摘要:

By applying mechanical stresses to evaporated Ni films it is possible to shift the ferromagnetic resonance field to such a low value that even at zero field, transverse phonons at 9.4 GHz are generated by magnetostriction.

ISSN:0003-6951    

DOI:10.1063/1.1652524

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

Extrinsic far‐infrared photoconductivity has been observed at 4.2°K in high‐purityn‐type epitaxial layers of GaAs grown on Cr‐doped semi‐insulating GaAs substrates. Measurements of the responsivity and noise in the detection system at 300 Hz in a 1‐Hz bandwidth yield an NEP of 1.2 × 10−11W at 195 &mgr;, 1.4 × 10−12W at 337 &mgr; and 6 × 10−11W at 902 &mgr;. The time constant of the detector has been determined to be shorter than 1 &mgr;sec using a Ge avalanche modulator to chop the incident radiation. A time constant of about 5 nsec has been measured using impact impurity ionization in the GaAs.

ISSN:0003-6951    

DOI:10.1063/1.1652525

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

The sputtering efficiency (i.e. ratio between sputtered energy and impinging ion energy) has been measured for 30–75‐keV lead ions impinging on polycrystalline lead. The results are in good agreement with recent theoretical estimates.

ISSN:0003-6951    

DOI:10.1063/1.1652526

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

A resonator having a multiplicity of degenerate fundamental modes was formed of three mirrors in a split confocal arrangement with He&sngbnd;Ne as the laser active medium. It provided sufficiently low loss at 6328 Å to demonstrate mode selection by translation of an aperture near one end mirror. This configuration was adapted to sensitive measurement of mirror surface nonuniformity.

ISSN:0003-6951    

DOI:10.1063/1.1652527

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

Ions resulting from the impact of hypervelocity microscopic particles upon a solid Ta target have been analyzed by time‐of‐flight techniques. The impact velocity of the micron‐size and smaller, predominately iron particles (∼98% Fe) ranged from 2 to 45 km/sec, which corresponds to an energy range of from 1 to 600 eV/atom. The kinetic energy of the particles is converted into internal energy of an expanding, partially ionized vapor cloud composed of both target and particle material. The energy conversion process occurs on a time scale comparable to that involved inQ‐switched laser beam‐solid target interactions. In addition to ions of both the bulk target and particle materials, a number of other ion groups are observed which are presumed to be impurities from both the particle and target. A tentative model describing the process is discussed.

ISSN:0003-6951    

DOI:10.1063/1.1652528

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

A new electro‐optic effect is presented, based on guest‐host interactions in nematic liquid crystals. The ability of a nematic liquid crystal to cooperatively align in an electric field is used to orient ``guest'' dichroic dye molecules (molecules whose absorption spectrum is a function of the molecular orientation with respect to the polarization of the incident light). Thus one can electrically switch the color of transmitted light using fields of the order of 104V/cm.

ISSN:0003-6951    

DOI:10.1063/1.1652529

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

This Letter reports the generation of shear waves at microwave frequencies by magnetically biased epitaxial films of yttrium iron garnet deposited on yttrium aluminum garnet. These acoustic transducers are electronically tunable and permit single echos to be electronically selected from delayed pulse trains.

ISSN:0003-6951    

DOI:10.1063/1.1652530

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

Experiments are described in which a plasma is used as an impedance element in an active Fabry‐Perot microwave resonator which contains a positive feedback loop. The arrangement functions as aQmultiplier or as an oscillator, with the plasma acting as a power or frequency‐determining element. The characteristics of the active Fabry‐Perot resonator are discussed in connection with diagnostic methods for pulsed and steady‐state plasmas.

ISSN:0003-6951    

DOI:10.1063/1.1652531

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

A new type of mode selector is described which uses a short confocal cavity illuminated off‐axis. The mode selector is generally similar to a Fox‐Smith interferometer, but is easier to use, because it does not need to be mode‐matched to the laser. Experimental results obtained using the confocal interferometer with an argon‐ion laser are described.

ISSN:0003-6951    

DOI:10.1063/1.1652532

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

A simple experimental procedure based on measurements of the acoustoelectric after‐current is described for estimating the frequency of maximum intensity of the amplified acoustic flux at various stages of its buildup. In CdS, the rapid buildup in flux leading to current saturation is followed by a slower growth which continues until the flux domain leaves the filament. The frequency of maximum intensity coincides initially with the frequency of maximum gain and decreases continuously as the domain propagates down the filament, reaching in a typical case a value ten times smaller.

ISSN:0003-6951    

DOI:10.1063/1.1652516

出版商:AIP    

年代:1968

数据来源: AIP