摘要:

Epitaxial structures grown by alternate monolayer depositions of GaAs and AlAs are reported. As many as 104alternate (100) layers of GaAs and AlAs as thin as 1.0±0.1 and 1.0±0.1 monolayers, respectively, were deposited by sequential molecular beam epitaxial growth on a (100)GaAs substrate. Transmission electron microscopy showed the resultant films to be perfectly epitaxial with layered composition modulation of the expected periodicity. Their electronic properties were studied by optical absorption and luminescence.

ISSN:0003-6951    

DOI:10.1063/1.89082

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A simple real‐time light valve based on selenium and the cholesteric‐nematic phase transition is described. The device is optically addressed and can be read out in real time with very intense white light sources without need for an optical blocking layer. Operation involves the absorption characteristics of the photoconductor and space‐charge‐limited currents. The principle can be extended to other combinations of photoconductors and electro‐optic effects.

ISSN:0003-6951    

DOI:10.1063/1.89083

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The relaxation spectra of a cold‐rolled Pd‐Cu‐Si glass are very similar to that of the initially quenched glass, except for the low‐temperature peak at 400 °K. About 4% of expended energy is stored in the glass. A possible mechanism is that the stored energy arises from local heating and quenching in shear bands. The bandwidth and the stored energy in the shear bands are of the order of 2500 A˚ and 2.5×104erg/cm2, respectively.

ISSN:0003-6951    

DOI:10.1063/1.89084

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Continuously cast metallic glasses [METGLASR(trademark of the Allied Chemical Corporation) alloys] based on the transition metals (TM) iron, cobalt, and nickel can now be synthesized containing boron as the only metalloid. The different electron‐donor effects of boron and phosphorus are clearly seen for the first time; each atom of these metalloids gives ∼1.6 and 2.4 electrons, respectively, to the TMdbands. Extrapolation of the available magnetic moment data suggests a nonzero moment on nickel in (TM)80B20glasses. The boron‐containing metallic glasses generally show higher Curie temperatures and room‐temperature saturation magnetizations than mixed‐metalloid glassy alloys of the same TM content.

ISSN:0003-6951    

DOI:10.1063/1.89085

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A strain‐controlling film to change acoustic strain distributions in the interaction region between acoustic surface waves and optical guided waves is introduced to improve the Bragg‐diffraction efficiency in surface‐acoustic‐optic devices. An improvement of about 2 orders of magnitude has been achieved in the efficiency of TM0‐TM0diffraction at an acoustic frequency of 130 MHz in a 2.0‐&mgr;m ZnO‐film optical waveguide with a strain‐controlling film of a 1.5‐&mgr;m‐thick fused‐quartz film, as predicted by the theory.

ISSN:0003-6951    

DOI:10.1063/1.89086

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The behavior of a large‐area field emission diode located in a 4:1 converging magnetic gradient is described. Evidence is presented that this technique significantly reduces the early‐timeL/Rdecay into the nominal 3/4 &OHgr; space‐charge‐limited impedance characteristic. The elimination of late‐time plasma closure in the diode gap is also demonstrated. Due to these characteristics, a significant reduction in the time‐averaged diode impedance and an improvement in the pulse‐line–diode energy transfer efficiency has been obtained—thereby permitting first observations of efficient matching to a sub‐ohm pulsed electron accelerator.

ISSN:0003-6951    

DOI:10.1063/1.89087

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A TiO2–solar‐cell hybrid structure has been used successfully as the anode electrode in the photoelectrolysis of water. The TiO2films have been fabricated by chemical vapor deposition. Conversion efficiency of solar energy of about 0.1% has been attained in the preliminary experiment.

ISSN:0003-6951    

DOI:10.1063/1.89088

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A solution growth technique has been developed to obtain polymer films doped with high concentrations (up to 18% by weight of polymer) of metals such as Cu, Co, Ni, and Fe. Electron microscopy, EPR, and optical studies of Cu‐doped polyvinylchloride films show the existence of homogeneously distributed copper in colloidal, Cu+, and Cu2+states.

ISSN:0003-6951    

DOI:10.1063/1.89071

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

YAG:Nd polycrystals have been prepared in which the fluorescent lifetime of the4F3/2state is ∼420 &mgr;sec, in excellent agreement with the previously measured cross section and branching ratios. When such polycrystals are either fused or used to pull single crystals from melt, the fluorescent lifetime is reduced to ∼280 &mgr;sec. This is attributed to the creation of defects at high temperatures which can act as quenching centers. Various mechanisms for nonradiative decay of4F3/2are also discussed.

ISSN:0003-6951    

DOI:10.1063/1.89072

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Longitudinal mode beat intensities in a free‐running cw HF chemical laser have been investigated. A simple expression was derived that describes the variation of beat intensity with tuning frequency. Experimental observations of the variation of beat intensity with tuning frequency in a HF chemical laser agree with the theoretical prediction.

ISSN:0003-6951    

DOI:10.1063/1.89073

出版商:AIP    

年代:1976

数据来源: AIP