摘要:

The frequency and temperature dependence of the ultrasonic attenuation in glassy Pd&sngbnd;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/&mgr;sec 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 Pd0.775Ag0.06Si0.165shows 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.

ISSN:0003-6951    

DOI:10.1063/1.1654917

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

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.

ISSN:0003-6951    

DOI:10.1063/1.1654918

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

It was found that a layer of the nematic liquid crystalp‐N‐(p‐Methoxybenzylidene) aminon‐butylbenzen, extended on a triglycine sulfate crystal, takes on an orientational pattern which delineates the polarized domain structures. This technique quickly delineates domain structures in great detail and can be used on a wide variety of ferroelectric crystals. It is even applicable to a uniaxial regular type in which a domain structure cannot be detected by ordinary optical methods. The new method and the ordinary carbon powder pattern technique were compared on a triglycine sulfate crystal.

ISSN:0003-6951    

DOI:10.1063/1.1654919

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The effect of cyclotron resonance absorption upon laser‐induced gas breakdown is calculated. It is shown that the threshold power for breakdown is dramatically reduced at resonance. The calculations are carried out in the limits of both short and long laser pulses. In the short‐pulse limit, the threshold power is determined by the length of laser pulse; in the long‐pulse limit, it is determined by electron diffusion from the breakdown region and by energy loss resulting from elastic collisions.

ISSN:0003-6951    

DOI:10.1063/1.1654920

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The energy barriers forp‐nGe&sngbnd;AlxGa1−xAs and GaAs&sngbnd;AlxGa1−xAs heterojunctions have been determined by capacitance measurements. The results indicate that the valence band of AlxGa1−xAs tends to remain fixed with respect to the vacuum level for different values ofx. This leads to spiked barriers in the conduction band for these junctions. The values determined for the barriers are consistent with measurements onp‐pGe&sngbnd;GaAs junctions.

ISSN:0003-6951    

DOI:10.1063/1.1654921

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

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, thetemperature and frequencydependence of the absorption of both the best available and intentionally imperfected crystals should be useful in studying extrinsic processes.

ISSN:0003-6951    

DOI:10.1063/1.1654922

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Single nanosecond laser pulses at wavelengths near 10 &mgr;m have been obtained by using a pulsed HBr laser to optically pump pure CO2gas at pressures up to 33 atm in a 1‐mm‐long optical resonator. At pressures above 17 atm, the laser oscillates on the 10.3‐&mgr;mRbranch rather than on the usual 10.6‐&mgr;mPbranch.

ISSN:0003-6951    

DOI:10.1063/1.1654923

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Gain measurements have been made at wavelength intervals over the continuum bands of high‐pressure mercury excited by a short high‐intensity electron beam pulse. These measurements, which utilized both continuum and laser light sources, showed net absorption at all wavelengths tested. This indicates thatHg2*has a larger cross section for absorption than for stimulated emission to the repulsive ground state, and virtually elminates the chances of laser action on these transitions.

ISSN:0003-6951    

DOI:10.1063/1.1654924

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The vibrational and rotational temperatures in the supersonic flow of a gas‐dynamic laser have been determined simultaneously by using spectral gain measurement techniques (over a number of rotational lines). The vibrational and rotational temperature and, consequently, the optical energy in the flow are reported for two different gas‐dynamic lasers having significantly different area ratio nozzles and varying stagnation temperatures.

ISSN:0003-6951    

DOI:10.1063/1.1654925

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

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.

ISSN:0003-6951    

DOI:10.1063/1.1654926

出版商:AIP    

年代:1973

数据来源: AIP