bluuebunny/crossref_metadata_2025 huggingface dataset:
High-energy electron-beam deposition onto a hot graphite surface
Authors: Robin James E. , Srivastava R.D.
Published: January 2004

The momentum transfer and blow-off vapor yield resulting from the deposition of a pulsed high-power electron beam onto a plane graphite target with surface temperatures of 300°K and 5000°K are examined experimentally. The results show that with identical electron beams the momentum transfer and vapor yield are between two and three times larger when irradiating the 5000°K surface as compared with the 300°K surface.
Effect of Doppler ambiguity on the measurement of turbulence spectra by laser Doppler velocimeter
Authors: Wang C.P.
Published: January 2004

For the measurement of turbulent flows, the effect of finite transit times of scatterers to cross the scattering region in a laser Doppler velocimeter is discussed. The result shows that in the measurement of the velocity spectrum, it is equivalent to a white spectrum noise with an amplitude inversely proportional to the average transit time. Theoretically, the noise becomes negligibly small when the wavelength of the laser light becomes very short.
Intrinsic coercive force in (Pr,Sm)Co5 as a function of samarium content
Authors: Carriker R.C.
Published: January 2004

A strong dependence of the intrinsic coercive force on the amount of samarium present in (Pr,Sm)Co5 permanent magnets has been observed. These magnets were nominally 63 wt% Co, with five compositional variations in the rare-earth content ranging from 20.70 wt% Pr−16.30 wt% Sm to 27.75 wt% Pr−9.25 wt% Sm being studied. The sintering temperatures were varied for each composition, holding the sintering time constant at 30 min. The maximum intrinsic coercive force achieved during sintering increased rapidly with samarium content from 2.6 kOe for the 9.75 wt% Sm alloy to 22.4 kOe for the 16.3 wt% Sm alloy.
Transverse field effects in nematic liquid crystals
Authors: Soref R.A.
Published: January 2004

A novel electro-optic effect has been observed in thin homeotropic nematic layers. Electrodes, such as a pair of parallel lines, are located on a planar surface in contact with the liquid. Deformation of the homeotropic ordering occurs when the applied field exceeds a threshold strength. Induced optical birefringence and diffraction have been observed, and electrically controlled optical transmission and reflection have been attained. Experimental data are given for a cyano-aniline mixture with ε∥ − ε⊥ > 0 and for negative-anisotropy materials.
Observation and explanation of multistable nonvolatile memory in silicon FIT diodes
Authors: Holm-Kennedy James W. , Heald David L. , Williams George , Chang Yu-Wen
Published: January 2004

Point-contact, Schottky, and diffused-silicon diodes doped with copper and iron impurities have been fabricated. These diodes show multistable behavior at room temperature, exhibiting a wide range of easily discriminated nonvolatile I-V rectifying characteristics (class I behavior). The class I behavior is explained in terms of field-induced trapping (FIT) with stationary space-charge domain formation in or near the depletion region. If the class I devices are treated by heating with a large current pulse-i.e., if they are formed-a second class (class II) of multistable behavior is observed. The class II behavior is also observed in Au-doped devices and is not presently well understood.
Energy and threshold characteristics of chemical lasers
Authors: Padrick T.D. , Gusinow M.A.
Published: January 2004

A comparative study has been made of the time sequencing and energy content of the HF laser transitions in the CH3I+N2F4 chemical laser with two different cavity configurations. In one case the cavity is made up of two mirrors, and in the other case of a mirror and a grating. The prime conclusion of this work is that in order to understand the threshold behavior and energy content of multitransition chemical lasers it is necessary to invoke some kind of wavelength-selective cavity. Furthermore, it has been observed that the use of a grating can channel a large portion of the normal total emission (obtained when the cavity consists of two mirrors) into a single transition.
Explanation of anomalous base regions in transistors
Authors: Fair Richard B.
Published: January 2004

The recent experimental results of Ziegler, Cole, and Baglin showed that in sequentially diffused boron-arsenic npn silicon transistors, an unexplained depletion of boron occurs near the emitter-base junction. This depletion effect could have an appreciable influence on transistor characteristics. A quantitative explanation is shown to exist, based upon the retarded base diffusion theory of Fair. The full-profile experimental results of Ziegler et al. are shown to be accurately described by solutions to the coupled As–B diffusion equations when the junction electric field effect and the vacancy undersaturation condition created by VsiAs2 complex formation are taken into account.
``Self''-demagnetizing effects in thermomagnetic writing on MnAlGe films
Authors: Wieder Harold , Burn Robert A.
Published: January 2004

During thermomagnetic writing on a film of MnAlGe, sequential cooling from the exterior to the interior of the laser-heated spot allows the periphery of the spot to achieve reverse magnetization before the interior of the spot has cooled significantly below the Curie point. This, in turn, produces a component to the demagnetizing field at the interior of the spot which opposes the normal demagnetizing field and which strongly affects the shape of the magnetization profile measured in this material.
Wavelength of the 3.39-μm laser-saturated absorption line of methane
Authors: Barger R.L. , Hall J.L.
Published: January 2004

The wavelength of the 3.39-μm line of methane has been measured with respect to the Kr86 6057-Å standard by using a frequency-controlled Fabry-Perot interferometer. We have exhaustively studied systematic offsets inherent in the experiment, including effects due to asymmetry of the Kr standard line. Lacking a convention relating the defined Kr wavelength 6057.802 105 Å to observables of the krypton line (e.g., center of gravity or fringe maximum intensity point), we report two methane wavelengths: λmax I=33 922.314 04 Å and λcg=33 922.313 76 Å. Both results have an uncertainty of δλ=±1.2×10−4 Å or δλ/λ=±3.5×10−9. Multiplication by the frequency measurement of the preceding letter gives the speed of light, ccg=299 792 456.2(1.1) m/sec.
Thermoelectricity in tungsten at low temperatures
Authors: Garland J.C.
Published: January 2004

Measurements of the thermoelectric properties of pure tungsten have been made between 1.2 and 7.0 K by a method in which the electric field within the metal was nulled by the simultaneous application of heat and electric currents. An unusual dependence of the thermoelectric properties on impurity concentration was observed below 3 K; these results are compared with conventional thermoelectric power measurements over the same range of temperatures.
Growth-induced magnetic anisotropy in Y2.4Eu0.6Ga1.2Fe3.8O12
Authors: Hagedorn F.B. , Blank S.L. , Barns R.L.
Published: January 2004

Torque magnetometer measurements on epitaxial magnetic garnet films of nominal composition Y2.4Eu0.6Ga1.2Fe3.8O12 have identified a growth-induced noncubic magnetic anisotropy of 8000 erg/cm3 which anneals away after several hours at 1300°C. Precision x-ray measurements show that the film lattice constant changes by not more than 0.0003 Å during this annealing process. These results are similar to previous observations made on epitaxial films of other compositions but are contrary to earlier reports of Geiss et al., Klokholm et al., and Cronemeyer et al. who had concluded that the noncubic anisotropy in Y–Eu films was exclusively stress induced and who reported large changes in film lattice constants with annealing.
The revealing of information concealed in overexposed x-ray topographs
Authors: Mardix S.
Published: January 2004

Thick photographic emulsions are used with weakly absorbed radiations. These emulsions are capable of photographic densities much higher than 1.5. High-density areas appear black, and photographic details are lost when viewed with transmitted light. Reflected-light techniques can reveal those details. Application to x-ray topography is demonstrated.
Nanosecond pulse amplification in electron-beam-pumped CO2 amplifiers
Authors: Figueira J.F. , Reichelt W.H. , Schappert G.T. , Stratton T.F. , Fenstermacher C.A.
Published: January 2004

Pulse amplification and energy extraction experiments in high-pressure CO2 amplifiers indicate that the effective rotational time constant for nanosecond energy extraction is an order of magnitude larger than the rotational relaxation time.
An ultrasonic technique for measuring the absolute signs of photoelastic coefficients and its application to fused silica and cadmium molybdate
Authors: Biegelsen D.K.
Published: January 2004

A simple dynamic technique for the determination of the absolute signs of photoelastic coefficients is described. The method consists of comparing the known phase of a standing acoustic wave with the phase of the deflection of a photoelastically refracted laser beam, the waist of which is small compared with an acoustic wavelength. Experimental verification of the technique is presented along with specific limitations. The method forms a convenient complement to the Bragg diffraction measurement of the magnitudes of photoelastic coefficients.
Photocurrent measurements on GaP : N green-light-emitting diodes
Authors: Kressel H. , Ladany I.
Published: January 2004

Photocurrent measurements are shown to provide a convenient technique for determining the nitrogen concentration in the active region of GaP diodes designed for green light emission. The strength of the photocurrent peak at the A-line energy can be correlated semiquantitatively with the diode efficiency in devices which differ only in their nitrogen content. Room-temperature photocurrent measurements of Schottky barrier diodes formed by gold evaporation on epitaxial material can be similarly used for determining the relative nitrogen concentration.
Minority-carrier lifetimes and luminescence efficiencies in nitrogen-doped GaP
Authors: Dapkus P.D. , Hackett W.H. , Lorimor O.G. , Kammlott G.W. , Haszko S.E.
Published: January 2004

Photoluminescence and scanning-electron-microscope measurements of minority-carrier lifetime and luminescence efficiency have been made on Zn, N-doped and Te, N-doped GaP liquid-phase-epitaxy layers. Nitrogen concentrations are held constant at 1 × 1019 cm−3, while the majority-carrier concentrations were varied between 5 × 1016 and 5 × 1018 cm−3. It is shown that, for excitation levels equivalent to 10 A/cm2 diode diffusion current density, a maximum external luminescence efficiency (in air) of 0.3% is measured for ∼1018-cm−3 Zn, N-doped GaP, in contrast to a maximum efficiency of 0.06% for ∼1017-cm−3 Te, N-doped GaP. These results suggest that significantly higher electroluminescent efficiencies approaching 0.3% are available for diodes at 10 A/cm2, by increasing injection into ∼1018-cm−3 Zn, N-doped GaP.
Voigt magnetoabsorption in semiconductors at low temperature
Authors: Srivastava G.P. , Kothari P.C.
Published: January 2004

A compensation bridge for measuring Voigt magnetoabsorption is set up for X band. Phase and amplitude measurements as a function of magnetic field are done on two n-type Ge crystals, having resistivities of 11. 9 and 4. 1 Ω cm at 89°K. The magnetic field is applied perpendicular to the direction of propagation and parallel to the microwave electric field (longitudinal case). Theoretical calculations are done by taking into account the mixed scatterings of lattice and impurities. The estimated values of the mobilities due to lattice scattering and impurity scattering are also presented.
Determination of the origin of the 10.6-μm absorption in CO2 laser window materials
Authors: Hardy J.R. , Agrawal B.S.
Published: January 2004

Theoretical studies are presented which show that it should be possible to determine whether the absorption at 10. 6 μm in alkali halides is due to impurities or whether it is intrinsic. These studies show that the temperature dependence of the measured absorption should be very different for intrinsic multiphonon absorption as compared with defect-activated absorption.
Performance of an unstable repetitive pulsed CO2 laser oscillator
Authors: Davit J. , Charles C.
Published: January 2004

Mode control experiments were performed with an unstable TEA repetitive pulsed CO2 laser oscillator. Near- and far-field intensity distributions were obtained that are consistent with theoretical values for a diffraction-limited beam. Performance of the same laser with a stable optical cavity is also given as a reference.
The extent of crystallization resulting from submicrosecond optical pulses on Te-based memory materials
Authors: von Gutfeld R. J.
Published: January 2004

Thermal profiles resulting from a laser-induced melt-quench cycle of a Te-based chalcogenide film on Mylar have been determined. These data are combined with experimentally obtained crystallization rates of Weiser et al. to determine the extent of crystallization that may occur in regions adjacent to the laser-produced amorphous region. A maximum fractional crystallization of less than 10−2 is found which indicates that no crystalline halo is expected to surround such an amorphous region. Thus, the extent to which photocrystallization plays a role in these alloy materials appears still to be an unanswered question.
Base-line noise reduction in laser pulse trains
Authors: Thorne James M. , Loree Thomas R. , McCall Gene H.
Published: January 2004

The intensity-dependent rotation of elliptically polarized light by carbon disulfide is used to discriminate against low-intensity laser light and pass high-intensity pulses through crossed polarizers. The transmitted intensity is shown to be proportional to the third power of the incident intensity. This technique has been used to reduce base-line noise and low-intensity pulses in the output pulse train of a mode-locked Nd : YAG oscillator.
The use of thermally stimulated ionic currents with a hyperbolic heating rate to measure sodium motion in rf-sputtered SiO2 films
Authors: Hickmott T.W.
Published: January 2004

Thermally stimulated ionic conductivity curves have been used to measure Na+ motion in rf-sputtered SiO2 films. A hyperbolic heating rate, 1/T=1/T0 - at, has been used to simplify data analysis. The energy for Na+ motion depends on bias voltage, on bias polarity, and on atomic defects in Si–SiO2–Al samples. Either Al positive or Al negative can be the direction of easy motion, depending on the nature of defects in the SiO2 film.
Photoemission from cesium-oxide-activated InGaAsP
Authors: James L.W. , Antypas G.A. , Moon R.L. , Edgecumbe J. , Bell R.L.
Published: January 2004

Zinc-doped InGaAsP quaternary III-V material of the proper composition range shows superior photoemission properties to either InGaAs or InAsP ternary material. The minority-carrier diffusion length in the quaternary material is at least as long as that in InAsP and much longer than observed in InGaAs. The barrier height at the InGaAsP–Cs2O interface is lowered by cooling, giving increased electron escape probability and new highs in quantum efficiency over a wide wavelength range. For example, a 1.06-μ quantum efficiency of 7.5%/incident photon was observed at − 90 °C.
Ultrafast optical Kerr effect in CS2 at 10.6 μm
Authors: Owen T.C. , Coleman L.W. , Burgess T.J.
Published: January 2004

This letter reports experiments that used a mode-locked TEA CO2 laser to modulate a cw He–Ne laser. This technique uses the optical Kerr effect in CS2. The optical Kerr coefficient, n2, at 10.6 μm is estimated from our data to be approximately 10−20 m2/V2.
Raman gain in glass optical waveguides
Authors: Stolen R. H. , Ippen E. P.
Published: January 2004

The small signal Raman gain in a single-mode glass waveguide amplifier has been measured directly. The measured gain is in good agreement with that calculated from the Raman cross section. The cross section was determined by a comparison of the spontaneous Raman scattering of fused quartz and benzene.
Direct observation of backscatter electron distributions on surfaces
Authors: Heidenreich R. D. , Thompson L. F.
Published: January 2004

The use of vinyl ferrocene monomer as a contaminating agent for the direct SEM observation of backscatter electron flux from target surfaces is described. The method readily yields a backscatter spatial current distribution as a function of radial distance r from the incident probe beam of the form JB(r) = exp(-br). A geometric backscatter model is suggested as an alternate to that of Archard and is shown to be in good agreement with experiment and Monte Carlo calculations.
Transverse discharge pulsed CO2 chemical transfer laser
Authors: Poehler T.O. , Walker R.E.
Published: January 2004

The exothermic chain reactions between deuterium and fluorine have been used to produce laser emission from carbon dioxide in a pulsed transfer laser. Stable mixtures of D2–F2–CO2–He were initiated by a transverse electrical discharge in a system with good chemical and electrical efficiency. Laser pulses at 10.6 μm from D2–F2–CO2–He mixtures at total pressure up to 250 Torr have been observed with energies up to 0.5 J.
Reflection loss of Rayleigh waves at cleaved edges in gallium arsenide
Authors: Haydl William H.
Published: January 2004

The reflection losses of Rayleigh surface waves incident at 90° to a cleaved edge have been measured in semi-insulating GaAs. The waves were propagating along the 〈110〉 direction on (100)-oriented wafers with (110)-cleaved surfaces. The reflection losses have been measured at 22, 38, and 72 MHz and were as low as 5 dB.
Charge-coupled device with buried channels under electrode gaps
Authors: Shimizu S. , Iwamatsu S. , Ono M.
Published: January 2004

A new kind of charge-coupled device with buried channels is described. This device is fabricated by forming ion-implanted buried channels under the gaps between electrodes. Since the device does not depend on the surface potential under the gaps, a reliable and low-operating-voltage device with nonoverlapping gate electrodes can be made. Transfer efficiency greater than 99.5% per transfer has been obtained at 500 kHz.
High-sensitivity transmission-mode GaAs photocathode
Authors: Gutierrez W.A. , Pommerrenig H.D.
Published: January 2004

A high-sensitivity negative-electron-affinity photocathode is reported which exhibits a luminous sensitivity of 330 μA/lm in transmission-mode operation. The structure and method of construction are described.
Optical Kerr effect in glass waveguide
Authors: Stolen R.H. , Ashkin A.
Published: January 2004

We have observed light induced birefringence in glass optical waveguide. This effect can be observed at low powers in waveguide because of the high power densities which are maintained over long lengths of guide. This effect is potentially useful as a wide-band pulse modulator or as a device for switching or measuring the length of picosecond pulses.
Magnetic field dependence of electrical conductivity for nonellipsoidal nonparabolic band structure
Authors: Wu Chhi-Chong , Tsai Jensan
Published: January 2004

Electrical conductivity for ultrasound propagating parallel to the dc magnetic field is calculated by using a quantum treatment which is valid at high frequencies. The energy band structure is assumed to be the Cohen nonellipsoidal nonparabolic (NENP) model. The results show that the ac longitudinal conductivity depends on the magnetic field, and some oscillations and discontinuities occur in the dependence of the conductivity on the magnetic field in the region of high frequencies and strong magnetic fields.
Violet luminescence of Mg-doped GaN
Authors: Maruska H.P. , Stevenson D.A. , Pankove J.I.
Published: January 2004

The photoluminescent and electroluminescent properties of GaN–GaN:Mg diodes are described. Visible violet electroluminescence was observed with excitation voltages of 10–20 V with the emission peak in the region of 2.9 eV. The I-V characteristics showed I ∞ V3 in the region where light was emitted, and the observed power efficiency was approximately 10−5. A photoluminescence peak at 2.9 eV provided additional evidence for an acceptor level, associated with the Mg impurity, about 0.5 eV above the valence band.
On the ultimate lower limit of attenuation in glass optical waveguides
Authors: Keck D.B. , Maurer R.D. , Schultz P.C.
Published: January 2004

The fabrication of an extremely-low-loss glass optical waveguide, having as little as 4 dB/km total attenuation, has allowed interpretation of the absorption spectrum to a much greater degree than previously possible. It is shown that, beyond about 700 nm, intrinsic ultraviolet absorption will have no effect. Between 700 and 1100 nm, all absorption can be accounted for on the basis of OH to within ±0.7 dB/km. Marked reduction of the water content will leave the scattering as the major loss mechanism, thereby permitting total attenuations of about 2 dB/km.
High-pressure calibration with a new absolute-pressure gauge
Authors: Ruoff Arthur L. , Lincoln R. C. , Chen Y. C.
Published: January 2004

Based on the simultaneous measurement of length and transit time of a specimen under pressure, we have developed a new way of determining absolute high pressure. The mercury freezing point at 0 °C has been determined with this new method at 7571.2±1.6 bar. Accurate high-pressure calibration of a secondary-pressure gauge such as a manganin gauge is possible with this method. The maximum deviation from linearity of the present gauge studied is 11.6±0.1 bar between atmospheric pressure and the mercury freezing point at 0 °C.
Charge diagnostics for electron-irradiated polymer foils
Authors: Gross B. , Sessler G.M. , West J.E.
Published: January 2004

Polymer foils carrying thin vacuum-deposited electrodes on both surfaces are irradiated with nonpenetrating monoenergetic electron beams of various energies. Measurement of the currents and charges drawn from both electrodes and of the voltage buildup between the electrodes during and after irradiation allows one to determine charge storage parameters of such electrets.
Noncollinear phase matching in GaAs
Authors: Aggarwal R.L. , Lax B. , Favrot G.
Published: January 2004

Noncollinear mixing in GaAs has been used to obtain phase-matched generation of the far-infrared difference-frequency radiation at 100.8 cm−1 with TEA CO2 lasers.
Amorphous metallic films for magneto-optic applications
Authors: Chaudhari P. , Cuomo J.J. , Gambino R.J.
Published: January 2004

It has been demonstrated that perpendicular uniaxial anisotropy and compensation points in the vicinity of room temperature can be obtained in amorphous thin films of rare-earth—transition-metal alloys. The magneto-optic properties of these films are reported, and it is shown that a remarkably good signal-to-noise ratio can be obtained in a thermomagnetically written film.
Hot-pressed CoCr2S4: a magneto-optical memory material
Authors: Ahrenkiel R.K. , Coburn T.J.
Published: January 2004

Hot-pressed CoCr2S4 has several properties which may be useful in a digital memory application. Among these are a large Kerr effect, a surface squareness ratio of about unity, and a transition temperature of 221 °K.
Tunable coherent ir source based upon four-wave parametric conversion in alkali metal vapors
Authors: Sorokin P.P. , Wynne J.J. , Lankard J.R.
Published: January 2004

A new type of near-ir source producing a coherent output with a spectrally narrow (∼ 0.1 cm−1) and continuously tunable frequency is described. It utilizes a four-wave mixing process in alkali metal vapor with input beams provided by two nitrogen-laser-pumped dye lasers. Tunable output has so far been observed in the range 2–5.4 μ.
p-type conduction in undoped ZnSe
Authors: Yu Phil Won , Park Y.S.
Published: January 2004

p-type conduction was observed from undoped ZnSe by heat treatment under a selenium atmosphere. Transport measurements are presented. Both shallow (∼ 0.1 eV) and deep (∼ 0.65–0.75 eV) acceptor levels are observed. It is proposed that a zinc vacancy or a zinc vacancy complex is a dominant mechanism in p-type conduction of ZnSe.
Relaxation rates of lower laser levels in CO2
Authors: DeTemple T.A. , Suhre D.R. , Coleman P.D.
Published: January 2004

The temporal decay of the laser pulse which occurs in the afterglow of a pulsed discharge in pure CO2 is shown to be controlled by the decay of the lower laser level. By varying the CO2 pressure, the relaxation rate of the 02°0 level was found to be ∼ 1.3 × 106/Torr sec. The 10°0 level was found to be governed by two decay rates: a fast rate, ∼ 1.7 × 106/Torr sec, and a slow rate, ∼ 1.7 × 105/Torr sec. These rates were unaffected by the presence of He and are attributed to the V–V equilibration processes within the ν1 and ν2 mode of CO2.
Green electroluminescence from CdS–CuGaS2 heterodiodes
Authors: Wagner Sigurd , Shay J.L. , Tell B. , Kasper H.M.
Published: January 2004

Heterodiodes have been prepared by vapor-deposition expitaxy of n-type CdS on p-type CuGaS2. Typical diodes emit green light under forward bias with external quantum efficiencies of 0.1% at 77 °K and 0.001% at room temperature. The radiative recombination results from electron injection into the CuGaS2.
On the reflections of normal-incidence Bleustein-Gulyaev surface waves
Authors: Pookaiyaudom S.
Published: January 2004

Analysis indicates a reflection coefficient of unity for Bleustein-Gulyaev surface waves normally incident upon a rectangular edge of a crystal of class C6v, having both the propagating surface and the end surface metallized.
Direct optical measurement of sodium hyperfine structure using a cw dye laser and an atomic beam
Authors: Schuda F. , Hercher M. , Stroud C.R.
Published: January 2004

A cw dye laser is described which allows short-term frequency stability of 10–15 MHz. An experiment using this laser to measure the hyperfine absorption spectrum of the sodium D2 line is described. Results from this experiment are presented showing a resolution of the F = 2 → 3 and the F = 2 → 2 transitions.
Semiconductor lasers pumped by pulsed electric discharge in vacuum
Authors: Nicoll F.H.
Published: January 2004

Lasing has been observed in several semiconductors pumped by electrons from a pulsed 5-to 20-kV vacuum arc. This method of pumping eliminates the hot-cathode multielement electron gun and magnetic focusing means usually required for electron-beam generation. At temperatures of 77 K and room temperature, CdS has shown well-defined lasing with narrow directional output and sharp spectral lines. CdSe and GaAs have shown similar evidence of lasing at 77 K. The new technique opens up some possibilities for simple compact laser devices.
Measurement of the V-V energy transfer rate from CO(v = 2) using tunable parametric oscillator excitation
Authors: Sackett Philip B. , Hordvik Audun , Schlossberg Howard
Published: January 2004

A parametric oscillator has been employed to pump ground-state carbon monoxide molecules in a gas-phase sample directly to the second vibrational level. The decay of the population of this level via vibration-vibration (V-V) energy transfer with ground-state molecules, CO(v = 2) + CO(v = 0) → CO(v = 1) + CO(v = 1), has been monitored as a function of pressure, resulting in the first experimental determination of the rate constant for this process, 6.2 × 104 sec−1 Torr−1 at 295 °K.
Laser operation of GaAs1−xPx:N (x = 0.37, 77 °K) on photopumped NN3 pair transitions
Authors: Dupuis R.D. , Holonyak N. , Lee M.H. , Campbell J.C. , Craford M.G. , Finn D. , Keune D.L.
Published: January 2004

Laser operation of GaAs1−xPx:N (x = 0.37, 77 °K) has been achieved by pumping the crystal below the fundamental energy gap on the NN3 transition. Photoluminescence experiments on the non-N-doped epitaxial GaAs1−xPx underlying the thin (≤ 25 μ) N-doped layer indicate that the absorption of He–Ne laser pump photons in GaAs1−xPx:N (x = 0.37) occurs only on the NN3 transition.
Electroabsorption in Aly Ga1−y As–Alx Ga1−x As double heterostructures
Authors: Reinhart F. K.
Published: January 2004

The electroabsorption observed in AlyGa1−yAs–Alx Ga1−xAs (y < x) double heterostructures is strongly polarization dependent. The absorption of the TM mode which is polarized parallel to the electric heterojunction field is larger than that of the TE mode. This dichroism increases with decreasing photon energy for photon energies smaller than the band-gap energy. The absorption is very large (up to 100 cm−1 for −10 V applied bias) for photon energies within 60 meV of the band gap. This electroabsorption effect can be used to make light intensity modulators, photodetectors, and polarizers. Very efficient intensity modulation has been demonstrated. The power necessary for 90% modulation is in the order of 0.1 mW/MHz.
Control of fixed charge at Si–SiO2 interface by oxidation-reduction treatments
Authors: Fowkes Frederick M. , Hess Dennis W.
Published: January 2004

Silicon dioxide films thermally grown on silicon have been reduced by exposure to low-oxygen-partial-pressure atmospheres in mixtures of CO and CO2 at 910 °C. After several hours an equilibrium oxide charge was observed at each oxygen partial pressure. Capacitance voltage measurements on the reduced samples have shown a large increase in the oxide's positive charge. The increase in charge resulting from reduction can be eliminated by exposing the samples to oxygen for 1 h. These findings suggest a relationship between the oxide charge and oxygen vacancies.
Auger analysis of chlorine in ``HCl- or Cl2-grown'' SiO2 films
Authors: Chou N.J. , Osburn C.M. , van der Meulen Y.J. , Hammer R.
Published: January 2004

Auger analysis of SiO2 films thermally grown in O2 in the presence of HCl or Cl2 shows that the incorporated Cl is unstable during the measurement. Cl profiling and mass-spectrometric sampling indicate that ionized Cl is transported in the electric field to the vacuum-oxide interface where it is desorbed by high-energy electrons. This instability restricts the usefulness of the Auger technique.
Asymmetric deformation in net zero strain fatigue of iron single crystals
Authors: Nine Harmon D.
Published: January 2004

Iron single crystals fatigued in torsion have shown asymmetric deformation. As the crystal samples are cycled in net zero strain, material is carried in only one circumferential direction over given sectors of the cylindrical sample surfaces. This effect is believed to be related to the asymmetry of slip on {112} and possibly {123} planes in body-centered-cubic (bcc) metals. Asymmetric deformation may be an important factor in fatigue of bcc metals because it results in much higher deformation per cycle than comparable cyclic loading in face-centered-cubic (fcc) metals.
Interferometric observations of kinetic cooling
Authors: Sica Louis
Published: January 2004

By using a three-beam interferometer, the time constant associated with kinetic cooling has been measured as a function of water vapor concentration in atmospheres of N2 with fixed CO2 concentrations in the 400- to 800-ppm range. Measurements have also been made in similar atmospheres with the addition of 10% O2. Least-squares fits to the data are consistent with theoretical predictions when extrapolated to zero water vapor concentration. When water vapor is important, however, the experimentally observed relaxation times are considerably shorter than the predicted times.
Defect photoconductivity of anodic Ta2 O5 films
Authors: Thomas J.H.
Published: January 2004

Photoconductive properties of anodic oxide films grown on β-Ta films have been measured at room temperature as a function of incident wavelength between 1000 and 500 nm (1.2–2.5 eV). Analysis of the spectral response of photoconductivity on thick (5200 Å) and thin (800 Å) oxides indicates the presence of a defect conduction band edge energetically at 1.5 eV below the oxide conduction band.
Focal spot size dependence of gas breakdown induced by particulate ionization
Authors: Canavan G.H. , Nielsen P.E.
Published: January 2004

The anomalous focal spot size dependence of breakdown threshold reported recently by Smith is interpreted as arising from the use of particulate contaminants as a source of ``preionizing'' microscopic plasmas in those experiments.
Cathodoluminescence study of plastically deformed GaAs
Authors: Esquivel A.L. , Lin W.N. , Wittry D.B.
Published: January 2004

Infrared cathodoluminescence (IR–CL) micrographs were taken of surfaces perpendicular (11¯2) and parallel (021) to the bend axis [11¯2] of GaAs single crystals bent at 700 °C in four-point bending to introduce α-Ga and β-As dislocations. At the bend center, light and dark checkered patterns associated with dislocations could be observed only in the IR–CL micrographs but not by optical, infrared, or secondary electron emission microscopy. Dislocation densities to ρ ≈ 5 × 106 cm−2 could be determined nondestructively to within 20% of the theoretical values. No significant changes related to the type of dislocation or dislocation density were observed either in the peak half-width or peak position at E = 1.411 eV. However, decreases of 40–70% in the relative IR–CL intensity were observed in the bent samples with predominantly α or β dislocations.
Population inversion calculations using near-resonant charge exchange as a pumping mechanism
Authors: Chubb Donald L. , Rose James R.
Published: January 2004

Theoretical results are presented for population inversions in a Ca–Xe system. Preliminary results show that it is possible to obtain inversions greater than 1014 m−3 with inversion times up to 8 × 10−7 sec. A possible charge-exchange laser system using an MPD arc plasma accelerator is also described.
Vacuum ultraviolet laser emission from C IV
Authors: Waynant Ronald W.
Published: January 2004

Laser emission from C IV resonance lines at 1548.2 and 1550.8 Å has been produced in a mirrorless traveling-wave transverse-discharge system. The gain of the 1-m-long device has been measured to be 8.7 dB/m, and the peak power is estimated to be a few kilowatts.
Wavelength dependence of the photoenhancement of nonlinear surface-wave convolution
Authors: Lim T.C. , Wolfram T. , Kraut E.A. , Sinha S.K.
Published: January 2004

The wavelength dependence of the photoenhancement of surface-wave convolution on piezoelectric ZnO exhibits peaks which correspond to the exciton transitions observed in optical reflectivity and absorption experiments. A possible model for ``exciton resonance enhancement'' of nonlinear elastic-wave interactions is proposed.
Deformation studies on BaTiO3 single crystals
Authors: Prasad V.C.S. , Subbarao E.C.
Published: January 2004

Compressive deformation studies on BaTiO3 single crystals show that the crystals deform easily at room temperature because of the movement of twin boundaries which are the 90° domain walls. In the twin-deformation region, the crystals exhibit time-dependent deformation, which could be observed as stress relaxation. Some features of this deformation and relaxation behavior are reported.
Anomalous electro-optic properties of ferroelectric strontium barium niobate and their device applications
Authors: Sakamoto Sadao , Yazaki Takehito
Published: January 2004

A longitudinal electro-optic memory effect is observed in ferroelectric single-crystal SrxBa1−xNb2O6 with tetragonal symmetry. The changeable birefringence depends on the remanent polarization of the crystal and can be switched by voltage pulses. These optical characteristics, which seem to be similar to the optical properties observed in ferroelectric Pb3MgNb2O9 with a diffuse phase transition, can be utilized in light-valve devices which operate in the longitudinal mode without a transverse electric field or strain bias.
Rayleigh wave guidance on LiNbO3
Authors: Coussot Gerard
Published: January 2004

A theoretical approach of Rayleigh wave guidance is presented by using a simple optical analogy. The propagating modes are determined versus the geometry of the nondispersive guidance structure by introducing a critical angle of reflection. Theoretical results are compared to the results of an experimental investigation on YZ LiNbO3 by using optical probing.
Population inversion in blast waves
Authors: Lee John H. , Bui T.D. , Knystautas R.
Published: January 2004

The present letter demonstrates that significant population inversion can be achieved in the flow structure behind a blast wave if appropriate choice of the initial parameters is made. Typical numerical results are given for a cylindrical blast from a line source in a CO2–N2–He medium. The predicted peak population inversion levels are an order of magnitude better when compared with those achieved in the more conventional gas-dynamic expansion systems using supersonic nozzles.
Singly resonant proustite parametric oscillator tuned from 1.22 to 8.5 μm
Authors: Hanna D.C. , Luther-Davies B. , Smith R.C.
Published: January 2004

A singly resonant parametric oscillator based on proustite has been operated for the first time. The device was pumped by a Q-switched neodymium (1.065 μm) laser in a noncollinear phase-matching geometry. The output has been tuned over the wavelength range 1.22–8.5 μm. The idler power was typically ∼100 W in a bandwidth of ∼1 cm−1.
Two-photon-excited stimulated recombination emission in InSb
Authors: Manlief S.K. , Palik E.D.
Published: January 2004

Two-photon-excited laser action in n-type InSb at T = 15 °K has been observed to occur at a threshold pumping intensity of 0.1 MW/cm2. The peak output power is estimated to be in excess of 20 mW. In a magnetic field, peaks in the laser output power are observed when twice the incident photon energy equals a Landau transition energy.
Heterodyne detection of frequency sweeping in the output of transverse-excitation CO2 lasers
Authors: Weiss Joel A. , Schnur Joel M.
Published: January 2004

Heterodyne detection is used to measure frequency sweeps in helical TE laser output. The heterodyne signal is analyzed and a model based on pressure-induced index-of-refraction changes is proposed.
Silicon-on-sapphire with microsecond carrier lifetimes
Authors: Schroder D.K. , Rai-Choudhury P.
Published: January 2004

The lifetime in silicon films epitaxially grown on sapphire is usually in the nanosecond range. We have recently succeeded in growing such silicon-on-sapphire (SOS) layers with lifetimes of several microseconds. These films were grown at 1025 °C by first forming an n+ film on sapphire followed by a moderately doped n layer. The heavily phosphorus-doped n+ layer appears to act as an effective getter and is the key to the high lifetime values.
Two-dimensional distributed-feedback lasers and their applications
Authors: Wang Shyh , Sheem Sang
Published: January 2004

We report the operation of two-dimensional distributed-feedback (DFB) lasers in which periodic thickness variations exist in two orthogonal directions in the plane of the film. By using photoresist and chemical etching, two-dimensional gratings with periods of 0.635 and 4.34 μm are formed on fused silica substrates. For the gain medium, a polyurethane film doped with rhodamine 6G is used. Emission characteristics and potential applications of two-dimensional DFB lasers are discussed.
Parametric studies on CO2 TEA lasers with extracavity and intracavity electrodes
Authors: Oettinger P.E.
Published: January 2004

Measurements were made of power output from a 1-m resistance-limited CO2 TEA laser with changing electrode configuration and spacing, mirror curvature, gas composition and pressure, and applied voltage. A maximum power of 20 MW was emitted from an extracavity plane-parallel pin-plate oscillator with a 4-cm electrode separation. An intracavity concentric electrode system with equal diameter yielded 1.4 MW.
Study of self-focusing damage in a high-power Nd: glass-rod amplifier
Authors: Fleck J.A. , Layne C.
Published: January 2004

Self-focusing damage in a pattern of Fresnel fringes is observed in the final element of a high-power glass laser amplifier as the result of the truncation of a Gaussian input beam. Detailed calculations give good agreement with the location and pattern of damage.
Interpretation of Pt3Co FIM images as investigated with an atom probe
Authors: Tsong T. T. , Krishnaswamy S. V. , McLane S. B. , Müller E. W.
Published: January 2004

Cobalt atoms in ordered Pt–Co alloys are not imaged in the field ion microscope, although in the lattice the Co atoms occupy sites equivalent to those of the Pt atoms. Using the atom-probe FIM, we show that the invisibility of the Co atoms in Pt3Co is caused by selective field ionization of the image gas above Pt atoms only, rather than by the absence of Co atoms in the surface by preferential field evaporation.
Experimental confirmation of the Fowler-Nordheim law for large-area field emitter arrays
Authors: Schroder D. K. , Thomas R. N.
Published: January 2004

It is well known that single field emitters obey the Fowler-Nordheim (F-N) relationship. We show here that large-area emitters, with as many as 106 emitters participating in the emission process, also obey the F-N law, giving straight lines on such plots.
Plasma heating by an intense relativistic electron beam
Authors: Kapetanakos C. A. , Hammer D. A.
Published: January 2004

A 400-keV 40-kA 50-nsec-duration relativistic electron beam is injected into a plasma confined in a magnetic mirror. It is found that the coupling efficiency of beam energy into the plasma at fixed magnetic field is optimum when the beam and plasma densities are comparable, and is independent of magnetic field, provided it exceeds 2.5 kG.
Laser diffraction of brittle polymer under tension
Authors: Hsiao C. C.
Published: January 2004

Laser diffraction technique has revealed interesting and useful information when crazing and cracking occur in a stressed polymer. Based on preliminary results, their distribution and geometry may be determined quantitatively.
Excitation of vacuum ultraviolet emission from high-pressure xenon by relativistic electron beams
Authors: Wallace Stephen C. , Hodgson R. T. , Dreyfus R. W.
Published: January 2004

This letter reports an investigation of the vacuum ultraviolet emission from gaseous xenon excited with a 4-nsec 10-kA cm−2 electron beam. The observed decrease in the emission lifetime at 171.5 nm for high xenon number density is due to a quenching process intrinsic to xenon. Treatment of the quenching data yields a radiative lifetime of 130 ± 20 nsec for the excited xenon diatomic, and a quenching constant of 5.1 × 10−13 cm3 atom−1 sec−1. Thus, the theoretical threshold for laser action in excited diatomic xenon molecules is ∼ 26 times higher than had been previously anticipated from the 5-nsec lifetime observed in liquid xenon.
High-power narrow-linewidth operation of GaAs diode lasers
Authors: Rossi J. A. , Chinn S. R. , Heckscher H.
Published: January 2004

By utilizing a dispersive element in an external cavity, we find it possible for pulsed room-temperature GaAs diodes to emit high output power (3 W) into a narrow linewidth (0.4 Å). This narrow-band output is continuously tunable over an ∼ 100-Å range with only a moderate variation in output power. Significantly, these qualities are preserved even at high output power densities (3 × 106 W/cm2).
Conditions for laser oscillations in distributed-feedback waveguides
Authors: DeWames R. E. , Hall W. F.
Published: January 2004

An analysis of laser action in a waveguide configuration with a bulk periodic complex index variation or a corrugated surface structure is presented. Simple analytical expressions are obtained for the effective gain parameter per unit length and the coupling constant which measures the degree of feedback. Our results are compared with the recent work of Kogelnik and Shank as well as that of Wang.
Time-dependent breakdown of silicon dioxide films
Authors: Raider S. I.
Published: January 2004

Na ion drift through intentionally contaminated SiO2 films is observed at room temperature when voltages of the appropriate polarity are applied across the oxide. Enhanced electronic conduction and time-dependent breakdowns of Al/SiO2/Si capacitors electrically stressed at constant field strengths were correlated with this Na ion drift. The applied field strengths, E, and times, t, to breakdown of contaminated capacitors were found to be linearly related by Peek's law, in which E ≈ t−1/4.
Holography of large objects in a turbulent atmosphere with a cw laser
Authors: Cain D. A. , Billings C. , Johnson C. D. , Mayer G. M.
Published: January 2004

Results of tests of long-range large-object holography in a turbulent atmosphere are presented. Photographs of holograms of static and vibrating objects as large as 12 × 28 ft and at distances up to 160 ft are shown. The light source for these holograms was an argon-ion cw laser. The medium was air with 5- to 10-mph winds over an irregular surface.
Surface wave correlator via space charge nonlinearity
Authors: Drukier I. , Wang W. C. , Das P.
Published: January 2004

The interaction of an acoustic surface wave, propagating in a piezoelectric substrate, with an electric (pump) field induced in a nearby semiconductor produces an acoustic wave which is the correlation of the pump and surface wave signals. The theory of the interaction and experimental verification of the theoretical predictions are presented.
An explanation for the Bekefi peaks in the low-field microwave emission from InSb
Authors: Niederer H. H. J. M. , van Welzenis R. G.
Published: January 2004

The peaks in the microwave emission intensity from InSb, at 4.2 K, observed at distinct values of the applied magnetic field as reported by Bekefi et al., are explained in terms of magnetophonon resonances in the acoustoelectric amplification.
Thermal blooming of pulsed laser radiation
Authors: Kleiman H. , O'Neil R. W.
Published: January 2004

We have observed thermal blooming of focused 1.06-μ pulsed laser radiation propagating in a weakly absorbing medium. Laser pulse lengths of 3–100 μsec were used to span the hydrodynamic time, which is defined as the pressure disturbance transit time across the laser beam. One-dimensional eikonal models of laser propagation in the limits of pulse duration less than the hydrodynamic time and pulse duration greater than the hydrodynamic time agree well with the experimental results.
Spectral losses of unclad fibers made from high-grade vitreous silica
Authors: Kaiser P.
Published: January 2004

Spectral loss measurements performed between 0.5 and 1.15 μm with up to 32-m-long unclad fibers drawn from Suprasil W1, Spectrosil WF, and Corning 7943 synthetic vitreous silica demonstrated that bulk glasses with total losses well below 10 dB/km at certain wavelengths of interest for future optical communication systems are already commercially available. Lowest losses of 4 dB/km at 0.90 μm and 2.5 dB/km at 1.06 μm were obtained with one of the samples evaluated.
Tunable far-infrared generation by difference frequency mixing of dye lasers in reduced (black) lithium niobate
Authors: Auston D. H. , Glass A. M. , LeFur P.
Published: January 2004

Continuously tunable far-infrared radiation from 2 to 50 cm−1 has been generated in lithium niobate which was reduced in a H2, N2 atmosphere to render it highly absorbing. The efficiency of far-infrared generation by optical excitation of absorbing defects compares favorably with generation by the electro-optic effect in clear LiNbO3. Output powers of a few milliwatts were obtained without phase matching.
Acceptor profiles obtained by diffusive redistribution of implanted impurities during annealing
Authors: Gibbons James F.
Published: January 2004

Damage-enhanced diffusion and annealing is examined as a means for producing the observed redistribution of boron that is implanted into Si at 77 °K and then annealed at 650 °C. A model incorporating spatial variation of both the diffusion coefficient and the final electrical activity is found to fit the experimental data with reasonable accuracy.