摘要:

The addition of charge‐transfer acceptors to a nematic liquid crystal at concentrations <0.1% has a profound effect on the voltage‐transmission characteristics for dynamic scattering, reducing the threshold voltage by a factor of 2 for dc fields, but not appreciably altering the ac behavior. Charge‐transfer bands in the visible may be introduced that depend on the concentration and nature of the acceptor molecule employed.

ISSN:0003-6951    

DOI:10.1063/1.1654317

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

A simple continuously tunable laser‐pumped dye laser is described. A dye solution in contact with a lateral face of a right‐triangular 90° prism, adjacent to the 90° corner, is pumped by laser light incident on the lateral face opposite to the 90° corner. A standing‐wave pump field is produced in the dye solution by the interference between the pump light that passes directly to the inner face in contact with the dye solution and the pump light internally reflected from the other lateral face adjacent to the 90° corner. The output wave‐length is determined by the spatial periodicity of the standing‐wave field and is easily varied by changing the angle of incidence between the pump‐laser beam and the prism face.

ISSN:0003-6951    

DOI:10.1063/1.1654318

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Efficient acoustic‐surface‐wave convolution, using 14.5‐MHz Bleustein‐Gulyaev waves, has been observed in a coupled PZT‐Si system. It has been found that the magnitude of the phenomenological nonlinear coupling constant of the convolver was four times as large as that of the basal plane of PZT‐8. The convolution output was controlled by the application of a voltage of several tens of volts.

ISSN:0003-6951    

DOI:10.1063/1.1654319

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

The energy of an isolated vertical Bloch line in high‐Qbubble materials is only a small fraction of the total wall energy. However, if there are so many Bloch lines along a domain wall that they are constrained to lie close to each other, their exchange energy becomes large. Calculations including this energy show qualitative agreement with the anomalous dependence of dimensions on bias field in certain bubbles and stripes in garnet films.

ISSN:0003-6951    

DOI:10.1063/1.1654320

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

The energy required to form an electron‐hole pair in gallium phosphide has been measured using GaPp‐njunction diodes made from high‐purity‐level GaP materials. The values of &egr;GaPfor several GaP diodes for alpha particles ranged from 6.35 to 6.75 eV, with an average value of 6.54 ± 0.13 eV at 300°K. This value is smaller than that obtained by Goldstein and is very close to the value of 6.56 eV calculated from the experimental relationship &egr; = 2.596Eg+ 0.714(eV), which was derived previously from the experimental values of &egr; for Ge, Si, GaAs, and CdTe.

ISSN:0003-6951    

DOI:10.1063/1.1654321

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Detection of the convolution of two signals which is produced by the surface‐wave nonlinearities is possible by employing several different methods. These methods, some of which are new and more efficient, are discussed, and a general explanation applicable to all cases is proposed.

ISSN:0003-6951    

DOI:10.1063/1.1654322

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

The behavior of a current filament in a gold‐dopedp+‐nSi diode was studied under a transverse magnetic field. The probe technique of electric potential was applied to measure the current distribution of the filament. By the action of the magnetic field, the filament was deformed and deflected toward one side of the diode. Moreover, a new ``filament instability'' which generates oscillation phenomena in the diode was observed.

ISSN:0003-6951    

DOI:10.1063/1.1654323

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

A new technique for measuring thermal emission rates of trapped minority carriers is experimentally demonstrated in reverse‐biasedn+psilicon diodes doped with gold, silver, and cobalt. It makes use of a monochromatic light of a proper photon energy to partially fill the traps with minority carriers (electrons). After the light is turned off, the thermal emission rates of the minority carriers are observed. A unique feature is that the thermal emission rates for both the minority and majority carrier traps can be accurately determined in just onep‐njunction, of either ap+norn+ptype.

ISSN:0003-6951    

DOI:10.1063/1.1654324

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Studies of the infrared‐pumped visible luminescence of NaYF4: Yb, Er show it to have at least twice the visible output of YF3: Yb, Er when pumped with a narrow‐band excitation source at the optimum frequency. It is also free from saturation effects until very intense excitation levels are reached. The mechanism for red upconversion appears to change with increasing excitation from a two‐step process to one involving a significant amount of three‐step upconversion, which change is accompanied by an increase in the response time for visible emissions.

ISSN:0003-6951    

DOI:10.1063/1.1654325

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Ultrasonic resonance, stress‐induced linear dichroism, and heat capacity measurements are used in an accurate determination of the Ne´el temperature of the cubic antiferromagnet KNiF3. All three techniques give a value of 246 ± 1°K forTN.

ISSN:0003-6951    

DOI:10.1063/1.1654326

出版商:AIP    

年代:1972

数据来源: AIP