bluuebunny/crossref_metadata_2025 huggingface dataset:
Correlation Theorem for Nonstationary Complex Stochastic Processes of a Real Variable
Authors: Kouskoulas Vasilios
Published: February 2004

The object of this paper is to derive a general correlation theorem for a class of complex stochastic processes of a real argument. By means of this theorem, the correlation functions and the time-power spectral densities, which are defined by averaging the realizations of the processes and their running spectra, respectively, are related to each other by a pair of one-dimensional integral transformations. This theorem is reduced to corresponding theorems for other classes of stochastic processes which form subsets of the set of processes under consideration. The properties of the correlation functions and time-power spectral densities along with questions concerning conditions for the existence and usefulness of these concepts in scientific and engineering applications occupy a good portion of this paper.
Tellurite Glass: A New Acousto-Optic Material
Authors: Yano T. , Fukumoto A. , Watanabe A.
Published: February 2004

A new glass, composed of TeO2, was found to be well suited to acousto-optical devices. It exhibits a high figure of merit: Me(p2n6/ρv3) = 23.9×10−18 sec3/g and has very good optical qualities with regard to visible light.
Pressure Dependence of Infrared Eigenfrequencies of KI, RbI, and Their Mixed Crystals
Authors: Ferraro J. R. , Mitra S. S. , Quattrochi A.
Published: February 2004

The pressure dependence of the long-wavelength transverse-optic-phonon frequency of KI and RbI was determined by infrared transmission measurements. The mode Grüneisen parameters thus obtained compared well with those calculated from a rigid ion model using Born-Mayer-type potentials. The phase transition to CsCl structure at appropriate pressures was noted for both crystals, accompanied by a lowering of the k lim →≃0 TO phonon frequency. Infrared transmission measurement and its pressure dependence confirms that the mixed-crystal system K1−xRbxI forms an intermediate class of mixed-crystal system ``half-way'' between the ``two-mode''- and ``one-mode''-type mixed crystals.
X-Ray Diffraction Investigation of β′-NiAl Alloys
Authors: Hughes T. , Lautenschlager E. P. , Cohen J. B. , Brittain J. O.
Published: February 2004

An x-ray diffraction investigation of the structure of β′-NiAl alloys was conducted to define the state of order, identify the lattice sites occupied by compositional vacancies, and measure both static and vibrational components of atomic displacements, all as functions of temperature and composition. Long-range order was found to be virtually complete up to 1000 °C and remained substantial up to the melting points of the alloys. Compositional vacancies present in Al-rich β′ alloys were found to occupy Ni lattice sites only, at least to 1000 °C. Static atomic displacements were minimal at stoichiometry, increased with initial Ni or Al additions, and then decreased with further Ni or Al additions, with the maximum displacement about midway between stoichiometry and the β′ phase boundaries. Vibrational atomic displacements were also minimal at stoichiometry, but in contrast to static displacements, increased continually as either Ni or Al was added. Atomic displacements were correlated with known mechanical properties of β′-NiAl alloys.
Theory of Dislocation Cells. III. Simple Cells Constructable from Multipoles
Authors: Moore J. T. , Kuhlmann-Wilsdorf D.
Published: February 2004

Infinitely tall dislocation cells such as may be constructed from assemblies of similar dislocation multipoles are investigated. The long-range stress fields of these are shown to be the same as those of the corresponding dislocation multipoles, while the short-range stress fields are those of the corresponding infinitely extended tilt walls, except for disturbances in the immediate vicinity of corners. It is shown that the stresses of a cell of given shape, cross-sectional area, and angle of relative misorientation, decrease in magnitude the more closely the dislocations in its walls are spaced. In the limit of continuous dislocation distributions all cell stresses vanish identically. Terminated cells are briefly considered, and a method for the simple construction of two-grid tilt boundaries, composed of parallel edge dislocations involving two arbitrarily oriented Burgers vectors, is presented.
A Consideration of Poole-Frenkel Effect on Electric Conduction in Insulators
Authors: Ieda Masayuki , Sawa Goro , Kato Sousuke
Published: February 2004

The extended Poole-Frenkel model presented here includes the variation of the barrier height with electric field in directions both opposite and forward to the electric force on an electron. The equation for the voltage-current characteristics based on this model gives not only the usual Poole-Frenkel equation at extremely high electric fields but also Ohm's law at low fields. Several published experimental data are in good agreement with this equation.
Gallium Diffusions into Silicon and Boron-Doped Silicon
Authors: Makris J. S. , Masters B. J.
Published: February 2004

Radiochemical techniques were used to measure the 72Ga distribution profiles resulting from gallium diffusions into intrinsic silicon and into boron-prediffused extrinsic silicon. Gallium diffusions were conducted from 900 to 1050 °C. Gallium diffusivity in intrinsic silicon is found to be well described by the expression Dint =60 exp(−3.89 eV/kT) cm2/sec and in heavily boron-doped extrinsic silicon by the relation Dext ≃ 0.008(−2.49eV/kT) cm2/sec. The observed increase in Ga diffusivity with hole concentration is explained by means of a generalized monovacancy diffusion model, in which the diffusion of ionized substitutional impurities in silicon is assumed to be controlled primarily by the concentration vacancies of the opposite charge type.
Transition from the Primary Streamer to the Arc in Positive Point-to-Plane Corona
Authors: Suzuki Toshio
Published: February 2004

This paper reports for the first time measurements with multiple techniques delineating the complete sequence of events from the primary streamer to the thermalization of a highly ionized channel to the arc phase in the common spark transition for relatively small point-to-plane gaps. The observations cover a range of point diameters from 0.1 to 2 mm, for gaps in room air from 1 to 4 cm long, covering the whole range of potentials from streamer onset to in excess of 30% above the standard sparking threshold. It is shown that starting with the primary streamer, which occasionally at its start creates photoionization up to the midgap and at the cathode, there is produced a succession of ionizing waves of potential starting in many cases on the arrival of its tip at the cathode. These waves, observed by photomultipliers as well as by current pulses over a period of some microseconds, create what has been called a ``secondary streamer'' by Hudson and Loeb. Unless overvoltage exceeds 30%, the electron density and temperature in the resulting channel are not adequate to thermalize to an arc. Above this value, thermalization occurs in several hundred nanoseconds. At lower overvoltages, there is a dark phase lasting at low values for hundreds of microseconds. During the dark phase, there is a virtually nonluminous current involving ion motion. This regenerates the anode point field and leads to a series of one or more very heavy, very fast, luminous ionizing-potential waves. The higher the overvoltage, the fewer the number of these pulses spaced in time on ion movement scales. After the last pulse the thermalization follows through gas heating time from 40 to 60 nsec.
Recovery of Deformed Polymers. II. Repeated Cold Drawing of Polycarbonate, Polyethylene, and Polypropylene
Authors: Uhlmann D. R. , Park J. B.
Published: February 2004

Studies of repeated cold drawing with intermediate annealing have been carried out on three polymers: polycarbonate, polyethylene, and polypropylene. In the case of polycarbonate, samples recovered to their original lengths in the anneals. On testing, necking and yielding behavior were observed on all draws, with the modulus and yield stress dropping most significantly between the first and second draws, and by a smaller amount between the second and subsequent draws. The recovery kinetics are complex; activation energy spectra derived from these kinetics are centered about 22.5–24.5 kcal/mole, and do not vary significantly with the initial strain or number of the draw. In the case of polypropylene, yielding and necking were observed on all draws after annealing at 160°C; with annealing at lower temperatures, yielding was noted on only the first draw. For both polyethylene (PE) and polypropylene (PP) incomplete recovery was observed on the intermediate anneals; the elastic modulus and drawing stress were significantly smaller on the second draw than on the first draw, and were effectively unchanged between the second and subsequent draws. This softening effect decreased with increased extent of recovery in the intermediate anneal. Activation energy spectra derived from the recovery kinetics were centered about 14.5–15.5 kcal/mole for PP and 22–23 kcal/mole for PE; the occurrence of recovery processes having significantly lower activation energies is also indicated.
Multiphonon Orbit-Lattice Relaxation and Quantum Efficiency of 10-μ Infrared Quantum-Counter Upconversion in Rare-Earth-Doped Crystals
Authors: Wright John C. , Fong Francis K. , Miller Marvin M.
Published: February 2004

Various quantum counter schemes involving the lower J levels of Eu3+ and Sm2+ are examined in terms of orbit-lattice-induced multiphonon relaxation processes. The quantum efficiency of the upconversion process has been quantitatively evaluated as a function of the laser pump which brings about the frequency upconversion. Optimum conditions are given for the 10-μ infrared quantum counter, and its detectivity and response time are discussed and compared with other representative 10-μ detectors. It is shown that the 10-μ quantum counter can be operated at 77 K.
Thermal Stability of Polymethine Q-Switch Solutions
Authors: Pastor R. C. , Kimura H. , Soffer B. H.
Published: February 2004

The reversible and irreversible thermal bleaching of two solutions widely used for Q switching at 1.06 μm were studied. Over the temperature range studied, three first-order reaction paths were necessary and sufficient to describe the experimental results. The two dyes were shown to exhibit significantly different rate constants.
Measurement and Interpretation of Dynamic Spectrograms of Picosecond Light Pulses
Authors: Treacy E. B.
Published: February 2004

A dynamic spectrogram depicts intensity as a function of frequency and time simultaneously, subject to the classical uncertainty relation δωδt≈2π. For an optical pulse having the Fourier transform |g(ω)|eiφ(ω), high-resolution spectroscopy gives |g(ω)|2, while the dynamic spectrogram gives knowledge of ∂φ(ω)/∂ω permitting reconstruction of many features of the amplitude and phase modulations of the original pulse. Linear, parabolic, and two sinusoidal spectrogram shapes are interpreted theoretically. An instrument for measuring dynamic spectrograms is described. It involves the use of a spectrometer with ultrafast time response and has been used in an antisymmetric mode to measure frequency sweep rate as a function of wavelength for picosecond laser pulses. The change in the dynamic spectrogram of a pulse brought about by linear pulse compression and the resultant change in pulse envelope shape have been computed for a typical picosecond pulse.
Impedance Matching a Josephson Galvanometer by Means of a Superconducting Transformer
Authors: Clarke John , Tennant William E. , Woody D.
Published: February 2004

The concept of an effective noise temperature is developed and applied to superconducting galvanometers. It is shown that even when the device is being used at a temperature above its noise temperature, Johnson noise in a source resistance may be observed only if this resistance is below a certain value, defined as the critical resistance. A detailed design is given for a superconducting transformer which matches the galvanometer to higher resistance and thereby appreciably increases the critical resistance. The transformer may be used at zero frequency. A practical transformer is described which has been used with the Josephson device known as the Slug. The transformer increased the critical resistance from 7×10−8 to 2×10−2 Ω and could be readily adapted to match to resistances up to 1 Ω.
Transient Signals from a Buried Magnetic Dipole
Authors: Wait James R. , Hill David A.
Published: February 2004

The solution for a pulse-excited magnetic dipole is carried through for a conducting half-space model of the earth. All displacement currents are neglected so the solution is not valid at very small times in the transient response. It is shown that the waveforms of the magnetic field components on the surface depend both on the conductivity of the earth and the geometrical parameters of the problem. The results have possible application to electromagnetic signaling and direction finding for a buried source.
Impurity Photoconductivity and Impact Ionization of Shallow States in Semiconductors
Authors: Crandall Richard S.
Published: February 2004

A model calculation is made of the photocarrier density in a semiconductor that is undergoing impact ionization of shallow impurity states at low temperatures. The following conclusions are drawn about the photocarrier multiplication. If there is no dependence of the impact-ionization probability on the carrier density, then an uncompensated material shows little if any multiplication. A compensated sample on the other hand can show large multiplication. If the impact-ionization probability does depend on carrier density, then both compensated and uncompensated materials can show multiplication. This will be the case if the impact ionization probability increases with increasing carrier density. If it decreases with increasing carrier density then multiplication is reduced. The effects of photoexcitation on a current-controlled negative resistance is also discussed. The theory is compared with experimental results on n-type CdS, GaAs, and CdSe. In all cases, the model can explain the absence or presence of multiplication.
Transition from Transient to Steady-State Currents in Insulators
Authors: Mort J. , Scher H.
Published: February 2004

An essentially descriptive treatment is presented of the transition from transient to steady-state currents for small, i.e., space-charge unperturbed signals. This transition has not previously been discussed in the literature. The analogous transition for large signals, i.e., space-charge perturbed and ultimately space-charge limited, is discussed in a comparative framework. The theoretical predictions are illustrated by new results on electron transport in orthorhombic sulfur single crystals. The low drift mobility and long lifetime for electrons in this elemental insulator allowed, for the first time, the observation of the time-resolved transition from transient to steady-state currents for small signals. The experimental results provide the first direct experimental observation that space-charge-perturbed currents, as opposed to space-charge-limited currents, are bulk limited even when light intensity dependent.
Stopping Cross Sections for 0.3- to 1.7-MeV Helium Ions in Silicon and Silicon Dioxide
Authors: Thompson D. A. , Mackintosh W. D.
Published: February 2004

Stopping cross sections of helium ions with energy 0.3–1.7 MeV have been measured with a systematic error of ±1.6% in silicon and ±1.3% in amorphous silicon dioxide. The probable random error of the measurements is estimated to be 2.3%. Experimentally, a backscattering technique is used in which the ions are scattered through 150° from a heavy mass atom on the back surface of the target film. The stopping cross-section data were obtained using a 1114-Å-thick silicon target film and a 1030-Å silicon dioxide film. The results for SiO2 indicate a deviation from the Bragg-Kleeman rule of additivity of atomic stopping cross sections.
Investigation of Te-Doped GaAs Annealing Effects by Optical- and Channeling-Effect Measurements
Authors: Mitchell I. V. , Mayer J. W. , Kung J. K. , Spitzer W. G.
Published: February 2004

Backscattering and channeling-effect measurements with 2.5-MeV helium ions and measurements of the position of the infrared reflectivity plasma edge were used to investigate the absolute concentration of Te, the percentage of Te on lattice sites, and the free-carrier concentration in GaAs doped with [Te] ≈ 1019 cm−3 as a function of anneal. A 700°C anneal produced a reduction in carrier concentration [ne] by 20±2% (from the preanneal value of 5×1018 cm−3), and in the fraction of Te atoms on lattice sites. After an anneal at 1100°C, followed by quenching, [ne] rose to 7×1018 cm−3 while the Te distribution reverted to the original highly substitutional form. Throughout the experiment no measurable change from [Te]=9×1018 cm−3 was found. The correlations are discussed and related to existing models for anneal-dependent complexes.
Influence of the Incomplete Ionization of Impurities on the Capacitance of p-n Junctions
Authors: Nuyts W. , Van Overstraeten R.
Published: February 2004

A method is described for calculating the capacitance of p-n junctions, taking into account the incomplete ionization. Degeneration is neglected. A simple approximate formula is derived for symmetrical abrupt junctions. Numerical calculations show that, for linearly graded junctions, the slope of the C−3-vs-U plot is not changed but that the intercept with the U axis is smaller than the classical value derived on the assumption of complete ionization.
Schottky-Barrier Anomalies and Interface States
Authors: Levine Jules D.
Published: February 2004

The surface-state energy distribution at the metal-semiconductor interface of a Schottky barrier has been deduced by combining a general theoretical analysis with one observed fact concerning the anomalous temperature dependence of the forward current on voltage. The fact, empirically found by Saxena, Padovani, and Sumner and by Padovani, is that the exponential terms of the forward-current characteristic involve the sum of T plus T0. Here T is the absolute temperature and T0 is the empirical parameter which is essentially independent of temperature at constant current. This fact leads to the following new theoretical conclusions: (i) The surface-state energy distribution near the Fermi level is a simple exponential with a characteristic e-fold energy increase E0 that can be computed from T0. (ii) A plot of T0−1 vs voltage V yields essentially a straight line whose slope and intercept can be used to compute E0 and the barrier height φB. (iii) In reverse bias, φB varies as the log of the surface electric field F, and E0 can be computed from the slope. (iv) Finally, the log of the reverse current is proportional to (E0/kT)log F. These theoretical predictions have been substantially checked, and E0 deduced from data on the following diverse Schottky barriers: Au/GaAs, Cr/Si, Ag/ZnS, Zu/SrTiO3, and ZrSi2/Si, as measured by Padovani and Sumner, Padovani, Saxena, Wronski, Carnes and Goodman, and Andrews and Lepselter. Furthermore, the forward- and reverse-current temperature anomalies observed by Padovani on the same sample of Au/GaAs lead to the same value of E0, E0=0.045±0.005 eV. Also, φB as obtained from a plot of T0−1 vs V on diverse Schottky barriers agrees closely with φB as obtained from independent methods. These features demonstrate a measure of self-consistency in the theory. A derivation of the empirical equation involving T0 is given and its limits of applicability are stressed.
Continuous Coherent Microwave Oscillation from n InSb
Authors: Tacano Munecazu , Kataoka Shoei
Published: February 2004

Continuous coherent oscillation from nInSb at 77°K under transverse magnetic field is investigated experimentally. The oscillation frequency is measured in detail as a function of the magnetic field together with the threshold relation between the magnetic field and the current. Interpretation is made in terms of the helical-mode instability both on the threshold and in the growing-wave conditions assuming the formation of a microplasma filament.
Microwave Measurement of the Velocity—Electric-Field Characteristic of Inhomogeneous Epitaxial GaAs with Conducting Substrate
Authors: Glover G. H.
Published: February 2004

The velocity—electric-field (v-E) characteristic of n-type GaAs measured by microwave techniques corresponds to the intrinsic material characteristic only when the sample is uniform. This paper presents a theoretical and experimental investigation of the measured v-E characteristic for epitaxial samples with nonuniform doping concentration. The theory predicts substantial degradation of apparent peak-to-valley ratio and negative differential mobility from intrinsic values, as well as a decrease in apparent critical field for nonuniform material. The measurements are in good agreement with theory, and show a measured peak-to-valley ratio of 2.0 for uniform GaAs, decreasing to 1.5 for material with a linear doping gradient (1.5≤n≤2.5)×1015 cm−3 across the 11-μ-thick layer. Values as low as 1.2 were observed for samples with a localized high-resistance region. The measurements were obtained by a 35-GHz microwave heating method which permitted convenient characterization of practical device material with conducting substrate. The v-E data were corrected for high-frequency effects arising from energy relaxation. The results indicate that much of the divergence in reported v-E characteristics can be explained on the basis of sample inhomogeneity.
Crystallographic Orientations and Interfacial Mismatches of Single-Crystal CdS Films Deposited on Various Faces of Zinc-Blende-Type Materials
Authors: Igarashi Osamu
Published: February 2004

Single-crystal CdS (wurtzite-type) layers were prepared by vapor growth technique on the (001), (110), (112), and (221) faces of zinc-blende-type crystals such as GaP, GaAs, InAs, and CdTe in hydrogen atmosphere. Deposition temperatures were ranging from 620 to 740°C. The layer thicknesses were up to 20 μm. Relations of crystallographic orientation between the grown layers of CdS and the substrates were studied. It was found that (1) the [0001] a axis of CdS was nearly parallel to the [111] a axis of the substrate and (2) the (112̄0) face of CdS deposited on the faces except for (112) was parallel to the (11̄0) face of the substrate, and the (112̄0) face of CdS deposited on the (112) face was not always parallel to the (11̄0) face. Angles between the [0001] a and [111] a axes were a few degrees (up to 3°) and they depended both on substrate materials and orientations of the substrate surfaces. The dislocation model of small-angle grain boundaries was applied to interpret the result. It was found that CdS crystals are grown on crystallographic planes of zinc-blende-type materials in such a way that the interfacial mismatch between close-packed planes of CdS and the substrates vanishes.
Measurement and Calculation of Absolute X-Ray Intensities
Authors: Brown D. B. , Gilfrich J. V.
Published: February 2004

Measurements of the absolute intensity of Kα and Lα x-ray characteristic lines from x-ray tubes have been compared with values predicted by an electron-transport calculation. Agreement is within 6% for Kα lines and 35% for Lα lines, when the ionization cross sections used in the calculation are taken from Burhop, modified as has been suggested by Green and others.
The Variation of Vaporization Rates with Orientation for Basal Planes of Zinc Oxide and Cadmium Sulfide
Authors: Leonard Ralph B. , Searcy Alan W.
Published: February 2004

The metal (0001) basal faces of hexagonal (wurtzite) modifications of both zinc oxide and cadmium sulfide are shown to vaporize at higher rates than the nonmetal (0001̄) faces. The difference in rates has been measured for cadmium sulfide as a function of temperature. Surface morphologies also differ between opposite basal faces of both kinds of crystals. The data suggest that desorption may be rate limiting.
Effect of Substrate Bias on Tantalum Films Sputtered in an Oxygen-Argon Mixture
Authors: Westwood W. D. , Wilcox P. S.
Published: February 2004

Tantalum films have been deposited on biased glass and ceramic substrates by dc sputtering in an oxygen-argon mixture The resistivity of the films was approximately 800 μΩ cm when the substrate bias was zero, but decreased when either positive or negative potential was applied to the substrate. Resistivities of approximately 200 μΩ cm were obtained by applying +100 and −100 V, and resistivities as low as 50 μΩ cm were obtained at a substrate bias of −200 V. The oxygen content of the films, measured by an anodization technique, was approximately 35 at.% on unbiased substrates but decreased with substrate bias. While films deposited at −100 V bias contained approximately 10 at.% oxygen, only half of this amount was present in those deposited at +100 V. The reduction in oxygen content, and thus in resistivity, can be explained by a combination of two effects. For positive and low negative bias, increased gettering due to enhanced sputtering rate is most important, but for higher negative bias, removal of oxygen by argon-ion sputtering is also important.
Temperature Changes in Thin Films during Growth by Physical Vapor Deposition. II. Experimental
Authors: Thornburg D. D. , Wayman C. M.
Published: February 2004

Empirical confirmation of a theory of temperature changes in thin films during growth has been obtained by measurement of the radiant heat flux at the substrate by calorimetry, of the evaporant flux with a quartz crystal monitor, and of the film temperature per se with a Ag–Bi thin-film thermocouple. In particular, it is shown that the degree of substrate bonding to an isothermal reservoir plays a very important role in determining film temperature. A transition temperature exists below which radiant losses from the source are the predominant supply of heat and above which impingement and condensation of the evaporant provide the greatest supply of heat.
Measurement of Time-Averaged Voids by Neutron Diagnosis
Authors: Harms A. A. , Lo S. , Hancox W. T.
Published: February 2004

Neutron diagnostic considerations have been applied to the determination of void fraction in hydrogeneous media. It has been found that, with the aid of specific definitions for certain neutron-transport parameters, neutron diagnosis offers a greater range of applicability and yields more accurate results than can be obtained by alternative detection techniques.
Comments on ``Transition from Ohmic to Space-Charge-Limited Conduction''
Authors: Queisser H. J.
Published: February 2004

In a recent note, Goronkin treats the problem of Ohmic vs space-charge-limited currents in high-resistivity semiconductor materials. He arrives at the conclusion ``that it is possible to select a material that will carry only space-charge-limited current when it conducts at all''. For GaAs, this condition should hold for a doping n < 2×1010 electron/cm3. This assertion would be significant for proposed nonlinear devices operating at very low voltages, such as 5 mV, predicted by Goronkin. The assertion pertains also to a new régime of semiconductor behavior, termed ``relaxation case'' by van Roosbroeck and Casey, who find a range of linear current/voltage relation up to 10 V in GaAs with only 5 × 107 electron/cm3. This note shows that Goronkin's paper contains errors of many orders of magnitude and that his results are invalid.
Effect of Nonmagnetic Inclusions on the Spin-Wave Linewidth in Polycrystalline YIG
Authors: Scotter D. G.
Published: February 2004

Nonmagnetic second-phase inclusions of two different average sizes (2.5 ± 0.5 and 1.2 ± 0.5 μ m) were produced in specimens of polycrystalline YIG. A dependence of spin-wave linewidth on inclusion size was observed. The linear relationship between spin-wave linewidth and the concentration of second-phase inclusions was dependent on the wave vector k. At k ≈ 2 × 105 cm−1, the relationship was 0.15 Oe and 0.075 Oe per % second-phase concentration for the samples with the smaller and larger inclusions, respectively. It is suggested that in porous specimens the average size of the pores may affect the spin-wave linewidth and that this effect is similar to the transit-time effect produced by finite grain sizes.
Fictitious Background Doping Effect on Diffusion in Silicon
Authors: Hu S. M.
Published: February 2004

In this note we suggest an explanation for the widely reported phenomenon of the background doping effect on impurity diffusion in silicon. We also present the relationship between the background doping and what may be called the fictitious surface concentration as well as what may be called the fictitious diffusivity.
Eddy Currents in Finite Conducting Sheets
Authors: Davis L. C. , Reitz John R.
Published: February 2004

This paper deals with eddy currents in bounded plane conductors. Specifically, we are concerned with the semi-infinite plane sheet and a conducting disk. The eddy-current distribution in a perfectly conducting sheet or disk due to a magnetic monopole source is obtained by a technique due to Sommerfeld. Sommerfeld's analysis for the disk is incomplete, but we have completed the derivation for this geometry. The eddy-current decay in a semi-infinite sheet of finite conductivity is solved by an approximate technique. The results are used to calculate lift, drag, and transverse forces on a magnetic monopole moving parallel to the edge of a semi-infinite sheet of finite conductivity.
First-Order Theory of Electrical Focusing in Cyclotron-Type Two-Dimensional Lenses with Static and Time-Varying Potentials
Authors: Reiser Martin
Published: February 2004

The potential distribution in cyclotron-type gaps with liner (outer electrodes at ground potential) is determined via Schwarz-Christoffel transformation, as well as by computer analysis (relaxation method). First-order focusing formulas for both static, as well as time-varying, potentials are derived. In addition exact calculations were carried out by direct numerical integration of the equations of motion with a computer program. The numerical data permitted an accurate evaluation of the validity of the analytical approximation, as well as further improvement of the theoretical formulas. Focusing relations are presented in a generalized form which shows the scaling laws and is readily applicable to different types of particles, energies, or lens geometries. As an example, the theory is applied to the axial motion of ions in a cyclotron.
Dependence of Second-Harmonic-Generation Coefficients of LiNbO3 on Melt Composition
Authors: Miller Robert C. , Nordland William A. , Bridenbaugh Paul M.
Published: February 2004

The three nonlinear coefficients d31, d22, and d33 that describe optical second-harmonic generation with LiNbO3 have been determined for crystals pulled from melts with Li/Nb atom ratios, (Li/Nb)m, of 0. 852, 0. 946, and 1. 083. The coefficients d22 and d33 were found to be insensitive to the melt composition whereas d31 increased by about 50% as (Li/Nb)m was increased from 0. 852 to 1. 083. These results suggest a marked Curie temperature dependence of the difference between the two Nb–O bond nonlinearities that give rise to the d's for LiNbO3.
High-Pressure Phase Transition and Demagnetization in Shock Compressed Fe–Mn Alloys
Authors: Christou Aristos , Brown Norman
Published: February 2004

Shock deformation of Fe–Mn alloys up to 14 wt% Mn results in a shock-induced phase transformation. It has been shown that bcc martensite with manganese in the range 4–16 wt% transforms to a stable close-packed phase under pressure without the occurrence of reversion. The addition of manganese to iron also decreases the transition pressure from 133 kbar for pure Fe to less than 70 kbar for Fe–14Mn. X-ray diffraction, electron-probe microanalysis, electron microscopy, and density results indicate that for the Fe–4Mn and Fe–7Mn alloys, the fcc phase has been stabilized after shock deformation, while the ε phase has been stabilized for the Fe–14Mn alloy. Saturation magnetization studies have detected a residual reduction in magnetization due to the retainment of the high-pressure phase.
Simultaneous Viscous Flow and Diffusion of Gases through Small Apertures
Authors: Pasternak R. A. , Christensen M. V.
Published: February 2004

A simple model for simultaneous viscous flow and diffusion of gases through small apertures has been formulated. Data obtained with a fine capillary and with a pinhole are in good agreement with the theoretical predictions. The experimental approach involving continuous flow of test and carrier gas past either side of the aperture is useful for the determination of the sensitivity of trace gas detectors.
Method for the Solution of Electromagnetic Scattering Problems for Inhomogeneous Dielectrics as a Power Series in the Ratio (Dimension of Scatterer) /Wavelength
Authors: von Roos Oldwig
Published: February 2004

In this paper the definitive work of Stevenson for the Rayleigh series expansion of electromagnetic scattering from homogeneous scatterers is extended to inhomogeneous scatterers. Furthermore, it is shown that a determination of the strength of the multipoles induced by the incident radiation is sufficient to determine the far field and therefore the scattering cross section, without relying on an awkward expansion and subsequent matching of far and near fields. The calculations are thus enormously simplified.
Optical Properties of Some Silicone Diffusion-Pump Oils in the Vacuum Ultraviolet—Using a Closed-Cell Technique
Authors: Sowers B. L. , Williams M. W. , Hamm R. N. , Arakawa E. T.
Published: February 2004

The optical properties of Dow Corning-704 and -705 diffusion-pump oils have been measured from 2→10.6 eV using a closed-cell technique. The data are interpreted in terms of molecular excitations of π, σ, and nonbonding electrons in the complex pump oil molecules and in terms of collective oscillations of electrons in the liquids. The optical constants of Dow Corning-200, another silicone oil, and liquid benzene from 2→10.6 eV are also presented for use in the interpretation of the pump oil data.
Effect of Growth Parameters on the Residual Stress and Dislocation Density of Czochralski-Grown Silicon Crystals
Authors: DeNicola R. O. , Tauber R. N.
Published: February 2004

This paper discusses the effects of pull rate and rotation rate on the dislocation density and residual stress distributions in Czochralski-grown silicon crystals. A photoelastic technique was used to study the residual stress. It was found that a pull rate of 7. 62 cm/h and a rotation rate of 12 rpm yielded a nearly ideal radial stress pattern and a relatively low and constant distribution of dislocations. In general, when the dislocation density increases from the center to the periphery, and the crystal has not undergone extensive plastic flow, an optical pattern indicative of a radial stress distribution is observed. Conversely, crystals which exhibit dislocation distributions that decrease toward the periphery and have undergone plastic flow show an optical pattern which indicates a departure from a radial stress.
Etch Pits at Dislocations in Nickel
Authors: Akhtar A. , Teghtsoonian E.
Published: February 2004

A technique has been developed of revealing both grown-in and glide dislocations in nickel by etching any arbitrarily chosen crystal plane. The success of the method does not depend on decoration of dislocations and hence can be applied to the study of deformed structures without the necessity for a heat treatment. The geometric features of the etch pits are reported and their relationships to the crystallographic directions and planes of Ni are discussed. Bend tests showed a satisfactory agreement between calculated and measured dislocation densities. The etch has been employed to reveal dislocation distribution in as-grown, annealed, and deformed crystals.
Changes in the Work Function of Iron in the α⇌γ Transformation Region
Authors: Hill R. V. , Stefanakos E. K. , Tinder R. F.
Published: February 2004

The work function of a polycrystalline iron filament changes somewhat abruptly in the α⇄γ transformation region. This change has been calculated from both electron-emission and positive-ion-emission experimental data. From the electron-emission results the difference φγ − φα is about 0. 09 eV, while from the positive-ion-emission results this difference is about 0. 06 eV.
Evidence for Partial Surface Spin Pinning in Ferromagnetic Resonance
Authors: Bajorek C. H. , Wilts C. H.
Published: February 2004

Spin-wave-resonance measurements of 81%-Ni–19%-Fe evaporated films 30–9000 Å thick at frequencies from 1 to 8 GHz, at room temperature and with the static magnetic field parallel and perpendicular to the film have been performed. The resonance spectra of both geometries are for the first time uniquely explained by the excitation of partially pinned spin-wave modes with A=(1.03±0.05)×10−6 erg/cm. The resonance fields for both cases are thickness dependent and consistent with a thickness-dependent demagnetizing field caused by film surface roughness.
Statistical Metallurgical Model for Electromigration Failure in Aluminum Thin-Film Conductors
Authors: Attardo M. J. , Rutledge R. , Jack R. C.
Published: February 2004

A statistical metallurgical model of the random structural defects which cause electromigration failure in aluminum thin-film conductors is presented. The model relates time-to-failure to the various divergences which may be present in the conductor. Structural divergences due to differences in grain size, grain-boundary mobility, and grain-boundary orientation with respect to the electric field vector E lim →, are considered. The statistical distributions of divergences due to these attributes are empirically determined. A computer is then used to simulate both the structure of a thin-film conductor and its time-to-failure. The simulation model is used to predict the dependence of conductor reliability on such microscopic design features as grain size distribution, conductor length, and conductor width. The curves produced by computer simulation are then compared with those derived from experimental data.
High Resistivity of dc-Sputtered Metal Films
Authors: Lee William W. Y.
Published: February 2004

Tungsten films were sputtered at 1.5-kV cathode voltage under various sputtering conditions. It was found that their resistivities differ greatly, ranging from 5×103 μΩ. The higher-resistance case corresponds to films deposited in the diode mode at 50-μ argon pressure, and the lower to films deposited in the triode made at 2-μ pressure. The higher-resistivity tungsten films have properties similar to the so-called ``low-density tantalum'' and a host of other metal films which have been prepared under similar sputtering conditions. Analysis by rf spark-source mass spectroscopy and electron microscopy support the theory that the high resistivity was caused by the incorporation of residual gases during the growth process.
Room-Temperature Recrystallization in Thick Bias-Sputtered Copper Deposits
Authors: Patten J. W. , McClanahan E. D. , Johnston J. W.
Published: February 2004

Deposits of copper up to 1 mm thick were formed at room temperature in a triode sputtering apparatus using a krypton discharge under various conditions of sputtering rate, gas purity, and substrate bias. Room-temperature recrystallization and grain growth displaying no twins were observed within 9 h after removal from the sputtering apparatus. This resulted in a dominant orientation of {100} planes parallel to the substrate-deposit interface. Recrystallization rate increased as a function of increasing deposition rate, gas purity, and substrate bias. It was hypothesized that high intrinsic stress levels in the deposit provided both vacancies and the driving force for their diffusion to grain boundaries. Grain boundaries composed of {100} planes then adsorbed vacancies and moved by a combination of climb and glide. This movement was made possible by the elimination of barrier impurities, primarily oxygen, with the negative bias applied to the substrate during sputtering.
Channeling-Effect Analysis of Thin Films on Silicon: Aluminum Oxide
Authors: Mitchell I. V. , Kamoshida M. , Mayer J. W.
Published: February 2004

The stoichiometry of films of aluminum oxide deposited hydrolytically onto silicon substrates has been measured by using 2-MeV He-ion backscattering techniques. Oxygen to aluminum ratios of 1.5±0.1 are found for all films grown in the temperature range 600–830°C, despite marked differences in chlorine content and physicochemical properties. The procedures used for extracting line shapes for the two components (aluminum and oxygen) are shown to be generally applicable to many thin film systems. In the particular case of a thin amorphous film overlying a crystalline substrate, channeling effects in the substrate permit a direct determination of the individual line shapes contributing to the total backscattered particle spectrum. Examples are given for stoichiometry tests of amorphous films of aluminum oxide and silicon oxide on silicon-crystal substrates. The composition of thin films of silicon-metal alloys may be measured by the same procedure as illustrated by studies of chromium-silicide formation on silicon substrates. Alternative procedures are discussed for the case of thin films on noncrystalline substrates.
Low-Temperature Electrical Resistivity and Hall Effect of Single-Crystal α-Tungsten Carbide
Authors: Bachmann Kurt , Williams Wendell S.
Published: February 2004

The cubic monocarbides of the transition metals are nonstoichiometric compounds with large residual resistivities due to their high vacancy contents. Hence, the Fermi surface studies needed to test several proposed and conflicting band structures are not feasible. A compound with similar physical properties but different crystal structure, α-WC, can be made with fewer vacancies and offers some hope of providing long enough electron mean free paths for oscillatory studies. We report the first electrical measurements on single crystals of this solid. Indeed, the residual resistivity is far lower than for a cubic carbide, 0.45 μΩ cm, compared with values of 10 or higher. Further improvement appears likely.
Pressure and Temperature Dependence of the Absorption Edge in GaN
Authors: Camphausen D. L. , Connell G. A. N.
Published: February 2004

Measurements of the absorption edge of single-crystal and polycrystal GaN were made as a function of hydrostatic pressure up to 10 kbar at temperatures of 296 and 77 K. Its shift with stress, 4.2±0.4 meV/kbar at 296 K, is similar to the value 5.3±1.0 meV/kbar, calculated for the E0 transition by Camphausen, Connell, and Paul. The absorption near the gap could be separated into a strongly temperature-dependent component for α≳600 cm−1 giving ∂Eg/∂T =−6.7×10−4 eV/K and a less sensitive component for α<600 cm−1. The latter is interpreted as defect- or impurity-induced absorption. The band structure proposed by Van Vechten was adjusted and the results now compare more favorably with our measurements and recent reflectance data.
Polarized Reflectivity Spectra of Tetragonal GeO2
Authors: Kahan A. , Goodrum J. W. , Singh R. S. , Mitra S. S.
Published: February 2004

Polarized infrared reflection spectrum of tetragonal GeO2 has been measured in the region 130–1400 cm−1. Three main resonances, corresponding to the E lim →u type modes of the D4h point group, are observed in the E lim →⊥c spectrum with the TO frequencies at 334, 652, and 709 cm−1 and LO frequencies at 484, 680, and 852 cm−1. The E lim →∥c spectrum consists of one broad band, corresponding to the A2u-type mode, with the TO at 522 cm−1 and the LO frequency at 816 cm−1.
Theory of the Schwarz-Hora Effect
Authors: Kondo Jun
Published: February 2004

A theory of the Schwarz-Hora effect is proposed. Using a simple model of the mechanism of light emission at the target, we first calculate the spectrum of radiation which is emitted when an electron whose wave function is modulated passes the surface of the target. We find that the spectrum has no peak at the frequency of modulation. This is because the electron is recoiled, so that it can take a continuous range of the kinetic energy after the interaction. We then propose that the Schwarz-Hora effect is a phenomenon where many electrons whose velocities are uniform participate coherently. Then, the recoilless process has the amplitude of the order of N, and we find a peak at the modulation frequency. Furthermore, we show that modulation is even unnecessary to obtain the peak. The essential thing is not that we do not know exactly whether the electron has absorbed a photon or not, but that we do not know exactly which one of the electrons has absorbed the photon. We use a simple model of the mechanism of light emission at the target, in which the target is replaced by a transparent dielectric medium. With this model, we find that the above-mentioned features are realized. We calculate the intensity, the direction, and the polarization of the Schwarz-Hora radiation. A question of the relative and absolute intensity of the radiation is discussed.
Nonlinear Optical Susceptibility of a Crystalline Coumarin Dye
Authors: Southgate P. D. , Hall D. S.
Published: February 2004

The nonlinear susceptibilities for second-harmonic generation in 7-diethylamino-4 methyl-coumarin have been measured. They are consistent with values anticipated from the refractive indices.
Sensitivity Enhancement of Superconducting Quantum Interference Devices through the Use of Fractional-Turn Loops
Authors: Zimmerman J. E.
Published: February 2004

A new ``fractional-turn'' configuration for superconducting quantum interference devices provides enhanced sensitivity, with large loop area and low loop inductance. By operating the new configuration at optimum bias frequency (300 MHz or higher), inherent field sensitivities of 10−15 T (10−11 G) or better can reasonably be expected. The operational sensitivity of an instrument using such a device would probably be limited by externally generated noise in most applications. The configuration is readily adaptable to measurements of both diagonal and offdiagonal components of the field gradient.
Design Problems of Superconducting Composites
Authors: Critchlow P. R.
Published: February 2004

Magnetization measurements are reported on a multifilimentary superconducting composite having a copper-cupronickel matrix. The data show that the function of the cupronickel, to reduce transverse currents, is largely nullified by the presence of the copper in a simple composite having cupronickel between filaments with an outer copper sheath.
Thermal Quenching of Tb+3, Tm+3, Pr+3, and Dy+3 4fn Emitting States in La2 O2 S
Authors: Struck C. W. , Fonger W. H.
Published: February 2004

Thermal quenchings of +3 rare-earth line emissions were measured for excitation into the 4fn emitting states. These quenchings differ from corresponding quenchings reported by Wickersheim and Buchanan for band-gap excitation. For Tb+3, Tm+3, and possible Pr+3, the quenchings from the 4fn emitting states are attributed, as in the previously well-established Eu+3 case, to thermally promoted crossovers to Franck-Condon-shifted states.
Normal Freezing with Ideal Binary Solutions
Authors: Li C. H.
Published: February 2004

This communication gives the equations of normal freezing for ideal binary solutions or alloy systems. In these solutions or systems, the liquidus and solidus lines are exponential functions of the reciprocal melt temperature. The equations given relate the fraction p solidified to the melt temperature T, or the solid composition xs to the fraction p solidified.
Chemical Equilibrium in a Stressed Polymer
Authors: Li J. C. M.
Published: February 2004

The effect of stress on chemical equilibrium in solids is treated by a Moutier cycle without using the concept of chemical potential. The derivative of the natural logarithm of the equilibrium constant with respect to stress is a tensorial quantity and after multiplying by RT (R: gas constant, T: absolute temperature) is defined as the strain volume of the reaction.