摘要:

Dicarboxylatochromium complexes have produced very stable parallel molecular alignment of nematic liquid crystals, in contrast with a recently described perpendicular orientation by monocarboxylatochromium complexes. The complexes used are &mgr;‐dicarboxylato‐bis (tetranitro‐&mgr;‐hydroxodichromium (III))’s which bond chemically to substrate surfaces.

ISSN:0003-6951    

DOI:10.1063/1.88968

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

In this paper we report some observations of ultrasonic generation and detection at frequencies up to 9360 MHz using a piezoelectric electret transducer. The transducers were made with biaxially stretched polyvinylidene fluoride films.

ISSN:0003-6951    

DOI:10.1063/1.88969

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Piezoelectric effects are observed in a mixed cholesteric liquid crystal layer. It is sandwiched by a pair of nesa‐coated glass plates one of which is subjected to lateral motion to develop the shear vibration in the layer. It is found that the electric potential is generated from the layer, the frequency of which is the same as that of the exciting vibration. Three cases of the molecular orientation process for the liquid crystal layer are tested: (i) previous impression of dc voltage, (ii) lecithin application on the surfaces of the substrate glass plates, and (iii) previous static shear strain on the layer. 10–20 mV peak‐to‐peak (p‐p) are generated for the vibratory displacement of 1 &mgr;m (p‐p) of 25 kHz.

ISSN:0003-6951    

DOI:10.1063/1.88970

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

We describe a new method for making meander‐line surface acoustic wave electromagnetic transducers at megahertz frequencies from multiconductor flat cable. Commerically available cable, consisting of uniform patterns of rectangular conductors, is used to fabricate identical transducers with well‐characterized electrical and acoustical properties. Also new expressions for the electrical inductance and transduction efficiency of these transducers are presented and compared to measurement for several Rayleigh wave devices. Measured transducer bandwidths agree with a predicted (sinX/X)2response. Unique features of cable transducers are exploited in novel designs and applications such as precise velocity measurement and crack detection on curved surfaces.

ISSN:0003-6951    

DOI:10.1063/1.88971

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A strong magnetic‐field‐dependent room‐temperature attenuation of 618‐MHz surface waves propagating on aY‐cut quartz substrate coated with a 200‐A˚ nickel film was observed. The attenuation could be varied over a range of more than 25 dB/cm by external magnetic‐field changes of less than 10 Oe.

ISSN:0003-6951    

DOI:10.1063/1.88972

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

An optical image can be stored in the slow surface states of Ge and can be read out by the separated medium acoustoelectric effect with a surface wave on LiNbO3. It is found that the surface is sensitive to an optical pattern with optical power less than 1 &mgr;W/mm2at 368 nm wavelength. The memory time is considerably long due to the ’slow’ property of the surface states on Ge.

ISSN:0003-6951    

DOI:10.1063/1.88973

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A new principle of acoustic scanning of an optical image is described. The illumination modulates the storage time constant of a charge grating acoustically stored in ap−ndiode matrix. One surface acoustic pulse directly reads out the resulting charge distribution. Owing to integration effects, the device exhibits a very high sensitivity and an electronically variable contrast.

ISSN:0003-6951    

DOI:10.1063/1.88974

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The observation of the synchronous drag of minority carriers by the electric field associated with an acoustic surface wave is reported. This phenomenon is exploited in a new charge‐coupled device (CCD) which uses a traveling piezoelectric surface acoustic wave in place of the gate structure of a conventional CCD. The surface wave interaction CCD (SWICC) should have several potential advantages over normal CCD’s, including increased information density, higher speed, and lower power consumption.

ISSN:0003-6951    

DOI:10.1063/1.88975

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

An analysis of the diffraction efficiency of photorefractive holograms in ferroelectric crystals is shown to provide a novel technique for determining the nature and magnitude of the equivalent electron drift field. For a Fe‐doped lithium niobate crystal (0.05% per mole) we find that the total field consists of an intensity‐independent internal field of 8.5 kV/cm and a photogenerated field given by the conversion factor 1.4 ×106V cm/W.

ISSN:0003-6951    

DOI:10.1063/1.88976

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

We report here reflection‐ and transmission‐mode photoemission out to 1.4 &mgr;m from a biased field‐assistedp‐InGaAsP grown onp‐InP photocathode. The quantum yield in transmission is ∼0.1% from 0.9 to 1.4 &mgr;m. Dark current due to impact ionization by injected holes in the depletion region is observed.

ISSN:0003-6951    

DOI:10.1063/1.88977

出版商:AIP    

年代:1976

数据来源: AIP