摘要:

Gold films (200–500 Å) have been evaporated onto air‐ and vacuum‐cleaved polar surfaces of ZnO. While the films grown on the air‐cleaved surfaces are polycrystalline in a temperature range from 20 to about 450°K, the films grown on the vacuum‐cleaved surfaces are perfect (111) single crystals in the investigated temperature range from 20 to 700°K. The low‐temperature epitaxy can be explained by the strong binding energy between overgrowth and substrate, caused by the polarity of the substrate.

ISSN:0003-6951    

DOI:10.1063/1.1653186

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Infrared photoemission fromp‐type silicon has been observed with a threshold of 1.1 eV. The surface of the sample has been activated to a state of effective negative electron affinity. The escape depth for thermal photoelectrons is 5.5&mgr; (microns) and surface escape probability is 0.18.

ISSN:0003-6951    

DOI:10.1063/1.1653187

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Short‐time heat treatments in a H2flow, and under an As vapor, have been performed onn‐type andp‐type GaAs crystals. Acceptors are created at the surface and proceed to the interior. The changes in carrier concentration as function of As vapor pressure showed the acceptors to be associated with As vacancies.

ISSN:0003-6951    

DOI:10.1063/1.1653188

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Visualization of ultrasonic wavefields incident on an optically reflecting surface is effected by coherent optical detection of the deformations of this surface. A Twyman‐Green interferometer is used in which the orthogonal reference beam is frequency‐offset with an ultrasonic light modulator. The recombined light field is scanned with an image dissector, and the resulting image displayed on a kinescope.

ISSN:0003-6951    

DOI:10.1063/1.1653189

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Long pulse laser emission is obtained from Rhodamine 6 G using cyclooctatetraene to quench the triplet state of the dye. It is found that cyclooctatetraene is at least as effective as molecular oxygen.

ISSN:0003-6951    

DOI:10.1063/1.1653190

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Threshold average electric fields of approximately 1 kV/cm are experimentally observed for large‐amplitude sinusoidal current oscillations at 77°K. These oscillations are different from previously reported oscillations inn‐type Ge. The 0.25–1.0 A (rms) oscillations occur at frequencies near 1 GHz. The frequency is found to decrease with increasing electric field and to be relatively independent of magnetic field.

ISSN:0003-6951    

DOI:10.1063/1.1653191

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

An optical phase grating has been generated by introducing surface waves on one face of a Fabry‐Perot interferometer. This device called SWIM (Surface Wave Interference Modulator) produces a diffraction pattern at the Fourier plane in which the light intensity of the first‐order modulated beam is 1% of the zeroth order with an acoustic power of 0.85 mW/mm beam width. First‐order intensities greater than 10% have been realized; however, the process is not linear at this modulation depth.

ISSN:0003-6951    

DOI:10.1063/1.1653192

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Measurement of potential distributions versus distance in gold‐doped germanium double‐injection diodes have been made and compared to the Ashley‐Milnes theory. Estimates of capture cross sections of the gold centers based on these measurements have been calculated to be&sgr;n0=10−16 cm2and &sgr;n−= 3 × 10−17cm2at 77.2°K.

ISSN:0003-6951    

DOI:10.1063/1.1653193

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

When a laser beam propagates in an absorbing medium flowing transverse to the direction of propagation, the beam may be deflected and distorted by the self‐induced thermal lens, which results from the absorbed laser beam energy. Experiments have been carried out examining the thermal bending and distortion of a cw CO2laser beam in a 1‐m‐long wind tunnel. At the onset of the convection‐controlled thermal distortion, the peak intensity of the laser beam is reduced and shifted into the wind. For experimental conditions leading to severe thermal distortion of the beam shape, it is observed that the deflection and decrease in the peak laser beam intensity tend to approach a constant value. This result is interpreted as a saturation of the convection‐controlled, self‐induced thermal lens which occurs when the thermal distortion is large and accompanied by a significant reduction in the minimum characteristic beam dimension. In the experiments reported, the path length and minimum characteristic beam dimensions associated with the thermal distortion were such that diffraction effects may be involved together with the thermal lens process in producing the observed saturation effect.

ISSN:0003-6951    

DOI:10.1063/1.1653194

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A point‐contact (SQUID) magnetometer was used inside a shielded room to record the magnetic field of the human heart, without noise‐averaging. The resulting magnetocardiograms, with the peak signal at about 3 × 10−7G had a noise level of about 1 × 10−9G (rms, per root cycle). They approach good medical electrocardiograms in clarity, and are an order‐of‐magnitude improvement in sensitivity over previous magnetic detectors of the heart. These results suggest new medical uses for this magnetometer.

ISSN:0003-6951    

DOI:10.1063/1.1653195

出版商:AIP    

年代:1970

数据来源: AIP