bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical nonlinearities in conjugated systems: β-carotene
Authors: Hermann J. P. , Ricard D. , Ducuing J.
Published: January 2004

Quantitative studies of third-harmonic generation in the all-trans β-carotene molecule and of third-harmonic generation and the optical Kerr effect in β-carotene glass are reported. The large values of the optical nonlinearities are attributed to the broadly delocalized Π electrons.
Continuous operation of GaAs–Ga1 − xAlxAs double-heterostructure lasers with 30 °C half-lives exceeding 1000 h
Authors: Hartman R. L. , Dyment J. C. , Hwang C. J. , Kuhn M.
Published: January 2004

This paper reports the first continuous operation of GaAs–Ga1 − xAlxAs double-heterostructure (DH) junction lasers for periods of time in excess of 1000 h in a 30 °C ambient. One laser which has operated at a constant direct current for more than 1000 h has degraded only 10% from its initial 20-mW light output. At 1000 h, the differential quantum efficiency remained essentially unchanged, but the threshold and the mode structure changed appreciably.
Properties of chalcogenide glass-silicon heterojunctions
Authors: Reinhard D. K. , Arntz F. O. , Adler D.
Published: January 2004

The properties of heterojunctions between n- and p-type crystalline silicon and certain threshold-type amorphous chalcogenide films have been investigated. Low-field and high-field I-V characteristics, switching properties, and photoelectric behavior have all been studied. Devices fabricated with silicon substrates of opposite types are distinctly different; device characteristics at low voltages were found to be influenced appreciably by interface states. Short-circuit photocurrent data imply band models which explain the I-V properties in both the absence and the presence of light.
Growth of LiNbO3 single-crystal film for optical waveguides
Authors: Miyazawa Shintaro
Published: January 2004

Ferroelectric LiNbO3 single-crystal film was successfully grown onto a LiTaO3 substrate by a new method, epitaxial-growth-by-melting (EGM) method. The propagation of a He–Ne laser beam fed into the film was demonstrated. Some preliminary results of this new technique for fabricating optical waveguides are reported.
Molecular beam epitaxy of alternating metal-semiconductor films
Authors: Ludeke R. , Chang L. L. , Esaki L.
Published: January 2004

Epitaxial growth of alternating thin films of GaAs and Al was achieved on GaAs substrates of various orientations. In situ high-energy electron diffraction (HEED) analysis was used to monitor the molecular beam growth process. The following crystallographic relationship was observed: (100) GaAs on (110) Al on (100) GaAs substrates, with [110] GaAs parallel to [100] Al. An atomic interface model is proposed to explain the observed growth.
Lifetime characterization of propagated bubble-data streams
Authors: Shumate P. W. , Peirce R. J.
Published: January 2004

A ``mean-time-to-failure'' measurement has been made on propagated magnetic bubble domain patterns. A Permalloy T-bar field-accessed circuit was used with two compositions of epitaxially grown magnetic garnet films. As the number of steps of propagation at 100 kHz increases, the bias field margins at constant drive field for error-free propagation are observed to decrease. A reasonable extrapolation of the data taken on a specific circuit-material combination operated near the center of the bias range at 100 kHz suggests that an error rate as low as 10−20 per step is attainable. The effects of the circuit-to-garnet spacing and drive field magnitude are discussed, as well as the effects of ion implantation and crystal annealing.
Stability of liquid charged electrets
Authors: Chudleigh P. W. , Collins R. E. , Hancock G. D.
Published: January 2004

Stability measurements on liquid charged Teflon FEP electrets are reported. The initial decay is nonexponential and strongly dependent on experimental conditions, while the long-term decay is dependent on foil material and temperature. However, in all cases, there appears to be a single rate-limiting process with a measured activation energy equal to 1.9 ± 0.1 eV.
Single-crystal growth and piezoelectric properties of lead potassium niobate
Authors: Yamada Tomoaki
Published: January 2004

Large single crystals of lead potassium niobate were grown by the method of pulling from a melt, and their piezoelectric properties were preliminarily investigated. The crystals have ferroelectric tungsten bronze structure with a Curie point of about 460°C. Spontaneous polarization lies perpendicular to the c axis as in ferroelectric PbNb2O6. Particularly large electromechanical coupling factors were measured; i.e., 0.69 ± 0.03, 0.73 ± 0.03, and 0.59 ± 0.01 for k15, k24, and kt, respectively. Temperature coefficients of the fundamental resonant frequencies in y- and z-cut plates were found to be <30 ppm around room temperature.
Evidence that the minimum-energy state is not accessible to a system of droplets produced by electrohydrodynamic spraying
Authors: Krohn V. E.
Published: January 2004

A number of arguments are presented to demonstrate that the minimum-energy state is not accessible to a system of droplets produced by electrohydrodynamic spraying.
Doppler ambiguity in laser Doppler velocimeters
Authors: George W. K. , Berman N. S.
Published: January 2004

An analysis of the Doppler ambiguity for the laser Doppler velocimeter is presented which accounts for the signal statistics based on a Gaussian beam intensity. Results are in excellent agreement with experiment.
CdSnP2–InP heterodiodes for near-infrared light-emitting diodes and photovoltaic detectors
Authors: Shay J. L. , Bachmann K. J. , Buehler E. , Wernick J. H.
Published: January 2004

Heterodiodes have been prepared by liquid-phase epitaxy of n-type CdSnP2 from Sn solution onto p-type InP. Electroluminescence is observed near 1.4 μ with internal quantum efficiencies of 10% at 77°K and 1% at room temperature. The photovoltaic response of typical diodes shows moderate quantum efficiencies (4–12%) in the near infrared (1.2–1.0 μ).
Stimulated emission in multiple-photon-pumped xenon and argon excimers
Authors: Harris S. E. , Kung A. H. , Stappaerts E. A. , Young J. F.
Published: January 2004

Multiple photon absorption of laser radiation at 2660 and 3547 Å is used to pump excimers of Xe and Ar. Line narrowing is observed in bands ∼ 100 Å wide, centered at 1730 and 1260 Å, respectively.
Miniature diode-pumped Nd : YAIG lasers
Authors: Chesler R. B. , Draegert D. A.
Published: January 2004

A miniaturized Nd : YAIG laser is described, in which a 5 × 0.45-mm laser rod is end pumped by a single incoherent GaAs1−xPx light-emitting diode. Laser threshold was achieved at room temperature in a pulse pumped mode of operation. The measured threshold optical power incident on the end of the laser rod was 19 mW at 24°C. Based on an extrapolation from known Ga1−xAlxAs diode performance, it is concluded that present technology can provide diode pumps to drive a miniature Nd : YAIG laser 2.4 times above threshold continuously at room temperature.
Attenuation properties of optical waveguides with a metal boundary
Authors: Reisinger A.
Published: January 2004

Attenuation coefficients have been measured at 6328 Å in liquid waveguides bounded on one side by a metal wall. Provided that the measurements be made on selected samples meeting certain criterions, Ohmic boundary absorption is found to depend on mode order N as (N + 1)2 and waveguide thickness w as w−3, in agreement with theory.
On the possibility of measuring gas concentrations by stimulated anti-Stokes scattering
Authors: Régnier P. R. , Taran J. P.-E.
Published: January 2004

A novel and very sensitive method for gas concentration measurements is proposed. Intense light scattering is obtained through a stimulated interaction. The method appears more practical than spontaneous Raman scattering for gas flow analysis with fine spatial resolution. Experimental results with the detection of H2 are given.
Observations of stimulated emission from high-pressure krypton and argon/xenon mixtures
Authors: Hoff Paul W. , Swingle James C. , Rhodes Charles K.
Published: January 2004

Experimental data demonstrating coherent oscillation in high-pressure krypton at 1457 ± 1 Å with an 8-Å linewidth are reported. Observations of stimulated emission from argon/xenon mixtures arising from the operation of efficient energy transfer processes and resulting in a twofold enhancement of the xenon laser output at ∼ 1720 Å are also given. The influence of collisional-induced absorption on the oscillator output is indicated by the measurement of a blue shift in the spectrum of the stimulated output for argon/xenon mixtures relative to the case of pure xenon.
Simultaneous multiple-wavelength operation of a tunable dye laser
Authors: Friesem A. A. , Ganiel U. , Neumann G.
Published: January 2004

A new technique for simultaneous operation of a dye laser at a number of independently tunable wavelengths is described. The system utilizes holographic wavelength selectors in succession, each aligned to choose one particular wavelength, and the output beam contains these wavelengths collinearly. Strong competition effects due to the homogeneous broadening of the amplifying medium reduce the multiple-wavelength tuning range. By proper adjustment of the components in the device, this range can be increased to cover most of the single-wavelength tuning region. The operational characteristics and the experimental results obtained at two-wavelength operation are presented and discussed.
Waveguide laser for the far infrared (FIR) pumped by a CO2 laser
Authors: Hodges D. T. , Hartwick T. S.
Published: January 2004

Using a hollow waveguide resonator, laser operation in the far infrared (FIR) has been observed on several transitions between 40 and 200 μm from methyl alcohol excited by the resonant absorption of CO2 pump laser lines. The preliminary performance characteristics of FIR waveguide lasers constructed from both metallic and dielectric tubes are discussed. For CO2 pump powers of a few watts, cw output power at the milliwatt level in the FIR was observed from waveguide laser structures only a small fraction of the size of conventional FIR laser resonators.
Time delays in external-cavity-controlled GaAs/GaxAl1−xAs single-heterostructure diode lasers
Authors: Rossi J. A. , Heckscher H. , Stillman G. E. , Chinn S. R.
Published: January 2004

By using a wavelength-selective external cavity, the time delay and Q-switching effects commonly observed in homojunction and single-heterostructure diodes are shown to be strongly dependent on the lasing wavelength. The data suggest that the energy distribution of injected electrons as a function of time is an important factor in determining the diode delay behavior.
Primary oxygen ion implantation effects on depth profiles by secondary ion emission mass spectrometry
Authors: Lewis R. K. , Morabito J. M. , Tsai J. C. C.
Published: January 2004

Both adsorbed reacted surface oxygen (surface oxide) and the dynamic implantation range of primary oxygen ions have been shown to influence secondary ion yields and complicate the interpretation of secondary ion mass spectrometry (SIMS) in-depth analysis within the first few hundred angstroms of the surface. Surface oxide chemically enhances the secondary ion yield over the first few tens of angstroms. After removal of the surface oxide, the secondary ion emission yield reaches a minimum level, and enhancement of the secondary ion yield is then a function of the distribution of the implanted oxygen concentration. These effects have been studied on arsenic-implant-diffused and unimplanted single-crystal silicon.
A new method for the determination of the interface-state density in the presence of statistical fluctuations of the surface potential
Authors: Baccarani G. , Severi M. , Soncini G.
Published: January 2004

A new method for the analysis of the high- and low-frequency MOS C–V characteristics is proposed to determine the interface-state density in the presence of statistical fluctuations of the surface potential. This method provides simultaneously the mean oxide charge and the variance of its Gaussian distribution.
Anomalous residual damage in Si after annealing of ``through-oxide'' arsenic implantations
Authors: Cass T. R. , Reddi V. G. K.
Published: January 2004

During a study of the annealing of damage produced by high-dose (1015–1016 ions/cm2) arsenic implantations into Si, a stable high-defect-density structure was observed. It resulted from implantations through thin SiO2 films covering the Si. Formation of the stable defect structure is related to the presence of the SiO2 film during implantation, but not during annealing. Subsequent experiments indicate that knock-on of oxygen by the As ions is not directly responsible for the effect.
Trapped plasma triggered by carrier injection
Authors: Kawamoto H.
Published: January 2004

A trapped plasma, dense electron-hole pairs trapped in a semiconductor p+-n-n+ structure, conventionally has been triggered by applying overdriven electrical fields to initiate impact ionization. In this letter it is shown that the trapped plasma also can be triggered by injecting electrons while electrical fields are held just below the critical level. In this new triggering mode, the injected electrons multiplied by impact ionization locally raise the electrical field, which thus further excites the impact ionization.
High-quantum-efficiency infrared up-conversion
Authors: Gurski Thomas R.
Published: January 2004

We report 100% conversion of infrared photons into visible photons through three wave interactions in a nonlinear medium, present the first experimental evidence of overconversion, and confirm the classical theory of up-conversion in the high-conversion-efficiency region. A laser pump light feedback technique is described that promises to make the process practical with modestly powerful pump lasers and less than perfect nonlinear crystals. The nonlinear medium used was a LiIO3 crystal that cannot be 90° phase matched. The ``walk off'' that resulted helped make possible the attainment of 100% conversion efficiency.
Processing and properties of superconducting V3Ga composites
Authors: Howe D. G. , Weinman L. S. , Meussner R. A.
Published: January 2004

A processing technique to form V3Ga in composite wires of V and a Cu-15.4 at. % Ga alloy is outlined. The structure sensitivity of the superconducting properties of V3Ga are demonstrated through quenching curve data. Improved Jc(H) properties are obtained with decreasing reaction temperatures, superconducting layer thickness, and wire core diameter.
High-resolution Hgl2 x-ray spectrometers
Authors: Swierkowski S. P. , Armantrout G. A. , Wichner R.
Published: January 2004

Several high-resolution HgI2 x-ray detectors have been made from single crystals grown from the vapor phase. Hole and electron transport properties and detector electrical characteristics are described. Measured mobility-lifetime product for electrons is 8×10−5 cm2/V with a μe of 3 cm2/V sec. The mean energy per electron-hole pair is 4.33 eV at 122 keV. Detectors up to 1 mm3 are described, and a resolution as low as 850 eV at 300 °K in air has been obtained for 5.9-keV x rays, which suggests possible x-ray flourescence detection applications.
Orientation dependence of blister shape in niobium monocrystals implanted with channeled helium ions
Authors: Kaminsky M. , Das S. K.
Published: January 2004

The shape, size, and orientation of blisters formed on the (111), (110), and (001) surface planes of monocrystalline niobium samples irradiated at 900°C with 0.5-MeV channeled 4He+ ions have been studied. The results indicate a strong dependence of (a) the blister shape and (b) the orientation of the blisters with respect to each other on the crystallographic orientation of the target. Both observations can be related to the intersection of certain active slip planes with the surface plane of the monocrystal during blister formation. This interpretation elucidates our recently reported anomaly in the alignment of the blisters on Nb (111) planes.
Parametric coupling of bulk acoustic waves at surface interdigital transducers
Authors: Vella P. J. , Stegeman G. I. A.
Published: January 2004

Acoustic radiation by interdigital transducers on yz LiNbO3 has been studied experimentally in the region of strong longitudinal bulk wave generation. The measured relative intensity of the transducer first and second spatial harmonics and the number and type of acoustic modes generated establish the existence of acoustic generation by parametric periodic coupling.
A practical p-n junction cold cathode
Authors: Faulkner K. R. , Astridge R. A. , Howorth J. R. , Surridge R. K.
Published: January 2004

A GaAsP p-n junction negative-electron-affinity cold cathode is described which exhibits adequate stability and life for practical image tube applications. Emission characteristics have been studied in sealed-off systems to determine stability, angular distribution, and uniformity.
Self-induced transparency with CO2 laser pulses in ammonia gas
Authors: David C. D. , Clark W. M.
Published: January 2004

Self-induced transparency effects, namely pulse delay and nonlinear transmission, are observed at two CO2 laser line and Stark-tuned NH3 absorber transition resonances; these are the P(32) CO2 laser line and the asQ(5, 3, 5) NH3 transition with a Stark field of 12.3 kV/cm at 10.7 μm and the R(6) CO2 laser line and the saQ(5, 5, 5) NH3 tuned with a 14.6-kV/cm field at 10.3 μm.
Continuous pulse train dye laser using an open flowing passive absorber
Authors: Letouzey J. P. , Sari S. O.
Published: January 2004

Operation of a cw Ar+-pumped rhodamine 6G laser tunable over 900 Å is reported using a thin flowing dye sheet in a new configuration. Passive mode-locked operation tunable over 400 Å has been obtained using an open flowing sheet of DODCI absorber. Multiple-pulse propagation in the laser cavity is observed with increasing pump power above threshold.
Electron spin relaxation measurements by optical pumping techniques
Authors: Huberman B. A. , Scifres D. R. , Burnham R. D.
Published: January 2004

A new method for measuring the spin relaxation time of conduction electrons in semiconductors which requires no external magnetic field is presented. It relies on the photoproduction of spin-polarized electrons and a measurement of their radiative recombination time by optical pulse techniques. Results on GaAsP at 77°K are presented and applications are discussed.
High-field transport properties of aluminum-embedded aluminum oxide films
Authors: Birey Hülyâ
Published: January 2004

Current-voltage characteristics of aluminum-embedded aluminum oxide thin films with Al or Au electrodes, between 150–1000 Å in thickness, prepared by thermic evaporation of pure aluminum in partial air pressure are studied. I-V characteristics of these films showed metallic conductivity, switching, and memory effects different than those observed in amorphous materials, and metal-oxide-metal diode characteristics as the amount of metallic aluminum within the oxide is decreased in respective samples. The switching and memory effects are found to be independent of oxide thickness and electrode material.
Rotational relaxation effects in short-pulse CO2 amplifiers
Authors: Schappert G. T.
Published: January 2004

On the basis of a rate equation model, it is shown that the time constant for short-pulse energy extraction from all rotational levels in a CO2 amplifier on a single P(J) or R(J) transition is larger than the rotational relaxation time by about 1/κ(J,T), where κ(J,T) is the partition fraction of the transition levels at the temperature T.
Gain in DTTC-methanol solution as a function of pump power, wavelength, and time
Authors: Gillard P. G. , Foltz N. D. , Cho C. W.
Published: January 2004

The single-pass gain of a 4 × 10−5 M/l solution of 3,3′-diethylthiatricarbocyanine iodide in methanol optically pumped by a giant-pulse ruby laser was measured as a function of pump power, wavelength, and time. Pump power was varied over a range of 0–7 MW and the wavelength range was 7850–8075 Å. The gain is seen to have strong dependence on the instantaneous pump power. The dependence of gain on pump power is plotted from the experimental data for six wavelengths in the region investigated, and is also discussed theoretically. The spontaneous decay rate from the excited state and the cross section for stimulated emission are also obtained from the theory. The low signal gain coefficient and the gain saturation value are tabulated for each wavelength investigated.
Modes in optical waveguides formed by diffusion
Authors: Conwell Esther M.
Published: January 2004

For an optical guide with index of refraction having a small exponential variation superimposed on a constant background value, such as is found in guides made by diffusing Se into CdS, the wave equation may be solved exactly. The solutions and characteristic equations for determining the possible TE and TM modes are given and the properties of the modes are discussed.
Current-voltage characteristics of p-Ge/n-CdS heterojunction diodes
Authors: Duncan W. , Lamb J. , McIntosh K. G. , Smellie A. R.
Published: January 2004

The current-voltage characteristics of p-Ge/n-CdS heterojunction diodes have been studied for a wide range of diodes fabricated under different CdS film growth conditions. It has been found that under certain growth conditions the diodes possess two resistance states: Switching from the high- to low-resistance state occurs with a small reverse-bias voltage, while switching from the low- to high-resistance state occurs with a small forward-bias voltage. Measurements have been carried out on the junction capacitance, and it has been found that the capacitance increases when the diode is switched to the low-resistance state and reverts to its initial value when the diode is switched back to the high-resistance state. It is concluded that the two resistance states of the diode are associated with a junction phenomenon and not with some change in the physical state of the n-type film. A prerequisite for this behavior would appear to be that the dielectric relaxation time should be greater than the diffusion lifetime.
Measurement of the 10°0–02°0 relaxation rate in CO2
Authors: Stark E. E.
Published: January 2004

The small-signal gain on the 9- and 10-μ bands of CO2 is monitored in a portion of an amplifier during and after the passage of a saturating pulse. The 10°0–02°0 relaxation rate is inferred from this experiment, and a resolution of conflicting previous measurements of this and other rates is offered.
Low-loss fused silica optical waveguide with borosilicate cladding
Authors: French William G. , Pearson A. David , Tasker G. William , MacChesney John B.
Published: January 2004

Optical waveguides consisting of a pure fused silica core and borosilicate cladding were produced by using chemical vapor deposition techniques. A typical guide showed an optical attenuation of 7.5 ± 1.5 dB/km, measured at 0.63 μm (He–Ne laser). In one of the guides whose loss spectrum was studied, the attenuation was less than 20 dB/km between 0.55 and 0.86 μm except for the third OH overtone at ∼ 0.72 μm. The lowest loss of this waveguide occurred at 0.80 μm, with other minima at 0.66 and 1.06 μm.
Low-loss silica core-borosilicate clad fiber optical waveguide
Authors: MacChesney J. B. , Jaeger R. E. , Pinnow D. A. , Ostermayer F. W. , Rich T. C. , Van Uitert L. G.
Published: January 2004

A low-loss fiber optical waveguide has been constructed having a pure fused silica core of 40-μm diameter and a chemical-vapor-deposited cladding layer of borosilicate glass 15–20 μm thick. This core-clad structure has an outer jacket of fused silica which serves to strengthen and protect the waveguide. Fabrication procedures and evaluation techniques are described. One fiber has been found to have a minimum optical attenuation of 13 dB/km at a wavelength of 0.7 μm. In the range 0.8–1.1 μm, where optical communications appear most promising, the attenuation varies between 18 and 22 dB/km with the exception of the OH absorption peak at 0.95 μm.
On the anomalous generation of neutrons in laser plasmas
Authors: Katz J. I.
Published: January 2004

A nonthermal beam-target model is proposed to explain the anomalous generation of neutrons from laser plasmas. The model requires the presence of a multimicrosecond prepulse that generates an extended low-density gas cloud, and it predicts the effects of the addition of a background gas to the experiments.
Superconducting thin-film quantum galvanometer
Authors: Decker S. K. , Mercereau J. E.
Published: January 2004

A refractory metal thin-film superconducting quantum galvanometer with a sensitivity of nearly 10−9 A has been developed. Design and construction are discussed and a model of finite-voltage operation of the galvanometer is presented.
A novel parametric negative-resistance effect in Josephson junctions
Authors: Kanter H.
Published: January 2004

The negative-resistance effect recently predicted for current-controlled highly damped Josephson junctions is experimentally demonstrated at a frequency of 9 GHz. Characteristically, the pump (or Josephson) frequency is smaller than the amplified one, and the pump mechanism is effective over a broad range of frequencies in contrast to the conventional parametric negative-resistance effect where the pump frequency exceeds that of signal and idler and where the frequency of operation is limited to a narrow range. The broad-band feature renders operation uncritical to tuning and bias voltage fluctuations. The fact that the junction is the element of lowest impedance in the circuit alleviates to a degree the matching problem generally encountered with Josephson contacts.
Frequency and temperature dependence of ultrasonic attenuation in glassy Pd–Si-based metal alloys
Authors: Dutoit M. , Chen H. S.
Published: January 2004

The frequency and temperature dependence of the ultrasonic attenuation in glassy Pd–Si-based alloys has been measured. In all compositions, the room-temperature attenuation varies as the square of frequency. A remarkably low loss of 0.06 dB/μsec at 100 MHz for longitudinal waves is observed in alloys containing silver, a loss equal to the lowest value reported for fused silica. Below 300 K, the attenuation in Pd0.775Ag0.06Si0.165 shows a broad peak at about 25 K. This behavior is similar to that noted in chalcogenide glasses. The estimated electronic contribution to attenuation is too small to account for measured values. Present data are insufficient to ascertain what causes this relaxation peak. It may be related to the excess specific heat previously observed in these alloys at low temperatures.
Kikuchi correlations in Auger electron spectroscopy
Authors: Rusch T.W. , Bertino J.P. , Ellis W.P.
Published: January 2004

Variations in Auger electron signal intensities with changing primary electron angle of incidence have been correlated with the Kikuchi display from a Si (111) surface. From this correlation a qualitative depth distribution of the carbon contaminant is inferred.
Temperature and frequency dependence of infrared absorption as a diagnostic tool
Authors: Sparks M.
Published: January 2004

Recent developments render untenable a proposed method of distinguishing between intrinsic and extrinsic infrared absorption on the basis of the proposed temperature dependence. However, when the proper temperature dependence of multiphonon absorption is accounted for and the possibility of other intrinsic processes is taken into account, the temperature and frequency dependence of the absorption of both the best available and intentionally imperfected crystals should be useful in studying extrinsic processes.
Analysis of intensity correlation spectra of mixtures of polystyrene latex spheres by least squares
Authors: Bargeron C. B.
Published: January 2004

This letter presents the results of an experimental investigation of the self-beat intensity correlation spectra of light scattered from mixtures of two sizes of polystyrene latex spheres of an approximately 1 : 2 diameter ratio. The precision of the data permits the deduction of scattering amplitude ratios (concentration ratios) and particle diameters by straightforward least-squares analysis, which, in general, are within 5% of actual values. The use of computer-evaluated uncertainties in calculating weighted means is found to improve the statistical analysis.
High-power ultraviolet laser radiation from molecular xenon
Authors: Hughes William M. , Shannon J. , Kolb A. , Ault E. , Bhaumik M.
Published: January 2004

Experiments have been conducted on high-pressure Xe gas undergoing excitation by a high-current pulsed relativistic electron beam. Spectral, temporal, and calorimetric diagnostics were performed. The results establish that lasing in molecular Xe has been achieved with the highest laser power yet obtained in the vacuum ultraviolet. Premature termination of light output indicates the possibility of significant effects due to thermal collisions.
High-frequency electron conductivity mobility in vapor-phase homoepitaxial silicon
Authors: Wen C.P. , Chiang Y.S. , Young A.F. , Presser A.
Published: January 2004

The average room-temperature electron conductivity mobility μc in silicon measured at ultrahigh frequencies was found to be approximately 30% higher than the average drift mobility reported in the literature for bulk samples with identical resistivity. The discrepancy is attributed to the minimized effect of traps in silicon at ultrahigh frequencies where the period of the rf signal is considerably shorter than the lifetime of the traps.
Bistable impedance states in MIS structures through controlled inversion
Authors: Kroger H. , Wegener H.A.R.
Published: January 2004

Metal silicon-nitride n-p+ silicon diodes have been fabricated with I-V characteristics similar to those of a four-layer diode. Switching between the two impedance states, whose impedance levels differ by a factor of the order of 106, can be accomplished in less than 5 nsec. The impedance of the device is controlled by the presence or absence of the inversion layer of the MIS structure. Both impedance states require a nonzero conductance of the insulator.
Properties of Nb Josephson microbridges
Authors: Laibowitz R.B.
Published: January 2004

Electron-beam lithographic techniques have been used to fabricate Nb microbridges, and their superconducting properties have been investigated. A reduced Tc is found for some of the links, and microwave-induced steps and the temperature dependence of the critical current consistent with the Josephson effect are observed.
Lorentz electron microscopy of magnetic domains in a Co–Ce permanent magnet
Authors: Leamy H. J. , Green M. L.
Published: January 2004

Lorentz electron microscopy techniques have been applied to a study of 180° magnetic domain wall structure in a Co3.5CuFe0.5Ce1.09 permanent magnet. The asymptotic wall width δ was determined to be 94 Å, accurate to within approximately ± 30%. This leads to a wall energy of ∼ 24 erg/cm2 and an exchange constant of ∼ 1.8 × 10−6 erg/cm when the standard continuum model for the wall structure is assumed.
Surface-wave acoustoelectric image scanner
Authors: Takada S. , Hayakawa H. , Mikoshiba N.
Published: January 2004

An optical image scanning method using the longitudinal acoustoelectric effect by surface waves in the coupled p-Si/LiNbO3 system is described. By means of the coupling between electrons in a weak inversion layer and surface waves (frequency, 87 MHz; time duration, 400 nsec), a resolution of 2 lines/mm can be obtained.
Acousto-optic diffraction of guided optical waves in LiNbO3
Authors: Schmidt R. V. , Kaminow I. P. , Carruthers J. R.
Published: January 2004

We report acousto-optic diffraction modulation of a guided optical wave in LiNbO3 by an acoustic surface wave. 250 mW of acoustic power produces 100% modulation of the zero-order beam.
Picosecond framing photography of a laser-produced plasma
Authors: Richardson M. C. , Sala K.
Published: January 2004

Sequential two-dimensional photographs of a laser-produced plasma in air with effective individual exposure times of [inverted lazy s] 5 psec have been obtained by utilizing a focal-plane optical Kerr effect shutter.
HF chemical lasing at higher vibrational levels
Authors: Mayer S. W. , Taylor D. , Kwok M. A.
Published: January 2004

HF lasing has been obtained from the P6(5) and P6(4) transitions as well as several P5 and P4 transitions of HF. Lasing from these high vibrational levels was produced by transverse pulsed discharges in mixtures of HI, He, and SF6 or SO2F2. The low bond energy of HI contributed to doubling the energy of laser pulses compared to the energy observed when H2 was substituted for HI. The HF laser frequencies were also measured for other fuels with low RH bond energies.
Optical storage in VO2 films
Authors: Smith A. W.
Published: January 2004

The use of VO2 films for direct-bit optical storage with near-infrared lasers is demonstrated. The VO2 response is fast (< 10 ns), and large read signals are obtained with unpolarized light. A writing threshold of 0.03 nJ/μm2 is observed.
Electro-optic properties of reverse-biased GaAs epitaxial thin films at 10.6 μm
Authors: Cheo P. K.
Published: January 2004

Measurements of the electro-optic properties of high-resistivity GaAs epitaxial thin films have been made at the 10.6-μm CO2 laser wavelength by a novel rf interferometric technique. The described technique affords very accurate and convenient measurements of the phase shift of a 10.6-μm guided wave mode in thin films as a function of reverse-biased junction voltage. The measured electro-optic coefficient for thin films is found to be in good agreement with conventional measurements, r41 = 1.2 × 10−10 cm/V at 10 μm, for bulk GaAs electro-optic crystals.
Jet stream cw dye laser for high-resolution spectroscopy
Authors: Grove R. E. , Wu F. Y. , Hackel L. A. , Youmans D. G. , Ezekiel S.
Published: January 2004

A stable single-frequency jet stream cw dye laser has been used to obtain an absorption spectrum of the hyperfine structure of I2127 in a molecular beam with a resolution of 5 parts in 109.
HgCdTe varactor photodiode detection of cw CO2 laser beats beyond 60 GHz
Authors: Spears D. L. , Freed Charles
Published: January 2004

The simultaneous operation of a HgCdTe photodiode as an optical heterodyne receiver and a varactor microwave harmonic generator and frequency downconverter has made possible the detection of CO2 laser beats to beyond 60 GHz.
Infrared photovoltaic detectors from ion-implanted CdxHg1−xTe
Authors: Marine J. , Motte C.
Published: January 2004

We have fabricated n-p photovoltaic detectors in CdxHg1−xTe using aluminum implantation to create the n-type region. Implanted diodes made in this material with a composition x = 0.18, which corresponds to a band gap of 0.1 eV, had a zero-bias resistance of 1 kΩ at 77°K for a 200 × 250-μm sensitive area. The spectral response was almost flat in the range 4–12 μm with a quantum efficiency as high as 57% at 10.6 μm. The measured detectivity for a 30° field of view is 7.3 × 1010 cm Hz1/2 W−1 at 10.6 μm. This is one of the highest detectivities ever reported at this wavelength. Finally, the frequency response of these diodes used in a heterodyne detection system operating with a CO2 laser was 1 GHz.
X-ray photoelectron emission measurements of the valence band density of states and core levels of CuAlS2
Authors: Luciano M. J. , Vesely C. J.
Published: January 2004

We report x-ray photoelectron emission measurements of the ternary chalcopyrite compound CuAlS2. The measurements include the core electron levels and the valence band density-of-states distribution. The structure of the valence band includes the s band located 8.5 eV below the valence band edge, the p band located 3.0 eV below, and the copper d band located 0.7 eV below. Our measurements also indicate a higher degree of hybridization between the d and p bands than was observed in AgGaS2.
Epitaxial silicon layers grown on ion-implanted silicon nitride layers
Authors: Dexter R. J. , Watelski S. B. , Picraux S. T.
Published: January 2004

Buried layers of silicon nitride approximately 4000 Å in width have been formed by ion implantation while retaining a relatively undamaged silicon surface region. Epitaxial silicon of 2-μm thickness grown on these surfaces exhibits significantly lower defect concentrations than do silicon layers on spinel, as determined by optical microscopy and by proton channeling measurements. The breakdown voltage of the silicon nitride layers is approximately 7 × 105 V/cm, and the refractive index is 2.05 at 6328 Å.
Reversible microstructural control of electrical properties of WSe2
Authors: Sproul William D. , Richman Marc H.
Published: January 2004

Microstructural occlusions in semiconductor single crystals of WSe2 affect the electrical properties of the material. The presence of the occlusions, which are believed to be a new phase of tungsten selenide, W3Se4, increases the size of the band gap by a factor of 2. Annealing at temperatures just below the decomposition temperature of WSe2 causes the occlusions to revert back to the normal WSe2 structure.
Zinc ion implantation of sulfur-doped GaP
Authors: Hemenger P. M. , Dobbs B. C.
Published: January 2004

Sulfur-doped GaP has been implanted with 250-keV Zn ions to a total dose of 1016 cm−2 and then annealed at 900 °C. Hall data obtained with the van der Pauw configuration indicate type conversion in a surface layer that has a thickness, estimated from diffusion data and electrical transport properties, on the order of 10 μm. For large implant doses followed by annealing, the diffusion of Zn in GaP plays a significant role in the final location of the implanted ions.
Fast linear detection system for TE CO2 lasers
Authors: Alcock A. J. , Walker A. C.
Published: January 2004

A preliminary study of up-conversion as an approach to high-speed detection of 10.6-μm laser radiation is reported. Using synchronized Nd : YAG and TEA CO2 lasers, conversion to 0.96-μm radiation in proustite has permitted the detection of mode-locked TEA laser pulses with an overall system bandwidth of 900 MHz.
Defect structure introduced during operation of heterojunction GaAs lasers
Authors: Petroff P. , Hartman R. L.
Published: January 2004

The nature and origin of the defects responsible for the rapid degradation of stripe geometry GaAs–GaAlAs double-heterostructure lasers have been identified by transmission electron microscopy. These defects are formed by a three-dimensional dislocation network which originates at a dislocation crossing the GaAlAs and GaAs epilayers. The propagation of the dislocation network takes place by a climb mechanism induced by the operation of the device.
Effect of neutron irradiation on GaAs1−xPx electroluminescent diodes
Authors: Epstein A. S. , Share S. , Polimadei R. A. , Herzog A. H.
Published: January 2004

Light-emitting diodes fabricated from the GaAs1−xPx alloy system undergo degradation upon neutron irradiation. It has been found that the smallest change in efficiency occurs when the composition of the alloy is between x = 0.30 and x = 0.75. The change in minority-carrier lifetime, however, is approximately constant throughout the entire alloy range. It is suggested that the relative insensitivity to neutron irradiation of the efficiency in the alloy range x = 0.30–0.75 is connected with the inherent disorder already present within the GaAs1−xPx alloy system.
Laser Doppler interferometry for measuring small absorption coefficients
Authors: Skolnik L. H. , Hordvik A. , Kahan A.
Published: January 2004

A laser Doppler interferometric technique for measuring small absorption coefficients of infrared-transmitting materials is described. The interferometer is calibrated as a remote temperature sensor by monitoring optical path length changes of the sample as a function of temperature. The sample is then irradiated by a CO2 laser and the change in optical path due to absorbed laser energy is observed interferometrically as a function of time. From this measurement and the calibration data, a temperature-vs-time curve is generated from which the absorption coefficient of the sample at 10.6 μ may be calculated.
Superconductivity in Nb–Ge films above 22 K
Authors: Gavaler J. R.
Published: January 2004

Niobium-germanium films which remain superconducting up to 22.3 K have been prepared by a high-pressure dc sputtering process. The high Tc's of these films are attributed to the formation of a more nearly perfect stoichiometric Nb3Ge compound than has previously been obtainable.
Bubble domains in magnetostatically coupled garnet films
Authors: Lin Y. S. , Grundy P. J. , Giess E. A.
Published: January 2004

Bubble domains have been observed in five composite garnet structures consisting of two epitaxial magnetic layers separated by a layer of nonmagnetic garnet. The static and ``ordering'' properties of the domains are described and the arrangement of the overlying domains is discussed as a function of bias field. It is shown qualitatively that the strength of the magnetostatic interaction between the two magnetic layers can be changed considerably by varying the relative film thicknesses in the composites.
Monte Carlo calculations of magnetic contrast from cubic materials in the scanning electron microscope
Authors: Newbury D. E. , Yakowitz H. , Myklebust R. L.
Published: January 2004

Monte Carlo calculations confirm that contrast observed in the scanning electron microscope from magnetic domains in materials of cubic anisotropy is due to the alteration of electron trajectories within the specimen. Results are presented for the effects of electron accelerating potential, specimen tilt, and rotation. The contrast arises mainly from the high-energy portion of the back-scattered electron distribution.
Formation of vanadium silicides by the interactions of V with bare and oxidized Si wafers
Authors: Tu K. N. , Ziegler J. F. , Kircher C. J.
Published: January 2004

Formation of vanadium silicides by the interactions of vanadium with bare and oxidized Si wafers has been studied by both x-ray diffraction and He ion backscattering techniques. X-ray diffraction was used to identify phases and ion backscattering to profile compositional changes. In the case of V on Si, the silicide VSi2, which is a silicon-rich phase, was found to form at temperatures from 600 to 1000 °C. In the case of V on SiO2, reactions took place only at temperatures above 800 °C, and the reaction products were identified to be V3Si, V5SI3, and V2O5. Both V3Si and V5Si3 are vandium-rich phases, and the V3Si that we found was a continuous layer between the substrate and the other two phases, and became superconducting at about 15 °K.
Electromigration failure in NiCr thin-film stripes
Authors: Satake Tomomitsu
Published: January 2004

Electromigration-induced failure in NiCr thin-film stripes is investigated. The composition of evaporated NiCr thin films is 77:23 Ni/Cr in weight %, according to a spectroscopic analysis. The mean time to failure (MTF) of NiCr thin-film stripes can be qualitatively expressed by a relation similar to that held in the MTF of Al thin-film stripes, i.e., MTF ∝ J−n exp(φ/kT). However, the values of n and φ of NiCr are 13 and 1.14 eV, respectively, whereas those of Al are 2 [inverted lazy s] 3 and 0.41 eV, respectively.
Modulation of hypersound by ultrasound via strong collinear interaction
Authors: Rouvaen J. M. , Bridoux E. , Moriamez M. , Torguet R.
Published: January 2004

We study theoretically and experimentally the collinear mixing of acoustic waves in lead molybdate. Owing to the large coupling constant of this crystal, we have obtained a very efficient acoustic mixer or modulator via the interaction of a 750-MHz hypersonic signal wave and a 140-MHz ultrasonic pump wave.
Comments on ``On the reflections of normal-incidence Bleustein-Gulyaev surface waves''
Authors: Chen Chin-Lin
Published: January 2004

An algebraic error is found in a recently published letter. Because of this error, coupled with an oversimplified assumption, an incorrect conclusion is obtained.
Surface wave harmonic generation on sapphire and α-quartz
Authors: Vella P.J. , Stegeman G.I.A.
Published: January 2004

The cross sections for second harmonic generation of surface acoustic waves have been calculated from the rigorous theory of thermoelasticity. In this treatment, the nonlinear wave equation is satisfied by mechanical displacements which also maintain the boundary stress free at the harmonic frequency. Calculations for various cuts on α-quartz and sapphire are presented.
An electron attachment plasma instability
Authors: Douglas-Hamilton D. H. , Mani Siva A.
Published: January 2004

A new type of plasma instability is described in an electron-beam ionized discharge. This instability occurs in gas mixtures in which the dissociative attachment rate increases strongly with electric field. It has been observed experimentally in He:H2O 740:20 and in He:CO2 1:1 and 9:1 mixtures. The values of the ionization source function S and of the electric field E at which the wave instability occurs are predicted using a Fourier analysis of the linearized kinetic rate equations. This yields the condition for instability as S < (1/α)[Eδβ/δE) − β]2, where α is the electron-ion recombination coefficient and β is the electron neutral attachment rate.
Electroluminescence and photoluminescence of GaAs : Ge prepared by liquid phase epitaxy
Authors: Kressel H. , Ettenberg M.
Published: January 2004

Optical data are presented relating the photoluminescence emission of GaAs : Ge epitaxial layers with hole concentrations in the range from 6 × 1016 to 2.7 × 1019 cm−3. These data are supplemented with electroluminescence results obtained using diodes where the p side of the junction consists of GaAs : Ge. Measurements reported include the peak position of the electroluminescence and photoluminescence peaks, half-intensity bandwidths, and radiative efficiency at room temperature.
Theory of far-infrared generation by optical mixing and stimulated Raman scattering via spin-flip transitions in InSb
Authors: Shen Y. R.
Published: January 2004

Far-infrared generation by optical mixing and by stimulated Raman scattering via spin-flip transitions is treated using the general formalism of coherent excitation of polaritons. Practical numerical examples for InSb are given. The result for the case of optical mixing agrees well with the experimental result of Nguyen and Bridges. The calculation also suggests that the far-infrared output from a spin-flip Raman laser should be easily observable.
Field-dependent conductivity of chalcogenide glasses
Authors: Reinhard D. K. , Arntz F. O. , Adler D.
Published: January 2004

The preswitching exponential increase of dark conductivity with field observed in many chalcogenide glasses can be identified with either a change in the free-carrier concentration or a change in the carrier mobility. Small-signal photoconductance measurements on thin films of amorphous Te40As35Si15Ge7P3 in the field-activated regime indicate that it is the carrier concentration which increases exponentially with applied field. In addition, studies of variations in switching parameters introduced by intense electron irradiation suggest that a critical degree of carrier trapping is not a precursor to threshold switching. Both the photoconductivity and the electron-irradiation results indicate a very short carrier lifetime in these films.
Waveguide TEA laser
Authors: Smith P. W. , Maloney P. J. , Wood O. R.
Published: January 2004

We describe a miniature transverse-excitation CO2 laser in which the 10.6-μm laser radiation is confined within a hollow rectangular-cross-section dielectric and metal waveguide. Using a flowing mixture of CO2, N2, and He we have obtained laser action at pressures up to 1 atm, and pulse repetition rates as high as 4 kHz.
Enhancement of photoelectron density in TEA lasers using additives
Authors: Seguin H.J.J. , Tulip J. , McKen D.
Published: January 2004

The photoplasma produced in laser gases by a spark uv source is measured using a microwave bridge. The results show that an increase in plasma density of four orders of magnitude is obtained using trace amounts of low-ionization-threshold additives in the gas mix. The technique has been shown to enhance laser performance. An output energy density of 60 J/liter has been obtained from such a photoionized TEA laser.