bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimation of uniaxial stress component in NaCl samples compressed in a tungsten carbide anvil high-pressure x-ray apparatus
Authors: Singh A. K. , Kennedy G. C.
Published: February 2003

The uniaxial stress component (USC) in NaCl samples compressed in a tungsten carbide opposed anvil high-pressure x-ray apparatus has been determined to 10 GPa by a method proposed earlier by Singh and Kennedy. In the pressure range 1–10 GPa, the pressure dependence of the lower estimates of USC can be expressed by the relation t (p) =0.24(±0.04)+0.11(±0.005) p, where t (p) is the USC at a pressure p, t (p) and p being expressed in the units of gigaPascals (GPa). These results have been used to estimate the difference, ΔP, between the pressures calculated from the hydrostatic component of strain and the strain averaged for the first six strong reflections of NaCl. ΔP is found to increase linearly from ∼0.1 GPa at 1 GPa to ∼0.4 GPa at 10 GPa.
Arc-assisted electric-discharge technique for high-pressure cw CO2 lasers
Authors: Crane R. A. , Ghosh A. K. , Tam S. Y. K.
Published: February 2003

A technique utilizing an arc plasma flow for preionizing large volumes of CO2 laser gas mixtures is reported. With this method, stable continuous discharges to 1 atm and power loadings of 400 kW/lb/sec have been obtained using a single arc source. Gain measurements are also made as well as preliminary successful attempts at cw laser action.
Etch pits and dislocations of Ga1−xAlxAs liquid phase epitaxial layers
Authors: Komiya Satoshi , Akita Kenzo , Nishitani Yorimitsu , Isozumi Shouji , Kotani Tsuyoshi
Published: February 2003

The etch pits of Ga1−xAlxAs are revealed by the etchant (H2O/H2O2/CH3COOH/HF) and it is verified that these etch pits correspond faithfully to dislocations using x-ray transmission topographs. The shapes of dislocation etch pits which are revealed by the etchant (1 H2O/1 H2O2/2 CH3COOH/0.5 HF) are either conical on the (100) face of Ga1−xAlxAs with x≳0.1 or pyramidal on the (100) face of Ga1−xAlxAs with x=0.05.
Magnetic anisotropy in single-crystal nickel films electrodeposited on a (110) copper-nickel crystal surface
Authors: Ueda Yuji , Sato Masayoshi
Published: February 2003

Single-crystal nickel films were electrodeposited onto the (110) surface of single-crystal copper-nickel substrates containing from 0 to 12 wt% nickel, and the magnetic anisotropy of the nickel films was measured. Uniaxial anisotropy was observed in addition to the normal magnetocrystalline anisotropy, and the uniaxial anisotropy constant was observed to decrease with the increase of nickel concentration in the substrate; that is, the uniaxial anisotropy of the film is found to be affected by the lattice constants of the substrate.
Magnetic field due to a uniformly wound untwisted flat coil of rectangular cross section
Authors: Whitson J. C. , van Rij W. I.
Published: February 2003

A method for calculating the magnetic field of a rectangular conductor of finite cross section is developed. The coil composed of the rectangular conductor may take any shape in a plane except one where a multivalued function is necessary to describe the path of the current. The method given is exact to the point of a one-dimensional integral. This integral is then evaluated numerically.
Theoretical analysis of AlxGa1−xAs-GaAs graded band-gap solar cell
Authors: Hutchby James A. , Fudurich Richard L.
Published: February 2003

A practical theoretical analysis of an n/p graded band-gap AlxGa1−xAs-GaAs solar cell indicates that the presence of a built-in electric field acting on holes in the surface layer increases the hole collection efficiency of a nearly optimum cell to a maximum of 97.8%. The electric field is created by the band-gap gradient and serves to reduce the surface hole recombination by 97% and reduce the bulk hole recombination by 80%, compared to a similar GaAs cell. These reduced losses increase cell response substantially for wavelengths less than 0.59 μm and yield a maximum air-mass-zero efficiency of 17.7% (not corrected for a 13% front-surface contact). The model includes an optimized antireflection coating, series resistance, and junction-recombination current.
Energetic derivation of the amplification of magnetic waves interacting with a flow of charges in a semiconductor
Authors: Bini M. , Filetti P. L. , Millanta L. , Rubino N.
Published: February 2003

The interaction between magnetic waves in a ferrite and drifting charges in a semiconductor is studied for flat geometries (slabs or plane surfaces), in view of identifying a possible amplification mechanism. This is done through an energetic formulation which gives the imaginary part of the wave propagation constant. Results are derived both for the transverse and the longitudinal magnetization and show that high gain values are theoretically possible. Along the way, the following interesting results have also been obtained: (i) the electromagnetic fields in the absence of interacting charges (’’cold’’ fields) have been obtained for the surface magnetic wave (transverse propagation) together with the dispersion curve; (ii) the correct expressions of the rf fields have been calculated for the slab, both for the transverse and the longitudinal propagation.
Current injection in insulators containing traps under spherical and cylindrical flow
Authors: Dahiya R. P. , Mathur V. K.
Published: February 2003

In view of the importance of various contact configurations for devices, the current injection for spherical and cylindrical flow in an insulator containing traps is discussed. The traps are considered to be distributed in energy according to distribution proposed earlier by the authors. The method of regional approximation has been applied to obtain complete I-V characteristics from the Ohmic to the pure space-charge region.
Experimental study of flexural vibrations in thick beams
Authors: Heybey O. , Karasz F. E.
Published: February 2003

The resonant frequency spectrum for flexural vibrations in thick rectangular beams has been analyzed in terms of the elastic parameters of the beam material. An apparatus for the precise measurement of such resonant frequencies up to the tenth or higher modes in the range ∼0.3 to ∼20 kHz is described together with results for sample aluminum beams. By comparing the measured frequency spectrum with that calculated from a first-order theoretical treatment it has been found possible to derive both the elongational modulus and Poisson’s ratio from such a measurement, thereby completely characterizing the elastic response of an isotropic material.
Mischmetal-cobalt as a permanent magnetic material
Authors: Nagel H. , Klein H. P. , Menth A.
Published: February 2003

Permanent magnets based on MMCo5(MM=mischmetal) were produced by powder metallurgical means with a coercivity IHc=9 kOe, a remanence Br=7.8 kG, and an energy product of (BH)max=14.5 MG Oe. These values could be increased by substituting some MM by Sm and Nd. The influence of MM composition on both the primary magnetic properties, as measured on single crystals, and the secondary magnetic properties and their temperature dependences was studied. The saturation magnetization Ms, the remanence Br, and the anisotropy field Ha vary almost linearly with composition. In contrast, IHc showed a more complex compositional dependence; it increases with increasing La content, decreases with Ce and Pr content, and passes through a maximum with increasing Nd content. The temperature dependence of IHc reflects the temperature dependence of Ha from the different compositions. A two-step postsintering heat treatment was developed which results in good hard magnetic properties. The first step of 1 h at 1250 K is a homogenizing treatment, the second step of 1 h at about 620 K seems to cause small 2-17 precipitates to form which act as pinning centers.
Bubble dynamics in multilayer garnet films
Authors: Henry R. D. , Elliott M. T. , Whitcomb E. C.
Published: February 2003

The results of transient motion of bubbles in multilayer films are presented. These results are compared to present models of dynamic conversion and ballistic overshoot, followed by a discussion of the possible spin dynamics in multilayer films.
Image formation by nuclear magnetic resonance: The sensitive-point method
Authors: Hinshaw Waldo S.
Published: February 2003

An image formation method, using nuclear magnetic resonance techniques, has been developed which provides direct and detailed information on the interior details of heterogeneous samples. Time-dependent magnetic field gradients are used to limit and control the region of spatial sensitivity of a standard pulsed NMR spectrometer. A continuous string of intense phase-alternated rf pulses is used to provide a continuous monitor of the nuclear magnetization. The image is produced by directly plotting the phase-detected resonance signal on a xy plotter as the limited region of spectrometer sensitivity is scanned through the sample. An analysis of the method in terms of the phenomenological Bloch equations, a description of the experimental method, and a representative selection of images are presented. A spatial resolution of about 0.3 mm has been achieved.
Sensitivity of x-ray films. I. A model for sensitivity in the 1–100-keV region
Authors: Brown D. B. , Criss J. W. , Birks L. S.
Published: February 2003

A model for the sensitivity of x-ray film in the 1–100-keV region is presented. It provides the only known method for the interpretation of densities due to polychromatic exposures in the low-energy (1–5 keV) region. A computer program utilizing the model has been found to be a convenient and flexible tool for predicting and interpreting low- and high-energy film densities. The predicted densities were found to agree with experimental data for Kodak No-Screen film with an error of less than 20%. The model is a schematic representation of the physical processes which take place during x-ray transport through the emulsion, the production of developable grains, development, and densitometry. It contains an allowance for the different fractions of scattered light collected by different densitometers. In the low-energy region it handles x-ray absorption using a theory for absorption in heterogeneous media. In the high-energy region an enhanced sensitivity due to the effect of photoelectrons is included.
Superconductor coil geometry and ac losses
Authors: Pierce T. V. , Zapata R. N.
Published: February 2003

An empirical relation is presented which allows simple computation of volume-averaged winding fields from central fields for coils of small rectangular cross sections. This relation suggests that, in certain applications, ac-loss minimization can be accomplished by use of low winding densities, provided that hysteresis losses are independent of winding density. ac-loss measurements on coils wound of twisted multifilamentary composite superconductors show no significant dependence of ac losses on winding density, thus permitting the use of winding density as an independent design parameter in loss minimization.
Electroluminescence observation and x-ray topographic study of a nitrogen-doped GaP-LED
Authors: Funakoshi Kiyohiko , Kishino Seigô
Published: February 2003

The lattice defects in nitrogen-doped GaP light-emitting diodes (LED’s) are investigated by taking an electroluminescence (EL) pattern and an x-ray topograph of a small LED chip. The one-to-one correspondence between the dark lines in the EL pattern and the screw dislocations is obtained.
Field emission from LiIn single crystals
Authors: Kuriyama Kazuo , Iwamura Kokuya , Masaki Tomomi , Okada Akira
Published: February 2003

Field emission from single crystals of LiIn, which behave as either narrow-gap semiconductors or semimetals, have been studied using a field emission microscope. A linear Fowler-Nordheim relationship was found. The specimen surfaces were believed to be contaminated.
Application of the simplified particle model theory to the diffuse reflectance properties of powdered layers
Authors: Simmons E. L.
Published: February 2003

The simplified particle model theory of diffuse reflectance spectroscopy is used to relate the reflectance and transmittance of a powdered layer to the fundamental optical parameters. The resulting equations are compared with those obtained by the use of the Kubelka-Munk theory.
Transient and steady-state domain-wall velocities in a garnet film
Authors: Konishi S. , Mizuno K. , Narita K.
Published: February 2003

The transient and steady-state domain-wall velocities are measured by a refined collapse method in a bubble garnet film. The usual average velocity as a function of pulse width shows very large velocity for short pulse width and relaxation to the steady state. The instantaneous velocity defined simply from the increments of wall displacement distance and pulse width shows that the velocity is nearly steady over about 10 ns. The steady-state velocity below the drive field of 500 Oe includes both a velocity component independent of drive field and a component increasing linearly with field. The former mode is not operative above 900 Oe. These are discussed from the theoretical predictions, together with the wall velocity in hard bubbles.
Dissociation efficiency of electron-beam-triggered discharges for initiating atmospheric-pressure H2-F2 lasers
Authors: Whittier J. S. , Lundquist M. L. , Ching A. , Thornton G. E. , Hofland R.
Published: February 2003

Time-resolved uv absorption measurements of the rate of F2 disappearance have been compared with a theoretical pulsed chemical laser code to infer electrical dissociation efficiencies of electron-beam-irradiated discharges. The results indicate that a 400-keV, 50-nsec e-beam of A/cm2 dissociates approximately 0.3% of the reactants initially present in dilute F2/H2 mixtures, producing four chain carriers per ionizing collision. With the addition of a discharge field at 80% of the self-breakdown limit, initial reactant dissociation increases to approximately 1.1%, corresponding to 15 chain carriers per ionizing event and a dissociation efficiency of 7.5%. An earlier analytical plasma model of reactant dissociation that has been generalized to account for the presence of Ar and H2 suggests that heating of the negative ions of fluorine, leading to electron detachment in heavy-particle collisions and direct electron-impact dissociation of reagents by slow electrons become dominant mechanisms with the application of a strong undervolted field. In general, the approximate plasma analysis is shown to yield results that are in qualitative agreement with the experimental data.
Detection of weakly absorbing gases using a resonant optoacoustic method
Authors: Kamm Roger D.
Published: February 2003

Recently developed optoacoustic techniques have greatly expanded our capability of measuring ultralow concentrations of infrared absorbing gases. Devices of this type include both the spectrophone which was introduced by Kreuzer in 1971 and the resonant spectrophone first considered by Dewey, Kamm, and Hackett in 1973. The advantage in the resonant method lies in the capability of accumulating energy in a standing acoustic wave, thereby providing for an effective means of signal amplification. In this paper we present the theory for the resonant acoustic response to an excitation of known characteristics with particular emphasis placed on the dissipative processes which act to limit the extent of resonant enhancement. We also investigate both theoretically and experimentally the effect of a multiple-pass configuration in which the laser beam undergoes numerous reflections, thereby increasing the total energy imparted to the gas. This description leads to a means of objectively comparing a resonant optoacoustic system to other detection devices. This same approach introduces an expression which can be used to optimize the resonant technique with respect to the variable parameters.
Concentration dependence of the gain spectrum in energy-transfer dye mixtures
Authors: Urisu Tsuneo , Kajiyama Kenji
Published: February 2003

Acceptor concentration dependence of the gain-spectrum peak was measured in coumarin 30 (donor) and rhodamine 6G (acceptor) mixtures. Change of the gain spectrum due to the energy-transfer reaction is attributed to the change of the effective fluorescence lifetime. From the concentration dependence of the effective fluorescence lifetime, rate constants were obtained as follows: kda (for resonance energy transfer) =4×10−11 cm3/sec and k′da (for radiative energy transfer) =2×10−9 cm3/sec. Consequently, the radiative energy transfer was the most dominant mechanism in the energy-transfer reaction.
Amplification of Gaussian beams through a gaseous medium
Authors: Maeda Hisatoshi
Published: February 2003

An amplification of the Gaussian beams in an active gaseous medium, possesing a quadratic radial variation of the population inversion, is considered. The gain curve is shown to have an asymmetrical shape. For a given population inversion, the maximum gain is calculated to be attainable at higher frequency than that of the atomic resonance, both in unsaturated and saturated operations.
Acoustic harmonic generation in piezoelectric semiconductors with energy-dependent relaxation times
Authors: Singh S. P. , Sharma S. K.
Published: February 2003

In this paper, we study the second harmonic generation in piezoelectric semiconductors with energy-dependent relaxation times in the presence of an acoustic wave. The interaction of electrons with the acoustic wave is taken into account through piezoelectric coupling. In contrast to earlier works, we use the collision term, given by Sharma and Kaw which is valid for energy-dependent relaxation times and use it to solve the Boltzmann equation. Our calculations show that the values of the second harmonic yield for various values of ql differ significantly for ql≪1 and are close for ql≫1 with the corresponding values obtained by using the Cohen-Harrison-Harrison (CHH) collision model. Further, the second harmonic yield has a maximum at ql≫1.
Adhesion coefficients of plated contact materials
Authors: Sharma S. P.
Published: February 2003

Adhesion (sticking) of sealed contacts may cause serious problems in certain applications. Adhesion occurs when two surfaces are pressed together under a purely normal load or under combined normal and shear forces. An experimental apparatus has been designed and constructed so that the coefficient of adhesion can be measured accurately in a controllable and reproducible manner. This paper reports measurements of adhesion coefficients σ of different plated materials in sealed contact applications. The values of σ are reproducible within 3%. It has been found that ruthenium- and rhodium-plated contacts and soft diffused gold contacts yield the minimum coefficient of adhesion.
Characterization of diodes in saturated-velocity regime under arbitrary injection
Authors: Hariu T. , Shibata Y.
Published: February 2003

Static and transient current characteristics in the saturated-velocity regime under arbitrary dependence of injection on the field were analyzed. The expressions for the transient behavior were derived analytically and were found to be determined uniquely by the ratio of the transit time to the injection-controlling time constant τc=ε/σc where σc is the contact conductance. These are useful for the characterization of devices operating in this regime, especially for the derivation of the contact characteristic.
In1−xGaxP1−zAsz double-heterojunction-laser operation (77 °K, yellow) in an external grating cavity
Authors: Wright P. D. , Coleman J. J. , Holonyak N. , Ludowise M. J. , Stillman G. E. , Rossi J. A.
Published: February 2003

In1−xGaxP1−zAsz double-heterojunction lasers fabricated by liquid-phase epitaxy are operated at λ ≲6000 Å (77 °K) in an external grating cavity to provide wavelength-selective optical feedback. Diodes with and without antireflecting coatings and with heterobarrier heights of ∼20, ∼65, and ∼90 meV are examined. With external grating feedback, laser operation occurs at reduced threshold current densities and narrower linewidths and, depending upon heterobarrier height, can be tuned over an appreciable wavelength range. Within certain tuning limits on either side of line center, the carrier recombination is drawn to the grating wavelength and, as in earlier work, laser operation on a homogeneously broadened line is observed. Beyond these limits, particularly for excitation just above the threshold of stimulated emission, laser operation on an inhomogeneously broadened line can be distinguished. These observations showing that homogeneous and inhomogeneous line broadening occur in a semiconductor laser are accounted for by a simple model of the recombination kinetics.
Backscattering measurements on Ag photodoping effect in As2S3 glass
Authors: Yamamoto Yasuhiro , Itoh Tadatsugu , Hirose Yooichi , Hirose Haruo
Published: February 2003

350-keV He+ backscattering analysis was applied to the investigation of Ag photoinduced diffusion into As2S3 glass and proved to be suitable for the present purposes. Silver atoms diffuse into As2S3 by photoirradiation (termed ’’photodoping’’). Photodoped Ag concentration is nearly uniform and falls abruptly beyond a certain depth. The concentration of S in the photodoped region is nearly equivalent to that in As2S3. Preirradiation of As2S3 before Ag deposition enhances Ag diffusion, which results in a tailing of the Ag concentration. The preirradiation effect disappears after a long period. Thermal diffusion of materials was also investigated for comparison.
Magnetic and magneto-optic properties of ferromagnetic MnCuBi thin films
Authors: Katsui A.
Published: February 2003

Magnetic and magneto-optic properties of thin films composed of the Mn-Cu-Bi ternary system are reported. The typical composition is MnCuBi having a moderate Curie temperature around 180 °C. The films can be prepared either on a quartz or glass substrate by vacuum deposition. The easy axis of magnetization of the films is normal to the film plane. The hysteresis loop is rectangular, that is, the remanent magnetization equals the saturation magnetization. The Faraday rotation F is about 4×105 deg/cm for the wavelength 5145 Å and 2.5×105 deg/cm for 6328 Å. The magneto-optic figure of merit 2F/α, where α is the optical absorption coefficient, is 1.8° for a wavelength of 5145 Å and 1.3° for 6328 Å. These figures of merit are equal to one-third to one-half of those of MnBi and are not smaller than those of the other magneto-optic materials. The films are very resistant to oxidation by the surrounding atmosphere. The MnCuBi seems promising as a magneto-optic memory medium.
Photoluminescence of ZnTe
Authors: Woody W. R. , Meese J. M.
Published: February 2003

The photoluminescence of ZnTe has been monitored at 4.2 °K as a function of isochronal annealing in an argon atmosphere. Prior to annealing, all as-grown samples exhibited a strong bound-exciton line at 5220 Å (I1) and two distinct edge-emission series, the first at 5318 Å (A1 series) and the second at 5543 Å (B series). The A1-series zero phonon line has been attributed by others to a free-to-bound transition to the first ionization level of the double-acceptor zinc vacancy and the zero phonon line of the B series to the second ionization level of this defect. After a 10-min anneal at 300 °C in flowing argon, a marked increase in the intensity of the I1 exciton and the B-series transitions was observed. In addition, a new A-series line (A0) at 5300 Å was produced by this heat treatment in all samples studied. The temperature dependence of this new A0 line as compared to that of the A1 transition, and the possible observation of an associated bound exciton at 5218 Å, suggest that a distinct shallow acceptor level of unknown origin has been detected at 0.052 eV in addition to the acceptor level at 0.060 eV associated with the A1 transition. These two ionization energies correspond well to those found by electrical measurements, which have been attributed by others to the first ionization level of the zinc vacancy and a group-I substitutional acceptor.
Transverse magnetoresistance and its temperature dependence for high-purity polycrystalline aluminum
Authors: Krevet B. , Schauer W.
Published: February 2003

Polycrystalline-aluminum-tape samples of 0.3×6 mm2 cross section have been used to measure the zero-field resistivity and the transverse magnetoresistance up to 3.9 T. The main purpose of our investigation was to study the temperature and purity dependence of the magnetoresistance. Measurements were taken continuously in the temperature range 4.2–32 K for six samples differing in purity. The bulk residual resistivity ratio rb chosen as a measure of purity varied from 2400 to 30 000. In the high-field region the magnetoresistance increases with temperature up to a maximum at about 20 K. The maximum itself increases with purity and leads for the purest sample to a resistivity increase by a factor of 6.8 (B=3.9 T, T=17 K). The unusual temperature behavior of the resistivity with and without magnetic field, which means a violation of the Kohler and Matthiessen rule, is discussed and explained regarding the anisotropic electron-phonon scattering. Following the theoretical concept of Kagan a qualitative agreement could be obtained. Measurements of the Hall effect on a rb=24 500 sample were performed to support the interpretation of the magnetoresistance results.
Debye-series approach in analysis of transient radiation from a Hertzian dipole antenna in a cavity in a medium
Authors: Pogorzelski R. J. , Nevels R. D. , Wilton D. R. , Lewis G. C.
Published: February 2003

We present an analysis of the radiation produced when an electrically short transiently excited dipole antenna radiates from within a cavity in a medium. We show that, if one formulates the problem in terms of a Debye series in the Laplace domain, complete results may be obtained analytically in the lossless case. When loss is present in the surrounding medium, some numerical evaluations are required to obtain the complete solution. As an example we treat the problem of communication between a transmitting antenna located beneath a metal craft on the surface of a lake and a receiver some distance below the surface.
Sources of photoemission in Na3Sb thin films
Authors: Fisher D. G.
Published: February 2003

Na3Sb thin films were formed by first depositing an Sb layer and then depositing Na from a molecular-beam source; the Na-Sb reaction took place at room temperature. The average film composition during Na deposition was determined with a quartz crystal microbalance. Photoemissive spectral yield and photoelectron energy distribution data were obtained as a function of film composition. Values for band-bending parameters, photosensitive layer thickness, and photothreshold energy were determined from an analysis of the spectral yield data. In the Na to Sb ratio range of approximately 2 : 1 to 3 : 1, the photosensitive layer thickness increases from less than 20 Å to greater than 300 Å, suggesting that the Na3Sb growth proceeds from the surface at the completion of Na2Sb growth. The threshold region of the spectral yield curves fits a model for indirect transitions from surface states at the Fermi energy. The energy distribution data confirm that the transitions are indirect. A separate peak in the energy distribution data is attributed to emission from bulk donor states.
Oxidation of amorphous Pd78Au4Si18 alloy studied with Auger electron spectroscopy
Authors: Lo C. C. , Tompkins H. G.
Published: February 2003

The oxidation of the amorphous Pd78Au4Si18 alloy aged at temperatures of 150 to 300 °C for 1 to 20 days is investigated using Auger electron spectroscopy and ion-beam etching. Samples are characterized by x-ray diffraction and electrical contact resistance at each aging stage. Partially crystallized samples as well as pure palladium samples also are evaluated for comparison. Oxidation is controlled by the inward diffusion rate of oxygen for both the alloy and elemental Pd samples. The oxygen front for the alloy is deeper than that for Pd. Oxygen depth profiles for Pd samples decline monotonically and gradually, but for the alloy they have up to three plateaus. The composition in each plateau zone is analyzed by studying the Si-LVV Auger spectrum. Partial crystallization prior to the oxidation has little effect on the oxidation rate of the alloy. Even with an apparent oxide layer 90 Å thick, the alloy shows little increase in resistance. This could be explained by nonuniformities in the layer.
GaAs double heterostructure lasers fabricated by wet chemical etching
Authors: Merz J. L. , Logan R. A.
Published: February 2003

GaAs double heterostructure lasers compatible with monolithic intergration of optical devices have been fabricated by wet chemical etching. Results for a variety of laser orientations are reported. External differential quantum efficiencies as high as 18% have been achieved, as well as threshold current densities as low as 4.2 kA/cm2. An analysis for the evaluation of etched-mirror properties is presented. Using this analysis, it was found that etched mirrors had reflectivity R?0.22±0.05 and scattering losses S=0.3±0.1.
Infrared second-harmonic generation in nonbirefringent cadmium telluride
Authors: Piltch M. S. , Cantrell C. D. , Sze R. C.
Published: February 2003

We have experimentally demonstrated infrared second-harmonic generation in the nonbirefringent zinc-blende crystal cadmium telluride using properly oriented plates in which the optical path length is equal to an odd number of coherence lengths. The present process has the promise of scalability to high power, since suitable zinc-blende cubic crystals can be grown in large boules of excellent optical quality.
Interaction of intense laser beams with plasma waves: Stimulated Raman scattering
Authors: Sodha M. S. , Sharma R. P. , Kaushik S. C.
Published: February 2003

This paper presents an investigation of the coupling of high-power Gaussian laser beams with electron plasma waves in a collisionless plasma. The Gaussian intensity distribution of the laser beam causes the redistribution of the carriers in the transverse plane due to a ponderomotive force and is shown to lead to the enhancement in the amplitude of the plasma wave. Stimulated Raman scattering of the laser beam corresponding to the modified plasma wave has also been evaluated.
One-dimensional acceleration waves and acoustoelectric domains in piezoelectric semiconductors
Authors: McCarthy M. F. , Tiersten H. F.
Published: February 2003

The theory of acceleration waves is applied in the analysis of the formation and propagation of acoustoelectric domains in piezoelectric semiconductors. A one-dimensional version of the general nonlinear electroelastic equations for deformable semiconductors recently presented is employed in the analysis. Consequently, the mechanical and dielectric nonlinearities are included in the analysis as well as the semiconduction nonlinearity. Equations are derived for both the propagation velocity and the amplitude of the growing disturbance as a function of the state of the material immediately ahead of the wave front. These rather general results are specialized to the case of a homogeneous steady state ahead of the wave and the condition for the threshold field is determined. In this latter case the wave front propagates with constant velocity and the amplitude equation indicates the formation of a shock in a finite time for conditions conductive to domain formation. When the electrical conduction equation, which can be quite general in this treatment, is specialized to the form usually employed for semiconductors, the aforementioned more general condition for the threshold field reduces to the known result.
Electron-deposition-induced spallation in tantalum
Authors: Boade R. R. , Burchett O. L.
Published: February 2003

Spallation induced in thin specimens of tantalum by rapid in-depth energy deposition has been studied in a series of electron-beam experiments in which peak deposition levels were varied from ∼130 to ∼700 J/g. Incipient spall was observed at ∼225 J/g. Analysis of the experiments with a one-dimensional wave-propagation code indicated that the tensile stress at the incipient spall level was ∼26 kbar, which is considerably lower than the ∼70−kbar tensile stress previously found to produce comparable damage in room-temperature plate-impact experiments. The analysis further indicated that strains induced in the samples at the incipient spall level were about the same (0.035) for both types of experiments after accounting for the thermal-expansion component of strain in the electron-beam experiments. This observation supports a contention that induced mechanical strain would be a suitable criterion for use in describing the spallation phenomenon in uniaxial-strain situations.
On the theory and analyses of the ac characteristics of defect thin films
Authors: Nadkarni G. S. , Simmons J. G.
Published: February 2003

The analyses of Nadkarni and Simmons were not claimed to be completed and definitive.
Spacing dependence of the minimum drive field for 16-μm-period field-access bubble-domain devices
Authors: George P. K.
Published: February 2003

The spacing dependence of the minimum drive field for 16-μm-period field-access devices has been experimentally measured and shown to be consistent with existing model calculations.
Microwave amplification in GaAs subject to crossed static electric and magnetic fields
Authors: Hsieh H. C.
Published: February 2003

The condition for the amplification of an electromagnetic wave, with a microwave frequency, propagating in the direction perpendicular to crossed static electric E0 and magnetic B0 fields in n-type GaAs at room temperature is derived from the dispersion relationship. It is shown that a wave with a phase velocity less than the electron drift velocity in the direction of wave propagation may be amplified, provided that the value of B0, E0, and the wave frequency f are proper.
Initiation of cross-slip near the head of a screw dislocation pile-up
Authors: Adelman N. T. , Dundurs J.
Published: February 2003

Initiation of the Koehler-Orowan double cross-slip mechanism is investigated, where the barrier to cross-slip is provided by a Peierls-Nabarro force. Criteria are established for the survival and growth of a thermally produced double jog near the head of a screw dislocation pile-up which are shown to be applicable under normal temperature and stress conditions.
Study of evaporated metal nuclei by Auger spectroscopy
Authors: Baetzold R. C.
Published: February 2003

Auger studies of silver, copper, gold, and nickel nuclei evaporated onto carbon films show that a large fraction of the metal diffuses into the film. Subsequent exposure of the metal nuclei on the surface to room atmosphere for one week results in severe contamination by S. Relative changes in the Auger peak positions for Au evaporated on carbon have been recorded as a function of coverage. The studies indicate that the changes are complete at 2.5×1015 atoms/cm2. Carbide formation has been observed in the case of evaporated Fe and Al on carbon, but not for any of the other metals considered here.
Emission-angle dependence of energy spectra of 24.8-MeV electrons passing through thick materials
Authors: Mikado T. , Tomimasu T. , Yamazaki T.
Published: February 2003

Transmitted energy spectra of 24.8-MeV electrons were measured for C, Al, Cu, and Pb absorbers of thicknesses ranging from 1 to 3.6 g/cm2 at emission angles of 0°, 5°, 15°, 30°, and 60°. The minimum point (valley) of the spectrum was found to lie below 5 MeV for most cases studied. Relative intensity of the peak to that of the valley is compared with Molière’s scattering theory and found to be not only a parameter to express the spectrum shape, but also a good measure of angular distributions of multiply-scattered electrons at emission angles up to 15°.
Shock augmentation by bubble flow
Authors: Leiber C. O.
Published: February 2003

An approach to the Chapman-Jouguet free detonation model of liquid explosives is given. It is based on the assumption that bubbles from the high-pressure side of the shocked medium overtake shock velocity and expand into the low-pressure side. In this way, the expanding bubbles become strong sources with a near and far field, which may be augmentated by the shock zone considered to be a resonator. Detonation in this way is a source/resonator system and the same behavior is also observable on inerts. In this model the low-velocity detonation is necessarily contained. The problem of the Hugoniots of porous media is also affected, and due to the results of this model and experimental facts, one may suppose that a cavitation of liquids occurs by a compressive shock.
Stress threshold for precursor decay in LiF
Authors: Dick J. J. , Duvall George E. , Vorthman J. E.
Published: February 2003

Single crystals of LiF have been mechanically shocked by projectile impact so as to produce shocks propagating in a 〈100〉 direction. Velocities of projectiles have been varied to produce shock pressures from 4.9 to 28.6 kbar in the LiF. Pressures were measured with thick quartz gauges after shock travel distances of approximately 3 mm. The 4.9-kbar wave was perfectly elastic. The precursor of an 8.3-kbar wave showed no attenuation, but stress relaxation occurred between precursor and plastic shock. A 10.4-kbar precursor was measurably attenuated from its impact value. These results are taken to indicate a threshold shear stress between 2.4 and 3.0 kbar for nucleation of dislocations in the shock front.
Broadening and absorption coefficients in N14H2D
Authors: Plant T. K. , Abrams R. L.
Published: February 2003

The magnitudes of the pressure broadening and linear absorption coefficients have been measured for the Stark tunable (0a,404,4) → (1a,505,5) transition in N14H2D using a CO2 laser operating on the P (20) 10.59-μm line. Two separate analysis methods give consistent results which are substantially different from values previously reported.
Infrared absorptances of partially ordered alloys at elevated temperatures
Authors: Wieting T. J. , Schriempf J. T.
Published: February 2003

The infrared absorptances of highly polished Ti-6Al-4V and 304 stainless steel have been measured between 2 and 20 μm and at temperatures up to 550 °C. Small positive temperature coefficients for both alloys were observed. A generalized Drude model has been developed to interpret the data; the weak temperature dependence of the absorptance has been attributed to the relatively small effect of phonon scattering in these disordered alloys.
Detection of sodium trace contamination in furnace atmospheres at 1000 °C
Authors: Mayo Santos , Keller Richard A. , Travis John C. , Green Robert B.
Published: February 2003

Free sodium atoms were detected by resonance fluorescence in an open contaminated quartz tube heated to 1000 °C. The quartz tube and furnace were similar to those used in semiconductor device processing. Fluorescence was excited by a cw dye laser tuned to the sodium D1 or D2 transition and directed along the axis of the furnace. Fluorescence from the sodium D2 line emitted in the axial direction was collected by a telescopic system and focused onto a photomultiplier tube. The estimated minimum detectable sodium density in the furnace is 5×105 atoms/cm3. No free sodium was detectable in a processing tube that had not been intentionally contaminated.
The continuous coating of glass fibers
Authors: Torza S.
Published: February 2003

We analyze a new process for in-line coating of thin glass fibers as they are produced by horizontal and vertical fiber-drawing machines. The process makes use of a new coating applicator designed to prevent contact between the freshly drawn fiber and wicks, dies, or other surfaces which may cause abrasion of the fibers and hence losses in their tensile strength.
Modal characteristics of optical stripline waveguides
Authors: Butler J. K. , Wang C. S. , Campbell J. C.
Published: February 2003

A theoretical model of the optical stripline waveguide is presented. The structure consists of an underlying substrate with an index n3, a slab of thickness d having a refractive index n2, and an overlayed stripe of width 2w and index n1; the index n2≳n1, n3. Optical confinement of the fields to the slab is obtained in the vertical direction by dielectric discontinuities while confinement in the lateral direction occurs because of spatial interference of a continuum of plane waves. Modal cutoff conditions are determined as a function of the slab thickness d and the stripe width 2w for a range of index steps. The field profiles in the lateral directions are compared with experimental profiles. These profiles show that the fields decay exponentially in the slab away from the stripe. The coupling between two parallel stripes is discussed and coupling lengths are calculated. The agreement between theory and experiment is, in most cases, better than 10%.
Kerr coefficients of polychlorinated biphenyls and chlorinated naphthalene
Authors: Misakian Martin , Hebner Robert E.
Published: February 2003

The electro-optic Kerr coefficients of two polychlorinated biphenyls and chlorinated naphthalene have been measured to an accuracy of ±7% using a comparative technique. Physical properties of the fluids relevant to application in electro-optic devices are discussed.
Design considerations for nonreciprocal integrated optical devices
Authors: Yamamoto Sadahiko , Makimoto Toshio
Published: February 2003

This paper is concerned with the design of nonreciprocal thin-film optical devices containing gyrotropic and anisotropic materials using one-section configurations rather than the composite cascade configurations of previous designs. The analysis is based on the transmission-matrix description of TE-TM mode coupling. Circuit configurations are presented for two typical devices; the unidirectional mode converter and the TE-TM gyrator. A discussion is also given to the deterioration of the device performance due to the film-thickness deviation from the prescribed value for the example of the unidirectional mode converter utilizing the LiIO3/YIG/GGG layered structure.
New figure of merit for transparent conductors
Authors: Haacke G.
Published: February 2003

A figure of merit for transparent electrode materials has been defined by φTC=T10/Rs, where T is the optical transmission and Rs is the electrical sheet resistance. Expressions are derived to predict the transparent electrode properties of a material from its fundamental electrical and optical constants. The performance of thin metal films is compared to semiconducting oxide coatings.
Combined RHEED–molecular-beam study of the adsorption of Cd on Ge(111)
Authors: Matysik K. J.
Published: February 2003

The adsorption of Cd on Ge(111) was studied with combined RHEED-MB techniques. The reciprocal lattice of the interface was mapped as a function of absolute adatom density. For low coverages, of the order of 10−3 monolayers, the Cd adatoms clustered to form islands which were either static with random orientation with respect to the substrate or mobile ’’spinners’’. At a density of σ=3.2×1014/cm2 the islands took on substrate symmetry and formed an incommensurate overlayer having the structure of the basal plane of hcp Cd. The observations are discussed in terms of dangling-bond densities and the uncertainties in the absolute density determination described.
Field-induced deformation of hybrid-aligned nematic liquid crystals: New multicolor liquid crystal display
Authors: Matsumoto Shoichi , Kawamoto Masahiro , Mizunoya Kiyoshi
Published: February 2003

Electric field-induced deformation is studied in a unique hybrid-aligned nematic (HAN) cell, in which the director of a nematic liquid crystal (LC) with either positive or negative dielectric anisotropy is varied continuously, lying perpendicular to one substrate and parallel to the other. The experimental results show the absence of threshold field in the birefringence–vs–applied voltage relationship as well as the slow variation of birefringence with voltage; these phenomena are analyzed in terms of the Frank-Oseen continuum theory. Also, the above characteristics of HAN are demonstrated to have such advantages in multicolor LC display applications as low operating voltage and fairly good color separation together with uniform and bright color generation.
Fatigue-induced photoelectron enhancement (exo-electron) from aluminum
Authors: Thompson D. O. , Young Robin , Alers G. A. , Smith Tennyson
Published: February 2003

Photoelectron emission measurements, alternating on the same surface with ellipsometric and surface-potential-difference measurements, have been made during cyclic flexure fatigue of aluminum samples. A high cyclic fatigue rate was achieved with a unique electromagnetic drive. Measurements were conducted as a function of strain amplitude and oxide-film thickness. Argon-ion bombardment was used to achieve a pure aluminum surface. Most of the measurements, including Auger spectroscopy, were conducted in ultrahigh vacuum. The fatigue-enhanced optically stimulated electron emission (OSEE or exo-electron current) increases with strain amplitude or surface roughening and decreases with oxide thickness. The mechanism of emission is discussed in relation to enhanced plasmon coupling due to surface roughening during fatigue cycling.
Dynamic behavior of high-current arcs in a capillary
Authors: Ueda Yoshihiro , Miyamoto Toshio , Nitta Tohei , Ito Toshio
Published: February 2003

The optical and electrical characteristics of high-current discharge in a capillary in helium were studied in the range of initial pressure from 10 to 760 Torr. The discharge current increased to a peak of 8 kA in 1.5 μsec after breakdown. The duration of the current was about 15 μsec. Two different types of peak were observed during the temporal changes of arc voltage. No such peaks of arc voltage have ever been observed in free-burning arcs. To study the cause of these voltage peaks, temporal changes in the emission spectra, electron density, and temperature of the arc were measured and analyzed. One type of voltage peak appears at high initial pressures above 100 Torr and is related to the kink instability which occurs at very high pressures in the capillary. The pressure of the arc is estimated to be 90 atm when the initial pressure is 1 atm. The other type of voltage peak observed at low initial pressures below 100 Torr is attributed to wall evaporation which causes a reduction in the electron temperature in the arc. It has also been proven that local thermodynamic equilibrium (LTE) between the temperatures of heavy particles and electrons and also between the particle densities of singly and doubly ionized helium are not always established in arcs confined in capillaries.
Microwave measurement of plasma density fluctuation amplitudes
Authors: Powers E. J. , Simonen T. C.
Published: February 2003

A microwave beam is used to detect ion-cyclotron oscillations in the 2XIIB mirror device. A model is used to estimate electron density and electric field oscillation amplitudes from measured modulation sideband intensities. Semiquantitative agreement is obtained with electrostatic probe measurements.
Optical properties of sulfur-doped silicon
Authors: Engström O. , Grimmeiss H. G.
Published: February 2003

Photocurrent measurements in sulfur-doped silicon p-n junctions have been used to determine optical threshold energies and spectral distributions of the photoionization cross sections associated with two deep sulfur centers in silicon. In addition, absolute values of three of the cross sections have been determined. It is shown that the optical cross-section spectra for the excitation of electrons from the sulfur centers to the conduction band cannot be described by the Lucovsky model. On the other hand, they are not in contradiction with the Pantelides-Sah correction of KL-EMT. The temperature dependence of the energy position of the sulfur centers is discussed.