bluuebunny/crossref_metadata_2025 huggingface dataset:
High-Sensitivity Magnetic Resonance by Bolometer Detection
Authors: Schmidt J. , Solomon I.
Published: April 2005

It is shown that spin magnetic resonance can be observed by a rise in the temperature of the sample, with a sensitivity equal to or better than with the more conventional electromagnetic detection methods.

An experimental demonstration is provided by a crude bolometer made of a thin copper wire with a small sample of DPPH glued in the center. A sensitivity of about 5×1011 spins, for a detector bandwidth of 1 cps has been obtained at room temperature. An important advantage is the absence of a microwave carrier signal, resulting in a very stable baseline and the possibility of using very high microwave power.

A detailed theoretical discussion shows that this method is well adapted for wide electronic lines, high frequency (up to 2-mm wavelength), low temperature, and small size samples. In favorable cases (resonance of conduction electrons in metals or semiconductors) a sensitivity of 106 spins, at liquid-helium temperature, is predicted.
Simultaneous Giant Pulses from Five Ruby Laser Oscillators
Authors: Gregg David W. , Thomas Scott J.
Published: April 2005

A laser system using bleachable-filter Q-switching has enabled us to obtain simultaneous ``giant pulses'' from five ruby laser oscillators. The beams from the different oscillators were found to be phase-locked; the beam divergence was limited by the initial ruby quality. Two other systems for obtaining simultaneous giant pulses were investigated. One involved using the giant pulse from one oscillator to switch the bleachable cells in other oscillators; the other consisted of feeding the giant pulse from one oscillator into a branching chain of amplifiers. These latter systems proved less desirable for expansion to a large number of laser rods.
Thermal Relaxation of Indium Films on Insulating Substrates between 4° and 300°K
Authors: Von Gutfeld R. J. , Nethercot A. H.
Published: April 2005

The thermal decay times of thin indium films evaporated on sapphire and quartz single-crystal substrates have been measured over a range of temperatures which, with earlier measurements, now extends from 4°–300°K. At the higher temperatures the results were found to be in good qualitative agreement with the predictions of the thermal diffusion theory of heat transport, although there were some quantitative discrepancies. The decay times characterizing the initial part of the thermal decay of a 2200-Å film on a sapphire substrate were measured to be as fast as ∼2×10−9 sec near 100°K, increasing to about 8×10−9 sec at room temperature. The decay times were found to be longest (up to ∼30×10−9 sec) below 10°K, where the heat transport is predominantly by ballistic phonon flow. The decay times for a 2700-Å film on a quartz substrate were found to lie between 13 and 30×10−9 sec in the range of temperatures from 4° to 300°K.
Effects of Pre-Irradiation Annealing on the Thermoluminescence and Dielectric Loss of LiF:Mg
Authors: Grant R. M. , Cameron J. R.
Published: April 2005

The character of the radiation-induced thermoluminescent glow peaks in LiF:Mg (70 ppm and 100 ppm by spectrographic analysis) is affected by pre-irradiation isothermal annealing. For pre-irradiation annealing below 100°C the kinetics of one of the glow peaks which appears at about 105°C has been correlated with the annealing kinetics of quenched-in Mg++—cation vacancy complexes as measured by dielectric loss techniques. After the samples have been annealed for one hour at 400°C and cooled in about 3 min to room temperature, almost all of the magnesium is found to be associated with cation vacancies. The 105°C glow peak associated with the Mg++—cation vacancy complex is proportional to the measured number of these complexes in the two samples.
Energy Distribution of Energetic Atoms in an Irradiated Medium. III. Several Species Case
Authors: Kostin M. D.
Published: April 2005

A set of coupled linear integral equations for the energy distributions of energetic atoms in an irradiated polyatomic medium is further investigated. It is found that the asymptotic collision density, the number of collisions per unit volume per unit time per unit energy between energetic atoms with kinetic energy E and thermal atoms, is proportional to 1/Eβ for a wide class of energy change probability functions. For elastic collisions, the exponent β equals 2, and the constant of proportionality is determined from the energy current. The results are used to calculate the number of displaced and replaced atoms produced by primary energetic atoms in a polyatomic medium.
Anomalous Energy Spreads in Electron Beams
Authors: Simpson J. Arol , Kuyatt C. E.
Published: April 2005

Energy distributions of 2- to 10-eV electron beams were measured in a deflection analyzer. The performance of the analyzer was monitored by use of a second one in tandem. In agreement with earlier measurements in high-energy beams the energy distribution varied with current. At low beam currents the energy distribution was Maxwellian at a temperature corresponding to the cathode temperature. As the current increased toward the beam space-charge limit, the energy width increased. The excess energy width could be fitted to a curve linear in current density and varying inversely with beam energy to the three-halves power. No shift in most probable energy was found. The results are not in quantitative agreement with the higher-energy low space-charge measurements.
Enhancement of Acoustic-Electromagnetic Wave Coupling Across a Plasma-Air Boundary
Authors: Jull E. V. , Hedvall P.
Published: April 2005

The linearized field equations for ion acoustic and electromagnetic waves in a low-pressure gas discharge or semiconductor are considered. Boundary conditions at a density discontinuity and a plasma-air surface are examined and expressions are derived for the reflected and transmitted fields excited by an incident acoustic wave. Numerical results for the power transmission through a plasma-air boundary indicate that great enhancement can be obtained in a narrow frequency range by a boundary layer of reduced density and a thickness of an odd multiple of the acoustic half-wavelength.
Phase and Order Transitions during and after Film Deposition
Authors: Behrndt Klaus H.
Published: April 2005

The transitions between phases and different states of crystallographic order in films are systematically examined. The experimental data of various workers are comprehensively connected and interpreted. By combining this evidence with theoretical considerations, the many analogies between two- and three-dimensional phase diagrams are shown. The conditions for the preferential nucleation of liquid or solid islands are given. The crystallographic order diagram pertains to equilibrium growth transitions also, and the state of order of the nuclei can be determined accordingly. These considerations yield a logical explanation for the phase and order transitions in films.
X-Ray Diffraction Measurements of Stacking Faults in Alpha Silver-Tin Alloys
Authors: Newton C. J. , Ruff A. W.
Published: April 2005

Stacking-fault probabilities and dislocation densities were studied by means of x-ray diffraction and transmission electron microscopy in both filed and compressed bulk specimens from a series of dilute silver alloys. In the filed samples the observed stacking-fault probabilities increased smoothly from 3×10−3 for pure silver to 66×10−3 for 10.3 at. % tin. The values obtained from the compressed bulk specimens were 6×10−3 and 95×10−3, respectively. Direct determinations of the dislocation densities were made in the bulk specimens (1 to 5×1011 cm−2) leading to computed values for the stacking-fault energy in the range 2 to 6 erg·cm−2, with a slight dip for pure silver. Values for the dislocation density in the filed samples were also calculated. The effect of directed residual stresses measured on the bulk specimens was shown to be negligible with respect to the low-angle diffraction line shifts attributed to faulting.
Some Effects of Mechanical Stress on the Breakdown Voltage of p-n Junctions
Authors: Hauser J. R. , Wortman J. J.
Published: April 2005

Various factors determining stress-induced changes in the breakdown voltage of Ge and Si p-n junctions are discussed. A model is developed which accounts for the multivalley band structure of semiconductors such as Ge and Si. Analytic expressions are developed for the change in breakdown voltage ΔV/VB as a function of a general stress. For Si, a linear decrease in ΔV/VB with increasing stress is predicted. The proportionality factor is of the same order of magnitude as the bandgap dependence on hydrostatic pressure. For Ge, an initial increase in ΔV/VB followed by a decrease at high stress levels is indicated. The model is shown to be consistent with reported experimental data.
Effect of Chain Conformations on the Frequency Distribution of an Idealized Chain
Authors: Jannink G. , Summerfield G. C.
Published: April 2005

The frequency distribution of a simplified carbon skeleton chain is calculated for several conformations, given by successions of trans- and gauche structures in various orders. It is found that the phonon frequency distribution is sensitive to these orders. Validity of the model and use of the results are discussed.
Glass Transitions of Ethylene Oxide Polymers
Authors: Faucher J. A. , Koleske J. V. , Santee E. R. , Stratta J. J. , Wilson C. W.
Published: April 2005

Glass transition temperatures of a very wide molecular-weight range of ethylene oxide polymers were measured by mechanical loss and by broadline NMR. Starting at about −95°C for ethylene glycol, the glass transition rises to a maximum of −17° for molecular weight 6000 and then drops off to −53° for polymers with molecular weights greater than 200 000. This unusual behavior is probably caused by the high crystallinity of the intermediate molecular-weight polymers.
Measurement of Pole Figures and Orientation Functions for Polyethylene Films Prepared by Unidirectional and Oriented Crystallization
Authors: Desper C. R. , Stein R. S.
Published: April 2005

The x-ray pole figure technique has been applied to the study of orientation in polyethylene. Wilchinsky-type orientation functions of the form 〈cos2φhkl, q〉 are determined as well as pole figures. These functions are shown to be related to the crystalline contributions to birefringence and infrared dichroism. A new method of presenting these functions on an equilateral triangle plot is introduced. Equations are presented for calculating the orientation functions for weakly diffracting [hkl] planes for materials of the orthorhombic, tetragonal, hexagonal, and cubic systems. The method of analysis is applied to various polyethylene samples, including a unidirectionally recrystallized sample (I) and to crosslinked film recrystallized at low orientation (II), and at higher orientation (III). The resulting data are interpreted in terms of various morphological models and are also correlated with birefringence. The data on (I) are consistent with a model of random orientation of a and c about the b axis. In (II) and (III) the row nucleation model and the a-axis orientation model are both inadequate. For (II) a diffusely oriented helix model is suggested; for (III) a screw dislocation model of crystal growth, with the screw axes parallel to the stretch direction, is proposed.
X-Ray Line Broadening in Isotactic Polystyrene
Authors: Buchanan D. R. , Miller Robert L.
Published: April 2005

Wide-angle x-ray line-broadening data from several samples of isotactic polystyrene with different histories of pretreatment have been obtained by diffractometer techniques. These data have been analyzed according to several theories of the separation of the line-broadening effects due to small crystallite size and to lattice distortion; the results obtained from several integral breadth methods and from full line-profile analysis via Fourier transformation are compared. In each instance, annealing produces larger crystallite sizes and smaller degrees of lattice distortion. However, the actual numerical results obtained vary with the method of separation. Some of these variations arise from questionable assumptions in particular theories of size-distortion separation and others occur because different physical quantities are determined. It is possible, for example, to obtain information concerning number-average and weight-average crystallite sizes. For one isotactic polystyrene sample, good correlation of crystallite size from wide-angle diffraction, long period from low-angle diffraction, and x-ray crystallinity is demonstrated. Experimental problems encountered in the collection of line-profile data for polymer systems are also discussed, with particular emphasis on methods of correcting data for the effects of instrumental broadening. It is shown that a simple method based upon a Gaussian approximation to the profile shapes is often adequate to carry out the instrumental broadening correction.
Preparation and Properties of Solution-Grown Epitaxial p—n Junctions in GaP
Authors: Lorenz M. R. , Pilkuhn M.
Published: April 2005

The technique of epitaxial growth from solution has been applied to GaP. Single-crystalline overgrowths up to 80 μ thick on (111)-oriented substrate crystals were obtained by the slow cooling of GaP-saturated Ga solutions. n-type overgrowths (Te-doped) on p-type substrates (Zn, O-double doped) gave planar p—n junctions free of gross defects. The I—V characteristics of these diodes show an exponential behavior of the form I=I0 exp (eV/βkT). Values for β were mostly between 1.5 and 1.8 at 300°K. At low currents, the I—V characteristics are interpreted by tunneling. The junctions emitted red light at 300°K in a broad band with the peak at about 1.77 eV (7000 Å). The emission intensity varies with I2 at low currents, changes to a linear dependence at intermediate currents, and is sublinear at high currents. The external differential quantum efficiency was measured to be as high as 7.5×10−3. The temperature dependence of the emission intensity and the efficiency were measured and are discussed.
Vacuum Evaporation of Metals for Shadow Casting
Authors: Rosauer Elmer A. , Wagner Charanne B.
Published: April 2005

Various metals in common use for shadow casting were evaporated in vacuo and their empirical evaporation efficiencies were compared with a weight method and with multiple-beam interferometry. A nomograph and appropriate correction factors were developed for rapid and accurate thin-film thickness predictions. Use of the evaporation formula to determine thickness gave values ranging from one-half to two times as much as those obtained by multiple-beam interferometry. Individual variations are believed due to alloying characteristics and physical properties of the evaporated film. A method is presented which enables thin-film thickness predictions with a high degree of accuracy for the materials used.
Induction Velometry in an Ionized Gas
Authors: Malliaris A. C.
Published: April 2005

A free jet (diameter 2r0) of ionized gas is considered under the influence of a uniform magnetic field B normal to the jet axis. Two appropriately placed electrodes sense the induced potential difference Δφ and the following relation: 〈u〉0 = Δφ/2r0B is taken as the basis for the experimental determination of 〈u〉0 defined as the velocity of the ionized gas averaged over the jet cross section. The experimental conditions and the analytical background are carefully examined. It is found that the necessary requirements are satisfied by the plasma properties, by the geometry of the experiment, and by the external circuitry so that the above relation is approximately valid within ±20% or better, depending on certain restrictive assumptions. Appreciable uncertainties arise from the existence of a gradient in the electrical conductivity of the ionized gas and from difficulties in the determination of r0. A plasma jet was generated by a radiation-cooled thrustor and four different gases were used at various mass flow rates and power levels so that a range of plasma velocities between 105 and 106 cm·sec−1 were available. The observed signals were induced by an ac magnetic field (60 cps) having an amplitude in the vicinity of 10 G. Concurrently with the measurements necessary for the determination of 〈u〉0, two other quantities were measured: the thrust F generated by the jet and the mass flow rate ṁ of the gas. For the experiments reported here, the values of 〈u〉0 and of F/ṁ are expected to agree within a few percent. Accordingly, the straight line: 〈u〉0 = α+β (F/ṁ) is determined by a least-squares fit to the data when 〈u〉0 is plotted versus F/ṁ. For the main group of data it is found that α = (0.38±0.24) × 105 cm/sec and β = 0.94±0.04. This is found satisfactory within experimental error and within the approximations made. Finally, several auxiliary experimental tests are carried out in order to obtain evidence supporting the approximations made in the main experiments.
Scattering of Phonons by Dislocations
Authors: Moss Marvin
Published: April 2005

The theories of Carruthers and Klemens of the scattering of phonons by dislocations are compared, and it is shown that Carruthers' approach yields larger cross sections in several ionic crystals: LiF, NaF, NaCl, KCl, KBr, KI, NaI, and MgO. Klemens employs a Grüneisen model for anharmonic coupling, while Carruthers deals directly with the atomic force constants. In the limited number of cases where experiments reveal the expected τ−1 ∝ ω (K ∝ T2) dependence, Carruthers' theory agrees better with the observed results, although both approaches underestimate the strength of the scattering. It is suggested that dislocations acting cooperatively might be the cause of the discrepancies.
Effect of Cleavage on the Dislocation Content of Sodium Chloride
Authors: Strom Richard G. , McCarthy K. A.
Published: April 2005

Cleavage of sodium chloride crystals is found to increase the dislocation content of the crystals in the region of the cleavage. Evidence is shown of bands of high dislocation content in large crystals, and for over-all increase in dislocation content for thin crystals. It is proposed that the dislocations produced are perpendicular to the cleavage plane and require that strains produced by cleavage are sufficient for the production of new dislocations and for the movement of inherent dislocations.
Theory of Adhesion of Small Particles
Authors: Krupp H. , Sperling G.
Published: April 2005

A theory of adhesion between small solid particles and a solid wall is presented which is based on van der Waals forces of attraction between the adherents causing irreversible deformations at their interface. The van der Waals constant is calculated from the imaginary parts of the frequency-dependent dielectric constants of the adherents. While the van der Waals constant of any pair of materials ranges, probably, between 0.5 and 9 eV, forces of particle adhesion at a given particle radius extend over several orders of magnitude owing to large variations in deformability and geometry of the interface between the adherents. Qualitatively, the results agree with experiment. The contributions of electrostatic forces to particle adhesion are estimated.
Effects of Irradiation with Protons on the Electrical Properties of Bi2Te3
Authors: Chaudhari P. , Bever Michael B.
Published: April 2005

Single crystals of p-type Bi2Te3 were irradiated near room temperature with 7.5-MeV protons. The Hall coefficient increased while the Hall mobility and the magnetoresistance coefficient decreased with increasing radiation dose; irradiation with 1.2×1016 protons per cm2 changed the compound from p type to n type. Agreement between the experimental and calculated values of the resistivity was obtained if the resistivity was assumed to be due predominantly to ionized imperfection scattering and lattice scattering. The number of defects introduced by the irradiation calculated from the experimental data was more than an order of magnitude smaller than the numbers calculated from theories of radiation damage.
A Method of Critical Magnetic-Field Measurement for High-Field Superconductors in Pulsed Magnetic Fields
Authors: Suenaga M. , Ralls K. M.
Published: April 2005

A high magnetic-field magnetization technique has been devised which allows rapid measurement of superconducting to normal transition fields (Hc2*) for bulk high-field superconductors in pulsed magnetic fields up to 200 kG. Values of Hc2* so obtained are in good agreement with those obtained by resistive techniques. A complete magnetization curve is obtained in the same time that one point could be determined for a resistive critical current density vs field curve. The significance of such a dynamic magnetization curve is discussed.
Diffusion of Copper in Iron
Authors: Anand M. S. , Agarwala R. P.
Published: April 2005

Using 64copper and the residual-activity technique, diffusion of copper in iron has been studied in both the paramagnetic and the ferromagnetic phases. The diffusivities (cm2/sec) can be described as follows: DCu/Fe=0.57 exp(−57 000/RT) (800°–1050°C, paramagnetic phase), DCu/Fe=0.47 exp(−58 380/RT) (650°–750°C ferromagnetic phase). The decrease in the diffusivity at the Curie temperature has been discussed in light of the theories of spin-ordering and the temperature dependence of the elastic constants. The results do not show a change in activation energy at the transition temperature.
Ion Sampling Considerations for a Discharge Plasma of Nitrogen
Authors: Böhme D. K. , Goodings J. M.
Published: April 2005

A quadrupole mass-spectrometric sampling probe is employed for the study of ion extraction and plasma sheath formation in a discharge plasma of nitrogen at low pressures (9 to 27 μ). The dependence of the specific ion current ratio i(N+)/i(N2+) on the potential of the sampling probe is presented for various pressures and a fixed electron temperature. Kinetic energy distribution curves for individual ionic species are obtained under a variety of conditions of sampling probe potential, pressure, and electron temperature using a retarding potential field applied at the entrance grid of a quadrupole mass filter. Interpretations of the results indicate that ion generation processes and ion-molecule collisions occurring in the sheath may strongly influence the sampling process.
Temperature Dependence of Dynamical Electron Diffraction Intensities of Polycrystalline Foils
Authors: Glaeser W. , Niedrig H.
Published: April 2005

A theory of the temperature dependence of dynamical electron diffraction intensities was developed using complex atomic scattering amplitudes. The theory is based on the two-beam approximation and can be applied to single crystals and polycrystalline foils. For thick crystals the temperature dependence of the intensities of the primary and reflected beam is approximately proportional to exp(−0BMg) with 0B>2π, in agreement with experimental values. For comparison with experiments at thin polycrystalline foils (small crystals) the corresponding case was also calculated.
Fluorescence Corrections to X-Ray Absorption in a Slab
Authors: Veigele Wm. J. , Roper N. J.
Published: April 2005

Photoelectric absorption or absorption resulting from incoherent scattering of x rays may produce secondary (fluorescent) radiation which, by escaping the absorbing material, will reduce the actual energy absorbed. This is described by reductions in linear photoelectric and incoherent scattering absorption coefficients which are functions of the incident photon energy only. For fluorescent radiation which does not escape the absorbing material, additional energy- and geometry- dependent corrections are required. These corrections are derived for a flat, finitely thick slab of infinite extent. Comparison is made with Monte Carlo computations for 100-keV x rays incident normally on a 0.1-cm-thick slab of gold.
Kinetic Energies of Ions Produced by Laser Giant Pulses
Authors: Gregg David W. , Thomas Scott J.
Published: April 2005

Kinetic energies of ions produced by focusing laser ``giant pulses'' on surfaces of Li, LiH, Be, C, Al, S, Zn, and Ag were measured. The mean-squared ion velocity and the velocity squared of the highest-energy ions detected are presented as a function of laser ``giant pulse'' peak intensity. The mean squared ion velocity increased proportionally to approximately the square root of the ``giant pulse'' peak intensity for the lower atomic weight materials, and varied with approximately the 0.33 power of the intensity for the higher atomic weight materials. Average ion kinetic energies as high as 2000 eV were detected.
Injection of Intense, Large-Diameter Ion Beams into Low-Density Gases
Authors: Martin D. H. , Hutchins C. L. , McClenny W. A. , Stallings C. H. , Wakefield R. H.
Published: April 2005

Experimental tests of a method for injection of large-diameter, intense positive ion beams into low-density gases are described. 20-keV, 15-mA beams are projected through a supersonic annular gas nozzle which furnished a large aperture (3.18 cm diam), while providing differential pumping to allow up to 30 mTorr pressure in the collision chamber. Calorimetrically measured attenuations of large argon and helium ion beams in several gases are given and compared with similar data for small-aperture beams. Possible extensions of the method are discussed.
Elastic Centers of Strain and Dislocations
Authors: Koehler J. S.
Published: April 2005

It is shown that the displacement fields and the stress fields associated with various dislocation arrangements in an isotropic elastic solid can be easily obtained by integrating the displacements found for various kinds of point nuclei of strain. Examples are given. It is found that a platelike precipitate of centers of dilatation is not completely equivalent to an edge dislocation loop. One must include, in addition, forces acting in the plane of the loop at the edge of the loop. The implications concerning the elastic force acting on point defects near a precipitate are discussed.
Effects of X-Ray Irradiation on the Self-Friction of Potassium Chloride
Authors: Jirgal G. H. , Zwicker Earl F.
Published: April 2005

The forces of static and sliding friction between mechanically polished x-ray irradiated KCl were found to satisfy the equations: F (static)=AN12+BNand F (sliding)=B′N+D′N32,where F is the force of friction, N is the normal force, and A, B, B′, and D′ are numerical coefficients. Various models of friction were examined, and it was shown that both the functional relationships between friction and the normal force and between the changes in the numerical coefficients and the F-center concentration are consistent with a modification of the theories of Bowden and Tabor and of Rabinowicz. In this modification, the coefficients are given by A/B=MW/p12B=B′=s/pD′=M′p−12,where s is the shear strength of the junctions of the contacting asperities, p is the flow pressure of the asperities, W is the work of adhesion per unit area, and M and M′ are numerical constants. The changes of the frictional coefficients A/B, B, B′, and D′ were proportional to the square root of the F-center concentration induced by the x-ray irradiation and were consistent with the theory of defect hardening proposed by Fleischer and the flow stress experiments of Nadeau and of Sibley and Sonder.
Dispersion and Damping of Oscillations in Maxwellian Plasmas with Nonuniform Zero-Order Densities
Authors: Lee Kai Fong
Published: April 2005

The dispersion and damping of oscillations in Maxwellian plasmas with zero-order density gradients are studied using the Vlasov and Maxwell's equations. The plasmas are confined by a strong axial magnetic field and the densities are nonuniform in the transverse directions. By means of a variational method, it has been found that the oscillation characteristics are governed by a parameter γ which depends on the ratio of wavelength to the scale of inhomogeneity. Physically, γ is a measure of the weighted average density, with the square of the electric field as the weighting factor. It is always greater than or equal to unity; unity being the limiting case of an infinite and homogeneous medium. As γ increases, the effective plasma density is decreased and the following changes occur: (1) The real frequency of oscillation and the phase velocity are reduced. (2) The group velocity is increased. (3) Landau damping is increased. These changes are evaluated quantitatively for Gaussian and exponential density profiles.
Electroluminescence and Conduction in Nb–Nb2O5–Au Diodes
Authors: Hickmott T. W.
Published: April 2005

Three experiments—current-voltage characteristics, electroluminescence, and photoconductivity—are consistent with the hypothesis that both holes and electrons can be injected into Nb–Nb2O5–Au diodes whose thickness varies between 90 and 3500 Å. Such diodes are strongly rectifying. For some diodes with oxide films thinner than 300 Å, J ∝ exp(eV/2kT) for diode voltages between 0.3 and 0.8 V. For oxide films thicker than 1000 Å, J ∝ V3/L5 for diode voltages greater than 1.2 V. Electroluminescence is observed from thin Nb–Nb2O5–Au diodes under forward bias at applied voltages of 1.2 V. The energy of the emitted radiation is ∼1.2 eV, independent of oxide thickness. The threshold for photoconductivity of Nb–Nb2O5–Au diodes is also ∼1.2 eV. It is proposed that an impurity band occurs in Nb2O5, 1.2 eV below the conduction band. Hole injection into the impurity band depends on the work function of the counterelectrode metal Au. Replacement of Au by a low-work-function metal, In, eliminates evidence for double injection in the insulator. Rectification is negligible in Nb–Nb2O5–In diodes. At low diode voltages, J ∝ V/L5; at higher diode voltages, J ∝ V2/L6.
Electrohydrostatic Problems for a Free Liquid Surface
Authors: Cade R.
Published: April 2005

Solutions are obtained of the equation which, with the assumption of axial symmetry, governs the form of a liquid surface in an electrostatic field, the liquid being electrically conducting in bulk and having a double layer at the surface. The problems concerned are ones in which, in the absence of an applied field, the surface would be a horizontal plane (a ``free surface''). Those of the line charge and point charge are basic and are solved in the first approximation. Extensions are made in three interwoven directions, solutions to the second approximation, more complicated given charge systems, and conductors (the cylinder and sphere). A complete second-approximation solution is obtained for the line-charge problem; partial solutions of this order are obtained for the cylinder and sphere problems and have the features one would want in practical applications of the results.
Collisional Mechanism for Producing Electron Cyclotron Echoes from Plasmas
Authors: Crawford F. W. , Harp R. S.
Published: April 2005

Recent experimental work has established that repeated pulsing, at the electron cyclotron frequency, of a plasma in a slightly inhomogeneous magnetic field results in the stimulation of echo trains. It has been recognized that the production mechanism for these echoes involves some nonlinear process, but those suggested and analyzed previously have not given results agreeing satisfactorily with experiment. In this paper, it is shown that if electron-neutral momentum transfer collisions are taken into account, a suitable nonlinear theory predicting both two-pulse and three-pulse echo characteristics can be developed. Computations based on this theory are presented, and agree well with the published experimental observations.
Role of Condensation Phenomena in the Measurement of Film Thickness by the Oscillating Quartz Crystal Method
Authors: Bakos J. , Nagy Gy. , Szigeti J.
Published: April 2005

The deposition of thin layers of ZnS and MgF2 on each other and on a glass surface was studied. The rate of evaporation, the film thickness, and the reflection of the layers were measured simultaneously. Condensation effects were found to influence the formation of layers on different substrates, a fact which has to be taken into account in measurements using the oscillating quartz crystal technique.
Effects of Stress-Induced Band-Gap Widening and Defects in GaAs Junctions
Authors: Rindner W. , Pittelli Ernest
Published: April 2005

The effect of compressive stress on band-gap widening and hence on the diffusion current in GaAs junctions is derived theoretically and verified experimentally. The presence of defects is shown to lead to current increase as opposed to a reversible decrease caused by the band-gap effect.
Effect of Sample Thickness and Operating Voltage on the Contrast of Kossel Transmission Photographs
Authors: Yakowitz H.
Published: April 2005

The photographic contrast of transmission Kossel patterns is examined in terms of the voltage and thickness variables since other parameters in the contrast equation generally cannot be controlled by the investigator; they are fixed functions of the material. It is shown that there is no single thickness yielding optimum contrast. However, manipulation of the contrast equation yields an approximation to the thickness and operating voltage relationship giving Kossel transmission photographs of nearly optimum contrast. Methods for calculating this relationship for any crystal-radiation combination are described. It is assumed throughout that the crystal is not completely free of imperfections; however, neither is the crystal assumed to be completely mosaic.
Electron Recombination in Laser-Produced Hydrogen Plasma
Authors: Litvak M. M. , Edwards David F.
Published: April 2005

Time-resolved spectroscopic measurements were made of the decay of a laser-produced discharge in hydrogen over a range of pressures from 1 to 70 atm. Stark widths and line-to-continuum intensity ratios yielded the electron density, and temperature time history, which indicated temperature decay because of radiation, and expansion cooling and electron loss because of collisional-radiative recombination, as verified by solutions obtained from the rate and energy equations.
Influence of Plasma-Tube-Surface Interaction on the Helium-Neon Laser Lifetime
Authors: Martinez J. V.
Published: April 2005

Results here presented indicate that the surface of a fused silica tube is decomposed as a result of bombardment by neon ions produced in an rf helium-neon laser discharge. The decomposition products are oxygen and a reduced form of silica. The concentration of oxygen released is sufficient to contaminate a helium-neon lase rmixture and prevent laser action. Evidence shows that in the preliminary stages of the decomposition E1′ centers are produced. The various stages in the erosion of the tube surface are shown by means of electron micrographs.
Saturation and Gain of Gas Lasers from Modulation Experiments
Authors: Bolwijn P. T.
Published: April 2005

It is shown theoretically that an analysis of single mode output power modulation, obtained via excitation density or via resonator Q modulation is a very sensitive method for studying both the unsaturated net gain and the saturation behavior of gas laser transitions. This theoretical description starts from the theory of Lamb.

Experiments with excitation density modulation in a 1.15 μ He–Ne laser are reported. The output power modulation as a function of the detuning of the resonator, which yields information on the saturation behavior, is found to agree partly with the theory if collision effects are taken into account. Deviations from the theory may be due to higher-order saturation terms, which is shown qualitatively by starting from the extended theory of Lamb, derived by Uehara and Shimoda. A detailed quantitative explanation of the observations at higher excitation levels awaits incorporation of collision effects in the higher-order saturation terms. The output power modulation as a function of modulation frequency may give information on the unsaturated net gain. In our case, however, the frequency response is determined by the long metastable lifetimes of He.
Anomalous Schottky Effect
Authors: Hansen Lorin K.
Published: April 2005

An analysis is presented of the effect of an electric field upon a ``patchy'' thermionic emitter. The model assumed for the analysis is that of parallel strips in a plane arranged with adjacent strips alternating between two particular values of work function. Calculations are made showing the dependence of emission on various parameters in the model. Some comparisons are made between the above analysis, the Nottingham strip theory for field effects, and experimental data presented by Nottingham. On the basis of the above analysis a simple model is presented for estimating the field effect on thermionic emission. Results from the simplified model are compared with those from the more detailed analysis.
Theory of the Infrared Generation by Coherently Driven Molecular Vibrations
Authors: De Martini Francesco
Published: April 2005

The problem of the generation of the coherent far ir radiation by a resonant parametric coupling between light waves is taken into consideration in the present paper. The equations of propagation of the interacting waves are given and the effect of the ir activity of the stimulated Raman active resonant mode on the dynamics of the wave interaction is considered. The experimental case of crystals and fluids as suitable media for achieving the effect is taken into account. At last, considerations on the resonant phase matching condition show that the achievement of the effect is not critical in general cases.
Effect of 60Co γ Rays on High-Resistivity p-Type Si
Authors: Djerassi H. , Merlo-Flores J. , Messier J.
Published: April 2005

Defects created by γ rays in high-resistivity (1000 to 10 000 Ω·cm) boron-doped silicon have been studied by Hall effect and resistivity measurements. Only one energy level is observed at 0.268 eV above the valence band by irradiation at 300°K. Its statistical weight is equal to ½. The defect annealing between 100° and 200°C occurs by the agency of another defect. In some special cases, a more complex association with a third defect can be observed, which introduces another level at 0.21 eV above the valence band. All the results obtained are compatible with the divacancy assuption. Furthermore, we observe, by irradiation at 77°K, the formation of unstable defects, which disappear at 170°K.
Analysis of Temperature Fluctuations in ac Heated Filaments
Authors: Holland Lawrence Rozier , Smith Richard C.
Published: April 2005

The temperature fluctuation in ac heated wires is studied, and expressions are given for the magnitude and phase of all harmonic components of the temperature. Radial and end effects are treated as perturbations on the solution for the long thin wire. It is shown that corrections to the usual expression for heating power may be required when the temperature coefficient of resistance is large, and that surface fluctuations may differ greatly from those in the interior.
Vacuum-Deposited Magnetic Thin Films of Fe3O4–B2O3 Mixtures
Authors: Hacskaylo Michael
Published: April 2005

Films of Fe3O4–B2O3, varying in starting compositions of 100% to 90% Fe3O4 mixed with 0% to 10% B2O3 proportionally by weight, were deposited from tungsten boats at a pressure of 2×10−5 Torr. It was found that the minimum B2O3 content was 5% for which films deposited from the mixture exhibited properties identifiable as those of magnetite. X-ray and electron-beam diffraction studies showed that films deposited from the 95–5 mixture and annealed in the vacuum to temperatures to 520°C were amorphous, but magnetite structure of increasing crystallinity was observed at higher annealing temperatures to 750°C. The optical reflection spectra of the annealed films in the 300- to 650-mμ region agree with the bulk spectra. For films deposited at substrate temperatures less than 300°C, a low-coercive magnetic switching dB/dt peak of 2.7 Oe was observed. A complex magnetic anisotropy was observed for the low coercive films. For films that were deposited and/or annealed at substrate temperatures greater than 300°C, the coercive fields were observed to be several orders of magnitude larger. The magnetic high coercivity has not been fully investigated.
Magnetic Decay in a Hollow Elliptic Cylinder. III
Authors: Weinstein M. A. , Stijovic Radomir
Published: April 2005

Earlier results for the relaxation time of an axial magnetic field in a conducting hollow elliptic cylinder are extended to the case of thick-walled cylinders of moderate eccentricity.
Surface Wave Instability in Helicon Wave Propagation. III. Theory of Multilayered Structures
Authors: Saunders L. M. , Baraff G. A.
Published: April 2005

The surface wave instability, investigated by Baraff and Buchsbaum for helicon propagation along a sandwich structure, is investigated here for a multilayered structure in which alternating layers of material carry a drift current which can transfer energy to the wave. The resulting growth rates agree with what would be predicted by using the analysis of the sandwich structure to calculate power transferred at each interface as though the others were not there and then summing the result over all interfaces.
Nanosecond-Pulse Microwave Breakdown in Air
Authors: Felsenthal Peter
Published: April 2005

Nanosecond-pulse microwave breakdown in air is derived by means of an improved technique. Breakdown data have been obtained by using dc pulse breakdown methods in a region where breakdown is controlled only by gas processes. The data so obtained show good agreement with properly modified microwave breakdown theory and, when plotted in terms of the same parameters, good agreement with previous normalized pulsed microwave results. Calculated results for microwave breakdown fields as a function of pulse length (10−9 to 10−7 sec), frequency (1 to 27 GHz), and air pressure (10−1 to 760 Torr) are given.
Lattice Parameter of Alpha Iron by Divergent Beam Diffraction
Authors: Pietrokowsky Paul
Published: April 2005

The divergent beam diffraction technique has been used to determine the lattice parameter of single crystals of alpha iron made by vapor deposition techniques. An electron beam focused to approximately 10 μ was used to produce a source of K series characteristic radiation within the samples. All unique Kossel conics which emerged from the specimens were recorded on flat photographic films. The back-reflection geometry was employed. Three different crystal orientations were investigated: a fourfold symmetry axis normal to the film plane, a threefold symmetry axis normal to the film plane, and mirror—mirror symmetry of the crystal normal to the plane of the film. Data obtained from the latter photographs have been used to demonstrate the application of the method of ratios. These analytical techniques were applied to Kossel conics that were continuous and interrupted. The lattice parameter was established by five different series of calculations. The most accurate value of the lattice parameter obtained in this investigation was 2860.6±0.1 xu. Stereographic projections have been made for three different orientations of bcc crystals. The value of the dimensionless parameter (λ/a) is 0.675 in these representations. All Kossel conic intersections required by symmetry considerations are indicated.
Hot Electron Energy Loss in Tunnel Cathode Structures
Authors: Handy Robert M.
Published: April 2005

A variety of scattering processes occur within the metal—oxide—metal tunnel cathode, with the result that most of the injected electrons fail to escape into vacuum. By considering the over-all behavior it is possible to identify the most important loss mechanisms and where they occur.

Electron emission measurements suggest that the internal hot electron velocity distribution in the exit metal films is isotropic as a result of numerous phonon scattering events. It is also found that the electron attenuation length in the exit metal film is not a strong function of energy over most of the observable range. As a direct consequence one obtains the result that the shape and mean energy of the emitted electron energy distribution are determined principally by the scattering in the oxide layer. Collision ionization is unlikely; hence optical phonon scattering is believed to be the principal oxide energy loss mechanism. If the scattering is random and independent of energy, both the mean energy loss (ΔE) and mean square deviation (δ2) should depend linearly on oxide thickness (x). Within the limits of the available data this is shown to be reasonably correct, and a mean rate of energy loss dE/dx≈0.03 eV/Å is obtained. This corresponds to about one optical phonon emission event for every 4-Å travel measured along the field direction. The consistency of the argument is tested by showing that δ2 also varies linearly with oxide thickness. The minimum ingredients for a model of the hot electron scattering processes are outlined.
The Wiedemann—Franz Ratio of Metallic Uranium at Elevated Temperatures
Authors: Erez Gidon , Even Uzy
Published: April 2005

The electric resistivity, heat capacity, and temperature diffusivity of uranium at temperatures from 50°-800°C were measured on the same sample. The Wiedemann—Franz ratio was then calculated. A transition seems to occur at 250°C.
Angular Distribution of Radiation Scattered Coherently by a Plasma Cylinder
Authors: Jones A. R. , Wooding E. R.
Published: April 2005

The intensity and phase of a wave scattered by a cylindrical plasma column have been computed for the case where R/λf is near unity. The angular distribution of intensity was measured when a 9.6-GHz plane wave was incident on a plasma of 2.68-cm radius with the electric vector parallel to the cylinder axis. The variation of phase with angular position was also determined. A resonance was observed.
Crystallography of SiP and SiAs Single Crystals and of SiP Precipitates in Si
Authors: Beck C. G. , Stickler R.
Published: April 2005

Transmission electron microscope examinations of silicon single crystals, phosphorus-diffused at low temperatures from anodic oxide films as phosphorus sources, showed the presence of crystallographically oriented precipitate. X-ray and electron diffraction investigations of SiP and SiAs single crystals prepared by a vapor-growth method revealed the orthorhombic crystal structure of the as-grown compounds. Using these structure data, the precipitate in the diffused silicon could be identified by electron diffraction as SiP. The orientation relationship SiP-precipitate/Si-matrix was determined.
Oriented Growth of Semiconductors. III. Growth of Gallium Arsenide on Germanium
Authors: Bobb L. C. , Holloway H. , Maxwell K. H. , Zimmerman E.
Published: April 2005

Gallium arsenide has been grown on germanium using arsenic trichloride and gallium. With optimum growth conditions the epitaxial layers have properties close to those of good-quality bulk crystals. Comparison between epitaxial and bulk crystals is made in terms of the widths of the x-ray rocking curves and of the properties of p-n junctions formed within the epitaxial layer.
Oriented Growth of Semiconductors. IV. Vacuum Deposition of Epitaxial Indium Antimonide
Authors: Holloway H. , Richards J. L. , Bobb L. C. , Perry J. , Zimmerman E.
Published: April 2005

Using flash vaporization, indium antimonide has been grown epitaxially on indium antimonide substrates. The perfection of the epitaxial layers depends critically upon the method used for preparation of the substrate surface. Best results were obtained after the substrates had been ion-bombarded and annealed. Layers grown under optimum conditions yield x-ray rocking curves similar to those from good bulk crystals. p-n junctions made within these layers have characteristics similar to those reported for high-quality diodes made with bulk indium antimonide.