摘要:

A sensitive temperature dependence of the optical rotatory power of a cholesteric liquid‐crystal film in the vicinity of the smectic‐A phase is reported. The results are consistent with the pretransitional unwinding of the helical structure. The use of the effect in thermometry is discussed.

ISSN:0003-6951    

DOI:10.1063/1.89751

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

We demonstrate analytically and experimentally that the acoustic surface wavep‐ndiode storage correlator may be charged either very quickly or very slowly, depending on the input signal levels, and independent of the diode storage time. Thus, the same long storage time device is usable for both high‐speed and slow (such as integrating) applications.

ISSN:0003-6951    

DOI:10.1063/1.89752

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The visible interaction of low‐intensity ultrasonic waves with a nematic liquid crystal may be explained simply by the hypothesis of a torque tending to orient LC molecules perpendicular to the vibrations. It is shown how this torque can be related to anisotropic attenuation of ultrasound and minimization of propagation losses. First theoretical developments and optical measurements on a homotropic layer of MBBA are in good agreement and may predict a few simple general laws.

ISSN:0003-6951    

DOI:10.1063/1.89753

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The spectrum of the x‐ray continuum and line emission emanating from Al, Mg, and (CH2)nplasmas created with a nanosecond CO2laser pulse has been investigated at irradiance levels up to 2×1014W/cm2.

ISSN:0003-6951    

DOI:10.1063/1.89754

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The influence of uniaxial stress on the extrinsic photoconductivity of gallium‐doped germanium has been investigated. It has been found that the long‐wavelength cutoff is shifted from 114 &mgr;m for zero stress to 200 &mgr;m for a uniaxial stress of 6.6×103kg/cm2along a [100] direction. At this value of stress the responsivity was ∼2×104V/W and the NEP was ∼2×10−11W/Hz1/2at 190 &mgr;m.

ISSN:0003-6951    

DOI:10.1063/1.89755

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A vuv and soft x‐ray light source based on spontaneous anti‐Stokes scattering from atomic population stored in a metastable level is proposed. It is shown that the source has a maximum brightness equal to that of a blackbody at a Boltzman temperature characteristic of the population of the metastable level. This maximum brightness is attained as the media approaches two‐photon opacity. The source should have high resolution, may be of picosecond time scale, and on a pulsed basis should be brighter than other laboratory‐scale vuv light sources.

ISSN:0003-6951    

DOI:10.1063/1.89756

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A new type of discharge instability is reported for a low‐pressure Na–noble‐gas discharge (∼5×10−3Torr Na; 5.5 Torr Ne‐Ar, 1% Ar). The voltage‐current (V‐I) characteristic is shown to be multivalued in the voltage. The resulting instability is a discontinuity in the positive column which propagates in the direction of electron particle flow with velocity between about 105and 5×105cm/s.

ISSN:0003-6951    

DOI:10.1063/1.89757

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A few micron wide and thick polymer lines are formed from a monomer, methacrylic anhydride, according to a metal pattern of a mask under high‐energy radiation, such as &ggr; rays. The resolution is limited only by the mask configuration; with our present mask configuration it is better than ∼2000 A˚. The polymerization is initiated by electrons ejected from metal lines.

ISSN:0003-6951    

DOI:10.1063/1.89758

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The concentration profiles of phosphorus and knock‐on nitrogen in silicon after phosphorous implantations into Si3N4‐Si systems have been investigated by using secondary ion mass spectrometry (SIMS). The tails were found on the phosphorus distribution in silicon after the implantation through Si3N4films. The concentration profiles of knock‐on nitrogen in silicon have been determined by measuring both the in‐depth profiles of knock‐on nitrogen and those of nitrogen after additional nitrogen implantation into a bare silicon embedded with knock‐on nitrogen. The concentration profiles of knock‐on nitrogen show a very high concentration near the surface and extending tails. It was found that the tails were observed at the deeper portion in silicon as energy increased, for a given Si3N4layer.

ISSN:0003-6951    

DOI:10.1063/1.89747

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The luminescence of CuCl excited by a mode‐locked Nd3+ : YAG laser is studied at liquid‐helium temperature. It is recorded through an optical Kerr cell, used as a sampling gate, by an optical multichannel analyzer synchronized to the mode‐locked laser. At the excitation intensity used, athe luminescence of CuCl is essentially due to the radiative decay of biexcitons. The decay of this luminescence contains two components, a fast one (&tgr;≃95 ps) followed by a slower one (&tgr;≃450 ps).

ISSN:0003-6951    

DOI:10.1063/1.89748

出版商:AIP    

年代:1977

数据来源: AIP