摘要:

A new type of flexoelectric realignment is predicted which has a threshold voltage and occurs for only one polarity. It requires the anchoring of the alignment to be of different strength on the two electrodes.

ISSN:0003-6951    

DOI:10.1063/1.1655006

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Two recent papers describing the effects of charge‐transfer acceptors on the electro‐optical properties of a nematic liquid crystal are discussed on the basis of electrochemical considerations. A new interpretation is suggested which is consistent with the experimental facts.

ISSN:0003-6951    

DOI:10.1063/1.1655007

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

In this letter, we report a novel temperature‐sensing device based on the optical rotatory power of cholesteric liquid‐crystal films. The transducer is small and compact, compatible with lasers and fiber optics, and capable of resolving temperature differences of 0.02 °C or better. It is simpler and more precise than most liquid‐crystal techniques and does not pose the hazard that may be posed by electrical temperature sensors in certain applications. Dilute solutions of cholesteric liquid crystals in nematic solvents exhibit highly temperature‐dependent optical rotation near the isotropic phase transition temperature. We place these solutions between crossed polarizers and measure the temperature by monitoring the transmission accurately. Using a laser source, we have installed a device of this nature at the end of a bundle of fibers with encouraging results.

ISSN:0003-6951    

DOI:10.1063/1.1655008

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The variation in the ferroelectric transition temperature with deuteration is described by a linear function only if the deuteration level in the crystal is considered. A least‐squares fit of these data resulted in the relationTc=121.7K+ 1.07m, withmin mole% D. The effective distribution coefficient (keff) of deuterium in the system KH2PO4&sngbnd;KD2PO4&sngbnd;D2O was found to vary from 0.75 to 0.99 over the range of 25–99.8 mole% D.

ISSN:0003-6951    

DOI:10.1063/1.1655009

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A large number of pyroelectric detectors, fabricated from commercially available PVF2and poled under a variety of conditions of voltage, temperature, and time have been evaluated for responsivity and uniformity of polarization in the direction of the poling field. Results show that uniformity of polarization (a requirement for flat frequency response) can be achieved and responsivities as high as 2.9 &mgr;A/W can be obtained.

ISSN:0003-6951    

DOI:10.1063/1.1655010

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Electron impact ionization rates for an impurity‐related electron trapping center in amorphous SiO2films have been determined. These rates were obtained from analyses of trap population kinetics during uv‐stimulated photocurrent injection. The dependence of the impact ionization rate &agr;Non accelerating electric fieldEhas been parameterized: &agr;N= 25 exp(−1.5/E) cm−1, forEin MV/cm. This expression is the statistical average of results from three MOS specimens with a mean volume‐averaged trapping state densityN≈5×1013cm−3.

ISSN:0003-6951    

DOI:10.1063/1.1655011

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Plexiglas and metal targets were illuminated in atmospheric air with aQ‐switched neodymium : glass laser. Augmentation of the laser‐induced stress waves was achieved with paint and water coatings. The spallation of Plexiglas and lead was observed. Measurements of the stress‐time histories were taken with quartz stress gauges affixed to the rear surface of aluminum targets.

ISSN:0003-6951    

DOI:10.1063/1.1655012

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Flat‐band shift measurements were made onp‐type MOS devices irradiated with electrons at various gate bias voltages. A reproducible curve of flat‐band shift versus gate bias was obtained that could not be readily accounted for with existing models. Data were taken over a wide range of negative and positive gate bias voltages. The model assumes that traps obey Fermi‐Dirac statistics, subject to interface boundary constraints. A linearized quasi‐Fermi level is assumed in the oxide. The resulting distribution of charged traps yields a self‐consistent energy band structure throughout the entire device.

ISSN:0003-6951    

DOI:10.1063/1.1655013

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Liquid phase epitaxy of GaAlAs was performed on GaAs fine surface corrugations. By optimizing the growth conditions, GaAlAs layers were grown successfully with only minimal meltback.

ISSN:0003-6951    

DOI:10.1063/1.1655014

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

We propose a pulse compression scheme which reduces the peak intensity while increasing the energy density achievable in a Nd:glass amplifier chain. Self‐focusing is the dominant effect responsible for limiting the power of a short‐pulse Nd:glass amplifier chain, and the reduction of the intensity (through this compression scheme) greatly reduces these problems. We recommend injecting a lower‐intensity and longer‐duration pulse into the chain. Under some circumstances, the glass nonlinearity will impress upon the pulse a chirp suitable for efficient subsequent temporal compression, and this may result in higher effective peak power operation. If a 1‐nsec (full 1/eduration) temporally Gaussian pulse with a chain‐averaged peak intensity of 2 GW/cm2propagates 2 m in a Nd:glass laser chain, we calculate that the pulse could be subsequently compressed (by a series of Gires‐Tournois interferometers) to 125 psec with good stability against input pulse amplitude noise. Such short pulses are of major interest for laser fusion.

ISSN:0003-6951    

DOI:10.1063/1.1655015

出版商:AIP    

年代:1974

数据来源: AIP