摘要:

The advantages of using a simple analytic representation for experimental data requiring Abel inversion are explored. A simple yet versatile function is proposed, and its Abel inverse derived. Its use allows not only a fast and accurate inversion of the data but also a simple, straightforward calculation of the magnitude of the error in the inverted values in terms of the mean standard deviations of the parameters defining the proposed function. A full discussion of the sources of error and their relative importance is also presented, as well as a numerical example using simulated data. The analysis indicates that unless the measured data is error free to an extremely high degree, no amplification of the experimental error, inherent in the data, occurs with this inversion method even if only three or four adjustable parameters are employed in defining the analytic function.

ISSN:0003-6951    

DOI:10.1063/1.93892

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Spatially and temporally resolved plasma ion temperatures can be determined by measuring the Doppler‐broadened line profiles of transitions excited by charge‐exchange recombination reactions between fast hydrogen atoms and fully ionized low‐Zions. Plasma rotation velocity profiles can also be obtained. A sample result from the PDX tokamak using He+radiation is presented, and expected line intensities for model cases for PDX and TFTR are calculated.

ISSN:0003-6951    

DOI:10.1063/1.93893

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Noncrystalline metallic hydrides can be formed from certain crystalline Zr3Rh intermetallic phases by hydrogenation. X‐ray diffraction patterns, density measurements, and superconducting properties confirmed the transition from the crystalline to the amorphous phase by this solid state reaction. The transition can be explained in terms of a ‘‘chemical frustration’’ effect.

ISSN:0003-6951    

DOI:10.1063/1.93901

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The effect of argon ion bombardment on a silicon oxide film prepared on a Si(111) surface by dry oxidation was investigated by measuring partial yield spectra in addition to the oxygen induced Si 2pcore level shift. The experimental observations can be understood such that the SiO2network is decomposed at the initial stage of argon ion bombardment. In the following stage of bombardment, the silicon oxide films are sputter etched resulting in a decrease in the oxide film thickness.

ISSN:0003-6951    

DOI:10.1063/1.93902

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Results of initial attempts to grow cubic‐phase CdTe films on sapphire by molecular beam epitaxy are reported. Depositions have been completed on (11¯02)R‐plane, (12¯10)A‐plane, and (0001) basal plane substrates. Substrate temperatures in the range 260–350 °C were employed along with deposition rates of 1.5–7.5 A˚/s. Depositions on (11¯02) sapphire generally produced films containing some elements of the hexagonal phase, as disclosed by x‐ray diffraction and UV reflectance measurements. Sharp cubic‐phase epitaxy was obtained for thick (∼5 &mgr;m) CdTe films grown on (12¯10) and (0001) sapphire substrates. The epitaxial films are smooth and mirrorlike in appearance. Nomarski micrographs show a featureless CdTe surface.

ISSN:0003-6951    

DOI:10.1063/1.93903

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Undoped andinsituphosphorus‐doped low pressure chemical vapor deposited polysilicon films have been studied by various structural analysis and optical techniques as a function of deposition temperature. Polysilicon films of high quality can only be obtained by deposition in the amorphous phase and subsequent crystallization.

ISSN:0003-6951    

DOI:10.1063/1.93904

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

An analysis has been made of the tensile strength statistics of two silica fibers with quite different degrees of diameter uniformity. It has been found that the coefficient of variation in diameter (&ngr;d) is equal to that in minimum diameter (&ngr;d,min) and that the measured coefficient of variation in breaking load (&ngr;L) and breaking stress (calculated assuming constantd) are twice this value. Since &ngr;L=&ngr;&sgr;=2&ngr;d=2&ngr;d,minit is clear theapparentvariability in strength is the result of the variability in diameter and therefore therealstrength is essentially single valued. Because of this lack of statistical variation in breaking strength, it is suggested that these fibers are flaw‐free as drawn.

ISSN:0003-6951    

DOI:10.1063/1.93905

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

We report the first successful realization of room‐temperature laser action at a wavelength of 1.55 &mgr;m in a new double heterostructure in which the active layer of GaxAlyIn1−x−yAs is confined between two cladding layers of AluIn1−uAs. The structure was grown on InP by molecular beam epitaxy, and was pumped optically by aQ‐switched yttrium aluminum garnet laser. Peak output power of up to 5 W was obtained at an incident power corresponding to four times that required for threshold without catastrophic degradation. Temperature dependence of the threshold power can be characterized byPth∼exp(T/T0) withT0=60 °C for 20 °C≤T≤100 °C.

ISSN:0003-6951    

DOI:10.1063/1.93906

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Photoluminescence data are presented on a direct‐well GaAs1−xPx‐GaAs (x∼0.25) strained superlattice (SL) (barrierLB∼75 A˚, quantum wellLz∼75 A˚) and on indirect‐well GaP‐GaAs1−xPx(x∼0.6) strained SL’s (LB,Lz∼120 A˚ andLB,Lz∼60 A˚) grown by organometallic vapor phase epitaxy. Stimulated emission (at 300 and at 77 K) is observed in the former but only weak luminescence in the latter, thus establishing that a large density of defects at the heterointerfaces is not necessarily an issue in strained SL’s and that so far zone‐folding effects, and SL ‘‘indirect‐direct’’ conversion, have not been observed in indirect systems.

ISSN:0003-6951    

DOI:10.1063/1.93888

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

We have measured the time‐resolved decay of photoexcited carriers in InGaAsP subsequent to mode‐locked laser pulse excitation at 1.06 &mgr;. Carrier decay rates were evaluated from bleaching recovery and luminescence decay measurements as a function of injected carrier density over a two‐decade range (1017–1019cm−3). At low and moderate density the decay rate follows the variation with excitation expected for radiative decay. At high carrier density (above 2×1018cm−3), the decay rate increases more rapidly with carrier density, indicating the onset of nonradiative recombination which can be accounted for by Auger recombination with an Auger coefficient ofA=2.3±1×10−29cm6 s−1. This compares to the calculated Auger coefficient range of 0.7–1.4×10−28cm6 s−1. We discuss the influence of our measured decay rates on the threshold temperature dependence of InGaAsP‐1.3 &mgr; lasers by calculating expectedT0values, using a range of representative values for threshold carrier density and temperature dependence of the Auger decay rate. Our results suggest that while Auger recombination does contribute to the temperture dependence of the InGaAsP‐1.3 &mgr; laser it may not alone fully account for the observed room‐ temperatureT0values.

ISSN:0003-6951    

DOI:10.1063/1.93907

出版商:AIP    

年代:1983

数据来源: AIP