摘要:

The effect of modulation amplitude on magnetic resonance linewidths &dgr;H(between slope extrema) and derivative signal intensity is examined. Experimental results are compared with theory for Lorentzian and Gaussian lines. Modulation amplitudes,hm, of 0.15&dgr;H[or 2hm(peak to peak) = 0.30&dgr;H] produce about 2% error in linewidths for Lorentzian signals and less than 1% error for Gaussian signals. Effects of modulation on linewidth and signal amplitude are presented in graphic and tabular form.

ISSN:0021-8979    

DOI:10.1063/1.1713596

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

The elastic constants of pure single crystals of CsBr and CsI have been measured at liquid‐helium, liquid‐nitrogen, and room temperatures. For CsBr, the values ofc11,c12, andc44at 4.2°K are 3.437, 1.035, and 0.999 in units of 1010N/m2. The corresponding values of CsI at 4.2°K are 2.737, 0.793, and 0.825·1010N/m2.The elastic constants give the Debye temperature 148.8°K for CsBr and 125.6°K for CsI.The infrared resonance frequencies calculated from compressibility data are in agreement with those obtained from infrared spectroscopy.

ISSN:0021-8979    

DOI:10.1063/1.1713597

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

The time of maximum switching currenttmof triglycine sulfate (TGS) crystals has been measured as a function of fieldEand crystal thicknessdin the ranges 102<E<103V/cm and 0.02<d<0.98 cm. The results may be expressed astm=t∞exp[&agr;0d−⅔/E] witht∞≃(1.3±0.3)×10−4sec and &agr;0=(4±1)×102V/cm. The symmetry of the switching transients abouttmis a function ofdand increases slightly withE.The symmetry factormvaries fromm=0.7 tom=0.4 for 0.5<d<1.0 cm in agreement with a model for polarization reversal in which the virtual sidewise displacement of domain walls is the dominant mechanism. For thin crystals,d<0.15 cm andm<0.1, a model based on dominant nucleation and growth of antiparallel domains is consistent with experimental observations.

ISSN:0021-8979    

DOI:10.1063/1.1713598

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

Hall effect results on GaAs crystals into which Li is introduced at 500°C, as well as at higher temperatures, and subsequently removed in Ga or in air at 500°C are reported. Four acceptor ionization energies: 0.023 and 0.11 eV (previously reported), 0.05 eV and 0.14 eV are found. The two levels 0.023 and 0.05 eV are attributed to Li self‐pairs. The 0.11‐ and 0.14‐eV levels are associated with Cu possibly already present in the GaAs crystals. The 0.023‐eV level is found in crystals produced by the floating‐zone process at all temperatures of the Li diffusion. The 0.023‐eV level is also found in the horizontal Bridgman crystals when diffusion is above ∼650°C. Below ∼500°C, however, the 0.05‐eV level predominates in Bridgman crystals and the 0.023‐eV level is not observed. The origins of the various levels are discussed.

ISSN:0021-8979    

DOI:10.1063/1.1713599

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

A study has been made of the mutual solid solubility of the phosphides, arsenides, and antimonides of gallium and indium, all of which crystallize in the zinc‐blende structure. The films were prepared by flash evaporation of mixed powders. X‐ray diffraction analysis of the films showed that all of the phosphides and arsenides form a complete range of solid solutions, while the phosphides and antimonides are largely immiscible. In the arsenide‐antimonide systems, only those containing a common group III element are completely miscible (e.g., InAs&sngbnd;InSb, GaAs&sngbnd;GaSb). All quasibinary systems with a common group V element form a complete range of solid solutions. The results have been extrapolated to give a schematic representation of the limits of solubility in the multicomponent system In&sngbnd;Ga&sngbnd;P&sngbnd;As&sngbnd;Sb. The solubility has been correlated with the size of the component atoms involved in each system. Where solid solution occurred, the lattice constants were found to obey Vegard's law within the limits of accuracy. Epitaxy was achieved by depositing the films onto single‐crystal germanium. Optical absorption has been measured on films covering a wide range of compositions.

ISSN:0021-8979    

DOI:10.1063/1.1713600

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

The refractive index of GaAs, as measured by the prism refraction method, is reported here for photon energies from 0.7 eV up to the absorption limit set by the band gap, for temperatures of 300°, 187°, and 103°K. The results are compared with the previous data (obtained only for room temperature), and are used to show that the spacing of emission lines of GaAs lasers corresponds to that of the axial modes of a Fabry‐Perot resonator.

ISSN:0021-8979    

DOI:10.1063/1.1713601

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

The phenomenon of free carrier absorption in germanium has been utilized to modulate infrared radiation. Criteria are established which provide bases for judging and comparing modulator performance. By solving the small‐signal continuity equation for the spatial and temporal distribution of excess holes, expressions are obtained which relate the modulator performance to the fundamental electro‐optical properties of the modulator material. Modulators have been fabricated having modulation bandwidths in the range 105to 106cps. Experimentally determined modulator characteristics are compared with theoretical predictions.

ISSN:0021-8979    

DOI:10.1063/1.1713602

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

Hardening by gamma irradiation was investigated in eleven alkali halides with the rocksalt structure. The linear dependence of the flow stress upon the one‐half power of theF‐center concentration, as previously observed in LiF and KCl, was also observed in these new substances. (The earlier experiments showed that the hardening is not actually caused byFcneters but by a defect resulting fromF‐center production.) The rate of hardening with concentration was found in all cases to be consistent with that to be expected for non‐symmetrical defects. Comparisons were also made between the amount of hardening per defect and the lattice spaces available to certain specific defects. The only clear correlation was with a halogen atom in the interstitial space at coordinates 0, ¼, ¼ in the unit cell.

ISSN:0021-8979    

DOI:10.1063/1.1713603

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

Fast He atoms are shot into one side of the tungsten emitter tip of a field ion microscope, and the resulting damage to the surface, consisting of vacancies, interstitials, and their clusters, is observed in atomic resolution. About one‐half of the number of atoms calculated to have received a displacement energy of 50 eV in the interior appear as surface defects. The surface integrates the damage by focusing collisions coming from as deep as 1000 Å. Stress enhanced mobility of subsurface interstitials is detectable at 21°K, and rapid thermal diffusion from the depth occurs at 90°K.

ISSN:0021-8979    

DOI:10.1063/1.1713604

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

Selected area x‐ray diffraction was employed to study the localized structural changes resulting from sliding of a hemispherical copper stylus on the (001) face of a copper single crystal. Although a relatively large (0.25 mm) x‐ray beam was used, significant structural deformations were resolved. Features observed included deformation of boundary regions by rotation from slip, crystal bending in areas of pileup, the micro‐crystalline Beilby layer, a preferentially oriented transition region, and transferred crystalline particles. The observed deformations exhibited a dependence on sliding direction.

ISSN:0021-8979    

DOI:10.1063/1.1713605

出版商:AIP    

年代:1964

数据来源: AIP