The effect of space charge on the motion of the entire beam and the internal orbits of individual electrons in the transverse fields of cyclotron-wave amplifiers is considered. It is shown that the cyclotron-wave couplers excite the motion of the entire beam and have no influence on the internal motion. With sufficiently high space charge, the amplification of the cyclotron wave in quadrupolar fields is not accompanied by internal-orbit amplification. Experiments illustrating the difference between orbit pumping and wave pumping are described. It is concluded that space charge plays a vital role in allowing high gain without beam expansion and interception.
Application of Ferroelectricity to Energy Conversion Processes
Authors: Clingman W. H. , Moore R. G.
Published: April 2005

The principles of the conversion of heat energy directly into electrical energy by use of a ferroelectric material heat cycled in the neighborhood of its Curie point are described. A simplified expression for the energy conversion efficiency is derived, and reasonable values for appropriate parameters are used to obtain a numerical value for the efficiency under given operating conditions. The inadequacies of this simplified expression are discussed, and a general expression is derived. The results of the general analysis are compared with those based on the simplified method. The analysis shows that for barium titanate the exact theory predicts a higher efficiency than the simplified theory, and that in general the efficiency increases with increasing externally applied electric field and with increasing heat source temperature. For feasible operating conditions, the efficiency is in the range of 0.5%–1.0%. Future possibilities for ferroelectric energy converters are discussed.
Proposed Diagnostic Method for Cylindrical Plasmas
Authors: Shmoys J.
Published: April 2005

For a cylindrically symmetric plasma column whose electron density N is a slowly varying, monotonically decreasing function of radius r, it is possible to calculate explicitly both the diffraction pattern from the knowledge of N(r) and, conversely, N(r) from the knowledge of the diffraction pattern. If the diffraction pattern is obtained experimentally, N(r) can be calculated by a cumbersome numerical procedure. Instead of doing this, the diffraction pattern can be approximated by one of a family of convenient analytical expressions for which the integration can be carried out easily. Alternatively, one can attempt to infer N(r) by assuming a functional form for N(r) with one or more parameters, calculating the diffraction pattern, and comparing it with the observed one.
Ni-Fe Single-Crystal Films and Their Magnetic Characteristics
Authors: Verderber R. R. , Kostyk B. M.
Published: April 2005

Single-crystal, 80–20 Ni–Fe thin films have been grown by the vacuum deposition of Ni–Fe alloy onto the (111) and (100) crystal face of CaF2 single-crystal substrates. The orientation of the thin films has been determined by the Geiger counter x-ray reflection technique. The crystal orientation developed in the Ni–Fe thin films is dependent upon the substrate temperature and the crystal face of the substrate upon which the Ni–Fe is deposited. The coercive force, rotational saturation field, and selectivity of the thin films are measured on a 60-cycle hysteresis loop tracer and compared to the magnetic properties of the films deposited upon amorphous substrates.
On Dislocation Interactions in the fcc Lattice
Authors: Hirth J. P.
Published: April 2005

Long- and short-range interactions of dislocations and the likely result of dislocation intersections in fcc lattices are assessed. Of the 24 possible secondary glide systems which could interact with a primary system, 12 promote work hardening by providing strong blocks to primary glide propagation, while 12 provide only weak blocking or no blocking. The original Lomer-Cottrell barrier is found not to exist as an extended barrier; however, several other strong barriers may be extended.
Motion of 180° Domain Walls in BaTiO3 under the Application of a Train of Voltage Pulses
Authors: Miller Robert C. , Savage Albert
Published: April 2005

A study has been made of the sidewise motion of 180° domain walls in single-crystal BaTiO3 under the application of a train of voltage pulses. Measurements of the sidewise wall velocity as a function of the pulse amplitude, pulse width, and pulse repetition rate can be explained in terms of a surface layer model recently proposed for BaTiO3. These data constitute the first experimental verification of some of the important phenomena consequent on the model. This model assumes that a surface charge density of 2Ps, where Ps is the spontaneous polarization, is deposited immediately behind an advancing 180° domain boundary on the interface between the bulk ferroelectric material and the anomalous surface layer. This charge distribution gives rise to an electric field Eb′ in the bulk of the material with a component opposite in direction to the field applied to move the wall. It is found that relaxation of Eb′ begins in about 0.3 msec and continues for times in excess of 1 sec. This relaxation is not due to a simple, single time-constant, mechanism. Any fast relaxation, if present, must take place in times less than 1 μsec. After a 180° wall is at rest sufficiently long so that relaxation of Eb′ has occurred, application of an external applied field results in a wall velocity which depends on the magnitude of the wall displacement. In particular, the wall velocity decreases (due to Eb′ which increases) with increasing wall displacement. Analyses of the data show that the lateral or sidewise range of the field from the elements of charge which give rise to Eb′ is of the order of 2000 A so that once the wall has moved this distance, the effect of Eb′ at the wall, and hence the wall velocity, becomes constant. With thin crystals in the absence of an external applied field, Eb′ gives rise to wall displacements of the order of 100 A in a direction opposite to that of the wall motion which produced Eb′. The decrease in wall velocity observed when the wall displacement per pulse is of the order of a unit cell is consistent with a nucleation-controlled mechanism proposed earlier for the wall motion.

Pulse data on crystals with different impurity concentrations and electrode materials show that the relaxation of Eb′ and the lateral range r, and hence the surface layers inferred from these data, are not markedly dependent on these parameters. Other data on the dc wall velocity indicate that for a velocity of 10−3 cm/sec, the potential drop across the surface layer is 1.0±0.1 v, and that it is independent of the crystal dopings and the electrode materials tested. These data indicate that the average field in the bulk required for a given wall velocity is not a constant independent of the type of electrode or the impurity concentration. The approximate constancy of the measured characteristics of the surface layers makes the dependence of the wall velocity on the impurity content and the electrode material difficult to explain in terms of the model considered.
Backward-Wave Microwave Oscillations in a System Composed of an Electron Beam and a Hydrogen Gas Plasma
Authors: Targ R. , Levine L. P.
Published: April 2005

A traveling-wave interaction structure is used to investigate the properties of a low-density plasma formed by the interaction of an electron beam with hydrogen gas. In this experiment, microwave oscillations near the electron cyclotron frequency are observed as the result of growing waves in a beam plasma interaction. Electron densities are determined by observing the correlation between the measured frequencies of oscillation and the theoretical predictions of [A. W. Trivelpiece and R. W. Gould, J. Appl. Phys. 30, 1784 (1959)] relating to backward-wave propagation in a beam-plasma system in a magnetic field. This electron density was verified by observation of the shift in the resonant frequency of a microwave cavity containing the plasma. The shift in the resonant frequency of the cavity gives a direct measurement of the electron plasma frequency and, hence, the electron density.
Calculation of the Maximum Efficiency of the Thermionic Converter
Authors: Ingold John H.
Published: April 2005

A theoretical analysis of the efficiency of a thermionic converter is made in terms of the following parameters: Va, the potential difference between the top of the potential barrier in the interelectrode space and the Fermi level of the anode; VL, the potential drop across a load impedance in series with the converter; and Vl, the potential drop in the necessary electrical connection to the cathode. The analysis is carried out by developing an expression for the efficiency of the converter and then maximizing this expression with respect to VL and Vl. This method yields optimum values of load impedance, cathode lead geometry, and cathode work function in terms of Va, cathode temperature, cathode emission constant (usually denoted by A), and effective emissivity of the cathode. A hypothetical example is worked out numerically and the results show that (1) a low value of Va is required for high efficiency, and (2) relatively low values of cathode work function are required for maximum efficiency at ordinary cathode temperatures.
Creep Behavior of Pore-Free Polycrystalline Aluminum Oxide
Authors: Folweiler Robert C.
Published: April 2005

Creep in pore-free polycrystalline aluminum oxide has been studied as a function of temperature, grain size, and strain rate. The behavior may be described byσαd2ε̇, where d is the mean grain diameter. Deformation is not controlled by basal slip but by a diffusional creep process as described by Nabarro and Herring, [F. R. N. Nabarro, Conference on Strength of Solids (The Physical Society, London, 1948), p. 75; C. Herring, J. Appl. Phys. 21, 437 (1950)].
Influence of Conductivity Gradients on Galvanomagnetic Effects in Semiconductors
Authors: Bate R. T. , Beer A. C.
Published: April 2005

An approximate solution is found of a boundary-value problem arising from the continuity equation in an inhomogeneous semiconductor, leading to rotational current vectors. Results are used to predict the effect of carrier-concentration gradients on magnetoresistance. The predicted weak-field effects are especially significant in degenerate semiconductors and n-type III–V intermetallics where the ``intrinsic'' magnetoresistance is small. In strong fields, even small gradients in carrier concentration can completely alter the field dependence of the magnetoresistance. Experimental results indicate that transverse currents, which do not occur in the simple case discussed, do appear in general, and further perturb the magnetoresistance. The influence of inhomogeneous magnetic fields is discussed briefly.
Induction-Coupled Plasma Torch
Authors: Reed Thomas B.
Published: April 2005

A new method of generating a stable plasma at atmospheric pressure using inductive coupling at a frequency of several Mc is described. Methods of starting and operating this plasma in argon, and mixtures of argon with helium, hydrogen, oxygen, and air are discussed. The Fowler and Milne method was used to measure the temperature profile of the plasma under various conditions of gas flow and composition, and at several power levels. Measured peak temperatures ranged from 14 000°–19 000°K. The power losses from the plasma in the form of convection, radiation, and conduction to the nozzle walls were measured under the same conditions. Total power transferred to the plasma ranged from 1.6–3.1 kw which was approximately 50% of the input power. The extent to which local thermal equilibrium prevails in the plasma is discussed; the available evidence indicates that under the operating conditions described herein, equilibrium is closely approached.
Use of PrCl3 in a Solid State Infrared Quantum Counter
Authors: Porter John F.
Published: April 2005

A survey of the salts of the rare-earth series shows that anhydrous PrCl3 has energy levels and selection rules suitable for use in a solid state infrared quantum counter as proposed by Bloembergen [N. Bloembergen, Phys. Rev. Letters 2, 84 (1959)]. Two suitable schemes are proposed, one for detection at 2.33 μ and a second for detection at 104 μ. Consideration is given to isolation of the final detector from the pumping signal and a suitable experimental arrangement for unambiguously determining proper operation is shown.
Cross-Doping Agents for Rutile Masers
Authors: Chester P. F.
Published: April 2005

The EPR spectra of nonstoichiometric rutile and rutile doped with tantalum, niobium, and cerium have been examined at helium temperatures. Ta4+ and Nb4+ have short spin-lattice relaxation times and appear to be suitable for cross doping in maser applications.
Mercury Ion Beam Sputtering of Metals at Energies 4–15 kev
Authors: Wehner G. K. , Rosenberg D.
Published: April 2005

Sputtering yields for 14 metals from the 4th, 5th, and 6th periods were measured for normally incident Hg+ ions at energies between 4–15 kev. The sputtering rate was determined by measuring the time required for the ion beam to pierce a target foil. Results for the various metals show that yields at high energy behave similarly to yields previously found at lower ion energy; i.e., are closely linked to the position of the metal in the periodic chart. Yields increase in the 4th period from Ti through V, Fe, Co, Ni to Cu and in a similar fashion in the 5th period to Ag and in the 6th period to Au. It is believed that Cu, Ag, and Au atoms with their more closely filled d shells behave more nearly like hard spheres and always produce the highest sputtering yields.
Determination of the Maximum Lattice-Chain Energy from Sputtering Yield Curves
Authors: Harrison Don E.
Published: April 2005

An analysis is presented which suggests that the ``ankle energy,'' that is, the energy at which the experimental sputtering ratio curve begins to form a low-energy tail, is the maximum energy which the metallic lattice can propagate in a close-packed direction. The effect appears to depend only upon the existence of a chaining threshold, and not upon the mathematical model of the sputtering process. The equivalence is demonstrated for the author's statistical model, and for the primary lattice ion model of Kinchin and Pease [G. H. Kinchin and R. S. Pease, Repts. Progr. in Phys. 18, 1 (1955)].
Experimental Study of Intermetallic Diffusion in Large Temperature Gradients
Authors: Meechan C. J.
Published: April 2005

Temperature gradients in the range 2000°C/cm–3000°C/cm have been imposed across the interface of binary diffusion couples fabricated from fcc metals. The systems investigated were Au–Ni, Cu–Ni, γFe–Ni, γFe–Pd, and Ni–Pd. It was found that chemical diffusion in these systems was influenced in varying degrees by the temperature gradient. Suggestions are given for the manner in which the temperature gradient may affect the various contributions to chemical diffusion.
Oxygen Adsorption on Silicon and Germanium
Authors: Hagstrum Homer D.
Published: April 2005

Data are presented which yield relative magnitudes of the initial, room-temperature sticking probabilities S0 of nitrogen on clean tungsten and oxygen on clean silicon and germanium. Taking S0 to be 0.35 for N2 on W, we obtain 1×10−2 and 8×10−4 for S0 of O2 on Si and Ge, respectively. Data are also given concerning the temperatures at which the atomically clean surface is thermally regenerated from the oxygenated surface for both Si and Ge.
Gallium Arsenide Esaki Diodes for High-Frequency Applications
Authors: Burrus C. A.
Published: April 2005

Esaki diodes which show promise of usefulness into the millimeter-wave region have been made from both p- and n-type gallium arsenide. Both diodes were alloyed junctions having point contact geometry and dimensions. The fabrication of these diodes is briefly described, and their initial performance as oscillators in mechanically simple circuits is discussed. Fundamental oscillations to 103 kMc have been obtained.
Precipitation of Helium along Dislocations in Aluminum
Authors: Murray G. T.
Published: April 2005

Helium was generated in an Al-0.1 at. % Li alloy by transmutation of the Li6 atoms during neutron irradiation. During subsequent heating of the specimens, the helium appeared to precipitate in the form of small ``bubbles.'' On using a dislocation etchant it was found that (a) the regions of largest dislocation density also contained the highest cavity density, (b) in some regions each dislocation etch pit was associated with a cavity, and (c) in other regions a series of cavities appeared to delineate the track of a dislocation. It is believed that the helium precipitates along the dislocations in the form of continuous or semicontinuous cylindrical cavities.
Study of Li–O Interaction in Si by Ion Drift
Authors: Pell E. M.
Published: April 2005

Ion drift in a reverse-biased n-p junction has been used to measure effective drift mobilities of Li+ between 20°–125°C in Si samples containing oxygen concentrations up to 1.3×1018 atoms/cm3. Previous experiments have indicated that under such conditions, the Li+ and oxygen will combine to form a complex of the form LiO+. The ratio of the effective drift mobility of Li+ in such samples to the known drift mobility of free Li+, when measured as a function of temperature, can be used to determine the dissociation constant of LiO+. Thus, at an oxygen concentration of 1.3×1018 atoms/cm, the diffusion constant at 50°C is reduced from 1.7×10−13 cm2/sec to (7.6±2.2)×10−16 cm2/sec by the Li+–O interaction. From this and measurements at other temperatures, the dissociation constant of LiO+ can be calculated, yielding C=(5.8×1015)±30% at 50°C with an activation energy of 0.42±0.03 ev, or more generally, C=(0.5–8.5)×1022 exp−[(0.42±0.03)e/kT]. At high concentrations the effective drift mobility is found to be inversely proportional to the oxygen concentration, in accordance with the model. The use of this technique for the measurement of oxygen concentrations below 1017 atoms/cm3 is discussed, and some examples of such measurements are given.
Recombination Kinetics for Thermally Dissociated Li–B Ion Pairs in Si
Authors: Pell E. M. , Ham F. S.
Published: April 2005

The kinetics of a diffusion-limited pairing reaction between oppositely charged impurity ions in a solid have been studied by observing the capture of mobile Li+ ions by B− ions in Si. The kinetics were determined by measuring resistivity vs time after the method of Reiss, Fuller, and Morin [Bell System Tech J. 35, 535 (1956)]; as pairing proceeds, the resistivity decreases because of the disappearance of the charged impurity scattering associated with unpaired ions. Measurements were made between 2° and 35°C. The observed kinetics are not of first order, and are best described by a model in which pairing is largely a random process with little correlation between particular Li+ and B− ions. Diffusion constants of Li+ calculated from the kinetics are in accord with previous ion-drift results.
Properties of Polyvinylidene Fluoride. I. Dielectric Measurements
Authors: Wentink Tunis
Published: April 2005

Dielectric constant (K) and loss tangent (tan δ, the dissipation factor) measurements on the plastic polyvinylidene fluoride have been made over the frequency range 50 cycles to 9800 Mc at room temperature. Pronounced anomalous dispersion in K and a peak in tan δ near 10 Mc were observed. Theoretical and practical applications of the data are briefly mentioned. This material has an unusually high dielectric constant and is quite lossy, especially when compared to the chemically and structurally related plastics polyethylene and polytetrafluoroethylene.
Electric Strength of Rutile Single Crystals
Authors: Powers D. A. , Johansen I. J. T.
Published: April 2005

The breakdown strength of rutile crystals has been measured ∥ and ⊥ to the optic axis. The dc breakdown is a thermal process occurring at a power level of 2 kw/cm3 for the particular sample size and test cell used here, with field strengths of 20 kv/cm ∥ to the axis and 120 kv/cm ⊥. Impulse measurements at 1-μsec rise time required special techniques of sample and electrode preparation in order to prevent field distortion and surface breakdown. Breakdown strengths of 570 kv/cm ⊥ and 690 kv/cm ∥ to the optic axis were measured.
Initiation of a Low-Density PETN Pressing by a Plane Shock Wave
Authors: Seay G. E. , Seely L. B.
Published: April 2005

Plane constant-pressure shock waves were used to initiate wedge-shaped pressings of PETN (pentaerythritol tetranitrate). The shocks entered the PETN from brass or Lucite plates. Shock pressures in the plates and depths at which the PETN was initiated were measured with a streak camera. It was found that a 50-kbar shock in the brass was barely sufficient to initiate granular PETN pressed to a density of 1.0 g/cm3. This corresponded to a derived pressure of about 2½ kbar in the PETN pressing. It was further shown that the interstitial gas had no effect on the depth of initiation.
Parametric Coupling between the Transverse Waves on O- and M-Type Beams
Authors: Klüver J. W.
Published: April 2005

The coupling between transverse waves on a ``no-space-charge'' beam model via an rf pump field is investigated. It is found that the pump field should be two-dimensional in order to couple only two waves together. For high-frequency pumping only waves of same polarization can couple together, for low-frequency pumping only two waves of opposite polarization can couple together. For high-frequency pumping no ``spilling'' of higher-order noise frequencies will occur. For low-frequency pumping no ``spilling'' will occur if the pump field is purely circularly polarized. Except for cyclotron-cyclotron wave coupling the pump wave will always be in synchronism with a beam wave and thus interact actively or passively with the beam. The effect of this coupling is investigated.
Electrical Conductivity and Thermoelectric Effect in Single-Crystal TiC
Authors: Hollander Lewis E.
Published: April 2005

Single-crystal TiC exhibits a positive temperature coefficient of resistivity with a resistivity in the [100] direction of 200±20 μohm cm. The thermoelectric power ΔV/ΔT referenced against copper at room temperature is 7.8±0.6 μv/°C and indicates n-type conduction. No hydrostatic piezoresistivity was observed. The predominant cleavage plane for single-crystal TiC is {100}. It can be concluded from P vs T and thermoelectric data that single-crystal TiC has metallic-type conduction, and the predominant charge carriers are electrons.
Imaginary Part of X-Ray Scattering Factor for Germanium. Comparison of Theory and Experiment
Authors: Batterman Boris W.
Published: April 2005

The imaginary part of the x-ray scattering factor for germanium is calculated from dispersion theory and individual Hartree-Fock electron scattering factors and is compared with Hunter's experimental values measured with anomalously transmitted x rays. The agreement is quite good and verifies the treatment of anomalous transmission by the dynamical theory of diffraction. It is shown that the imaginary part of the scattering factor can be related directly to the form factor of the L electrons in germanium and it is concluded that their charge distribution in the solid is essentially the same as in the free atom.
Electron Bombardment Damage in Silicon Esaki Diodes
Authors: Logan R. A. , Augustyniak W. M. , Gilbert J. F.
Published: April 2005

The excess current in silicon Esaki diodes has been shown to be a sensitive indicator of the density and distribution of states intorduced into the forbidden gap by electron bombardment. Both the effects of bombardment and the annealing properties of the radiation damage have been found to depend upon the specific donor in the n-type region of the diode. The average bombardment dose of 1-Mev electron/cm2 needed to increase the excess current density by 1 amp/cm2 at a bias of 0.3 v is 1.2×1016 for P-doped diodes and 0.8×1016 for Sb- or As-doped diodes. Upon annealing in an inert atmosphere, at temperature in the range 300°–400°C, the bombarded diode is restored to its original characteristics. While the annealing studies reveal novel interactions, they show considerable similarity with other work where the radiation damage was monitored by carrier lifetime or conductivity measurements. Structures observed in the I–V characteristics during the annealing indicate that the bombardment-induced levels at Ev+0.27 and Ev+0.06 are due to pairing of a primary defect (probably a vacancy) with an arsenic and a phosphorus impurity atom, respectively.
On the Theory of Amplitude Distribution of Impulsive Random Noise
Authors: Furutsu K. , Ishida T.
Published: April 2005

Two phenomenological models are considered by which impulsive random noises can be described: (a) Poisson noise, consisting of the superposition of independent, randomly occurring elementary impulses. Much electronic noise belongs to this type and the familiar physical examples are precipitation noise, ignition noise, and solar ``static.'' (b) Poisson-Poisson noise, consisting of the superposition of independent, randomly occurring Poisson noise, each type of Poisson noise forming a wave packet of some duration. Atmospheric noise is a representative example of the latter type. The attempt at first is made to deduce the general amplitude distribution for each model; then, because the noise sources in nature are spatially distributed and noise strength decreases with distance so that the amplitude of the received noise sometimes depends seriously on this spatial distribution of noise sources, the amplitude probability distributions are considered according to the two typical cases of the discrete and continuous spatial distributions, and are compared with those of actual atmospherics. Moments of even order and correlation functions are also calculated for each model. Finally, the dependence of the assumptions used on amplitude probability distribution are discussed. The distributions obtained are, in some cases, found to be independent of the adopted models and some of the used assumptions in a wide range of noise amplitude.
Dangling Bonds in III–V Compounds
Authors: Gatos Harry C.
Published: April 2005

The model proposed by Gatos and Lavine [H. C. Gatos and M. C. Lavine, J. Electrochem. Soc. 107, 427 (1960)] for the dangling bonds of III–V compounds is discussed in the context of the available experimental facts and the objection advanced by Holt [D. B. Holt, J. Appl. Phys. 31, 2231 (1960)]. It is shown that the model as originally proposed is consistent with basic principles and experimental observations.
Electrical Resistivity of Chromium in the Vicinity of the Néel Temperature
Authors: Marcinkowski M. J. , Lipsitt H. A.
Published: April 2005

Previous work by other investigators has shown that a sharply cusped minimum occurs in the resistivity-temperature relationship for fully recrystallized chromium at the Néel temperature, i.e., 35°C. Plastic deformation, on the other hand, eliminates this minimum, and in addition gives rise to a pronounced change in the resistivity-temperature relationship over a wide range of temperatures centered about the Néel temperature. These results have been corroborated in the present paper. Furthermore, this behavior has been analyzed and interpreted in terms of the strong dependence of the Néel temperature on hydrostatic stresses which are thought to arise from the presence of dislocations in the deformed material.
Electrically Imploded-Exploded Aluminum Tube
Authors: Cnare Eugene C.
Published: April 2005

A high-energy exploding wire facility has been used to investigate pinch effects in thin-walled aluminum tubing. The experiments carried out consisted of subjecting the tubing to the discharge of a 141-kj capacitor bank and observing its motion by flash radiography and by high-speed sequential photography. Each tube first imploded uniformly, then broke down into an arc discharge in a manner similar to that of solid exploding wires. The implosion or pinch phase is adequately accounted for by the magnetic forces of the current discharge first acting against the mechanical strength of the tube walls and then, after melting, against the wall inertia and the retarding force of the air being compressed within the tube.
Vapor-Phase Growth of Single Crystals of II–VI Compounds
Authors: Piper W. W. , Polich S. J.
Published: April 2005

A method of growing doped single crystals of II–VI compounds a few cm3 in size is described. The crystal is grown from the vapor phase in a closed moving crucible which permits an efficient utilization of the charge and flexibility in the dimensions of the crystal.
Corbino Disk Magnetoresistivity Measurements on InSb
Authors: Green Milton
Published: April 2005

Magnetoresistivity measurements employing ``Corbino disk'' geometry have been made, at temperatures of 77°, and 203°K, and at approximately room temperature, on a slice of fairly high-purity, single-crystal, n-type InSb (probably compensated) with excess impurity concentration ND—NA of about 7×1015. In a series of measurements the ratios of the resistance at 20 kgauss to that at zero field, for the temperatures and in the order listed above, were found to be approximately 23, 23, and 33. The maximum magnetic coefficients of resistance, in the same order, were approximately 0.87, 0.70, and 0.50 per kgauss occurring approximately at fields of 0.7, 1.0, and 2.6 kgauss, respectively. Mobilities were determined by both Hall effect and low-field magnetoresistivity, and were found to agree within a few percent. The values were, in the same temperature order, 7.3, 5.3, and 4.5 m2/v sec. Temperature cycling and aging appear to cause a reduction in area of soldered contacts to the specimen. Very slight variations of magnetoresistance with the polarity of current through the specimen were observed. An explanation is given; calculations are of the same order of magnitude as experimental observations.
p-Type Photoconductivity and Infrared Quenching in Electron-Bombarded CdS
Authors: Kulp B. A. , Kelley R. H.
Published: April 2005

A platelet-type crystal of pure cadmium sulfide 46 μ thick was irradiated first with 100-kev electrons to reduce the number of sulfur interstitials, than for 400 μa-hr/cm2 with 150-kev electrons to produce an excess of sulfur vacancies. At room temperature, photoconductive peaks were observed at 0.67, 0.9, and 1.4 μ. Point-contact rectification was used to determine that the 0.67-μ peak was due to electronic conduction and the 0.9- and 1.4-μ peaks were due to hole conductivity. A ``quenching'' experiment, i.e., simultaneous irradiation with bandgap light and infrared light of variable wavelength, at room temperature shows the 0.67-μ photopeak and quenching at 0.9 and 1.4 μ. In a separate experiment, the 1.4-μ quenching band was partially removed from a platelet-type crystal by bombarding at 100 kev. This bombardment also removed edge emission from this crystal. The temperature dependence of the 1.4-μ quenching band and of the intensity of edge emission as observed by Reynolds suggests that the centers for edge emission and for the 1.4-μ quenching bands are actually the same center, namely the sulfur interstitial in different ionization states.
Hydromagnet: A Self-Generating Liquid Conductor Electromagnet
Authors: Kolm Henry H. , Mawardi Osman K.
Published: April 2005

A novel liquid electromagnet is investigated in which the exciting current is generated within the solenoid by forcing the liquid conductor radially inward through the space between two coaxial cylinders placed in an axial magnetic field. The tangential current thus generated within the flowing conductor adds to the initial applied field so that the device behaves like a self-excited, short-circuited homopolar generator. It is shown theoretically that for low values of the magnetic Reynolds number, the amplification of the magnetic field is a quadratic function of this number and that the total dissipation depends on the square of the amplification and on the cube of the hydrodynamic Reynolds number. The experimental findings are in reasonable agreement with the theory.
Formation Conditions and Structure of Thin Epitaxial Silver Films on Rocksalt
Authors: Sloope Billy W. , Tiller Calvin O.
Published: April 2005

A comprehensive experimental investigation of the effects of formation conditions on the structural characteristics of thin, single-crystal Ag films vapor deposited onto synthetic NaCl single crystals is reported. Formation conditions studied include: preannealing heat treatment of the substrate, postheat treatment of film and substrate, substrate temperature during deposition, and the rate of deposition. It is shown that an epitaxial temperature as such does not exist, and that the minimum deposition temperature for the formation of single-crystal films is rate dependent. Crystalline structure, porosity, and stacking fault density of the films are related to the rate of deposition, deposition temperature, and thickness.
Anodic Oxidation of Germanium
Authors: Gabor T.
Published: April 2005

On anodic polarization of etched samples of n-type or near-intrinsic p-type germanium, striations are formed. The periodic depletion of holes is advanced as a tentative explanation of the phenomenon.
Proposed Method of Measuring Thermal Diffusivity at High Temperatures
Authors: Cowan Robert D.
Published: April 2005

A method is proposed for determining the thermal diffusivity α of a thin solid plate, mounted in a vacuum and heated to incandescence by means of a high-energy electron beam impinging on one face of the plate, or heated by thermal radiation from an arc-imaging furnace. The beam energy is to be modulated by either a square wave or a sine wave, and the resulting temperature modulation of the faces is to be observed photoelectrically. A theoretical study is made of the possibility of deducing the thermal diffusivity of the solid from amplitude and/or phase measurements. The most practical method seems to be that which involves sine wave modulation, and measurement of the phase difference between the temperatures of the two faces of the plate. With a plate thickness of about 1 mm and frequencies of the order of 0.01–300 cps (depending on the value of α), it should be possible to measure thermal diffusivities, especially of the poorer conductors (α less than about 0.1 cm2/sec), for temperatures from 1000°K or less to the point where sublimation becomes troublesome.
Paramagnetic Maser Oscillator Analysis
Authors: Wang S. , Singer J. R.
Published: April 2005

A physical and mathematical description of maser oscillator is given with particular emphasis upon explaining the structure of the output line shape. Several approaches to the problem are taken. A qualitative description of the motion of the spin vector is followed by a derivation of the equations pertinent to the interaction of a tuned circuit (microwave cavity) and precessing spins. The resultant equation is nonlinear. Approximate solutions are given and these are plotted as output amplitude vs time. In addition, the equations are solved with numerical solutions for specific experimental conditions by means of a digital computer. The numerical results are compared with experimental data including that taken in our laboratory. The field-swept oscillator line shapes are explained by the analysis, and the steady state oscillator is described as well.
Spectral Response of Solar Cells
Authors: Dale Brian , Smith F. P.
Published: April 2005

An analysis of the spectral response of a solar cell is given which includes the effect of the electric field present in the diffused surface region. Results are presented which show the variation of response with junction depth and with carrier lifetime in both surface and bulk regions. By curve fitting, it is found that in a typical silicon cell the bulk lifetime is in the range 1–15 μsec, while the surface region lifetime is between 10−9 and 10−10 sec. Bombardment with a total flux of 3.3×1014 electrons/cm2 of 2-Mev electrons reduced the n region lifetime by a factor of 300, and the p region lifetime by a factor of 6 in a particular case.
Charged Cylindrical Tube
Authors: Ferguson T. R. , Duncan R. H.
Published: April 2005

The Fourier series for the charge density on a hollow tube of finite length is found in such a way that the Fourier coefficients are the unknowns of a system of linear equations. A machine method is used to solve the set of equations in finite order. The leading coefficient is the most accurately known at any order, and solely determines the capacitance of the tube. Capacitances are determined for various ratios of half-length to radius to an accuracy of better than 0.02%. The technique of solving the integral equation for charge density is useful in other physical problems.
A Phenomenological Theory of the Soret Diffusion
Authors: Bierlein James A.
Published: April 2005

The classical Soret diffusion problem is solved analytically for the case of unrestricted composition in a binary liquid system, taking account of the temperature-variation of the density of the mixture. Previous treatments have neglected the phenomenon of thermal dilatation entirely and have not developed a unique general solution which applies both to dilute and to nondilute mixtures.

The rigorous solution derived in the present work is similar in form to de Groot's well-known equation for dilute mixtures, but contains additional parameters characterizing the initial composition of the system and its coefficient of thermal expansion. These parameters disappear in the asymptotic approximation for a vanishing temperature gradient, but this approximation differs from that proposed by de Groot, even for dilute solutions. The asymptotic expression has practical importance for estimating the Soret coefficient and the ordinary diffusion coefficient of a system from experimental data taken during the thermodiffusional unmixing period; some examples of its application in this connection are discussed.
Magnetic Susceptibility of Liquid Ozone-Oxygen Mixtures
Authors: Brown Callaway , Hersh Charles K. , Berger Abraham W.
Published: April 2005

The data needed for analysis of liquid ozone-oxygen mixtures by measurement of magnetic susceptibility are presented. Volumetric preparation of liquid ozone-oxygen mixtures in equilibrium with the vapor phase is described. A permanent magnet at the temperature of the solutions provided the key for use of the Quincke (U-tube) method for magnetic susceptibility.

Results at — 195° and — 183°C show a linear relation between the magnetic susceptibility of the solutions and weight percent oxygen at low oxygen content. Above about 10 percent oxygen the specific susceptibility of oxygen in solution decreases significantly. At — 183°C, the ratio X8/X0 of specific susceptibility of oxygen in solution to that of pure liquid oxygen decreased from 1.30 at low concentrations to 1.13 at 27.6 percent oxygen, the two-liquid phase boundary. The limiting ratio at — 195°C was 1.42. The discontinuity in magnetic susceptibility was used to establish the compositions at the phase boundaries; 9.2 and 91 percent by weight oxygen at — 195°C, 27.6 and 70.2 percent at — 183°C.
C13 Isotope Effect in the Thermodecomposition of Ethyl Bromide
Authors: Friedman Henry L. , Bernstein Richard B. , Gunning Harry E.
Published: April 2005

The C12—C13 fractionation factor in the decomposition of gaseous ethyl bromide has been measured from 350—450°C, using samples of natural isotope abundance. The rate constants are defined as follows: CH3CH2Br→CH2=CH2+HBrk1,CH3C*H2Br→CH2=C*H2+HBrk2,C*H3CH2Br→C*H2=CH2+HBrk3.At 400°C, the C12 enrichment of the first fraction of ethylene from decomposition of the ethyl bromide is S0≡1+ε0=2k1k2+k3=1.0079±0.0006,with a temperature coefficient of — 2.8×10-5/°C.

The primary and secondary isotope effects are defined, respectively, as β=k1/k2—1 and γ=k1/k3—1; thus, to a good approximation, β+γ=2ε0. According to theory, β>γ≥0, so that ε0<β≤2ε0 and ε0>γ≥0. From the data of 400°C one then obtains as an upper limit (k1/k2)max≤1.0159±0.0012. This is significantly lower than the value k1/k2≥1.036 calculated for the rupture of an isolated C—Br bond. The present results, therefore, favor a mechanism involving the direct intramolecular elimination of HBr.
Spectroscopic Studies of Rotational Isomerism in Fluorinated Ethanes. I. 1,2-Difluoro-1,1,2,2-Tetrachloroethane
Authors: Kagarise R. E. , Daasch L. W.
Published: April 2005

The Raman spectra of solid and liquid CFCl2–CFCl2 have been investigated, and the observed frequency shifts (Δν cm—), relative intensities, and depolarization factors are presented for the latter. The infrared absorption spectra of the liquid in the 2—36-μ region, and of the solid and vapor in the 2—22-μ region have also been studied.

The behavior of the infrared and Raman spectra as a function of temperature and upon solidification was anomalous in that no changes in the relative intensities of the spectral lines were observed.

Two possible explanations of the spectroscopic data are considered, neither of which is completely satisfactory. The assumption of a single molecular species, corresponding to a large energy difference, is apparently in conflict with the number of observed Raman frequencies, while the assumption of two forms of almost equal energy (ΔH<300 calories/mole) is inconsistent with the persistence of all lines upon solidification.
Dielectric Constants of Liquid and Solid Hydrogen Sulfide
Authors: Havriliak S. , Swenson R. W. , Cole R. H.
Published: April 2005

The equilibrium dielectric constants of the disordered highest temperature solid phase show a regular increase with decreasing temperature which is in moderate agreement with Onsager's equation. Larger values than would be expected on this basis are found in the intermediate solid phase, while the values in the ordered phase below 103°K are a little larger than the square of the estimated refractive index. No evidence of relaxation effects or of electrode polarization was found in the frequency range from 15 c/s to 500 kc/s studied.
LCAO MO Study of the Phenomenon of Thermochromism
Authors: Matlow Sheldon L.
Published: April 2005

An LCAO MO calculation of the energies of the ground, planar triplet, and perpendicular triplet states of bianthrone and bixanthylene indicates that the thermally excited state in the phenomenon of thermochromism is the perpendicular triplet. Because of the uncertainty of the correct values of the parameters used, the best correspondence between the calculated and observed excitation energies that could be expected is that of order of magnitude. This is shown to be the case. The nature of the variation of the calculated values with the choice of parameters is indicated.
Approximate Method of Calculating Vibrational Frequencies of Polyatomic Molecules
Authors: Bratož S.
Published: April 2005

A new approximate method for calculating molecular vibrational frequencies is developed, based on the supposition that the molecule can be considered in zero-order approximation as a weakly coupled aggregate of partial vibrating systems, the interactions between them being taken into account by a perturbation calculation. The separation of the molecule into partial systems is discussed and a comparison is made with the results of exact calculation.
Overlaps of Trial Functions for the Hydrogen Molecule. I. Ground-State Character of the 1s A.O. Approximations
Authors: Braunstein† Jerry , Simpson William T.
Published: April 2005

The contributions of the ground state wave function in some of the trial functions for the hydrogen molecule have been evaluated as the overlap integrals of the trial functions with the thirteen term function of James and Coolidge. The rms errors and mean excited state energies are presented and the results of a binding energy calculation reported.
The Microwave Spectrum of Ethyl Fluoride
Authors: Kraitchman J. , Dailey B. P.
Published: April 2005

The microwave spectrum of ethyl fluoride has been investigated in the region from 17 to 38 kMc. The values of the rotational constants of the molecule obtained from the analysis of the spectrum are: A = 36070.30±0.10 Mc, B = 9364.54±0.10 Mc, and C = 8199.74±0.10 Mc. The following structural parameters have been fitted to these rotational constants: rCH = 1.091A, rCC = 1.540A, rCF = 1.375A, and tetrahedral bond angles. The dipole moment components along the principle axes of the molecule are μA = 1.69D and μB = 1.00D; the total dipole moment, μ = 1.96±0.03D, is oriented at an angle of 64° with respect to the C–C bond axis, or approximately 7° from the C–F bond axis. The barrier height for internal rotation is 1490±50 cm—1 (4260 cal/mole).
Sedimentation Velocity and Diffusion of a Solvated Substance
Authors: Cheng Ping-yao
Published: April 2005

Based on the contention that the driving force for the motion of a species relative to the mass flow in a particular direction is the negative gradient of total potential of that species in that direction, equations for both the sedimentation velocity and the diffusion of a solvated substance are derived. They are reduced to the usual expressions for a nonsolvated substance. The partial specific volume term in the equations of sedimentation velocity is shown to have theoretical justification. The advantages of expressing the sedimentation velocity in terms of solvated species are discussed. It is also shown that for the diffusion of a solvated species the ``thermodynamic factor'' calculated in the usual way is always greater than the gradient of chemical potential of the solvated species, except at zero concentration, by a previously neglected term arising from solvation. The effect of solvation on diffusion coefficient and on the relation between the frictional coefficients in the sedimentation and diffusion are also discussed in the light of this theory.
Molecular Calculations. III. A Modification of the Naive Semiempirical MO Method
Authors: Goodman Lionel , Shull Harrison
Published: April 2005

It is shown in this paper how the conventional naive semiempirical molecular orbital approach for conjugated hydrocarbons may be complemented by means of theoretically computed electron repulsion integrals in a manner suggested by the more rigorously founded SCF procedure. This is shown to give satisfying results in three examples with a considerable reduction in labor as compared to the complete ASMO method. The method is carried over in a natural and simple manner to substituted hydrocarbons, providing unambiguous methods of evaluating empirical resonance and inductive parameters. The concept of ``weak'' and ``strong'' substituent is developed and it is shown how these provide simple intuitive approaches to the estimation of interaction parameters in the theory. The inductive and resonance effects upon the energy levels are shown to be far from additive, and indeed are dependent upon each other. The dependence is analyzed and it is indicated which ones are important (and determinable) from various experimental situations.