摘要:

The pressure and temperature dependence of the shear strength of grossly deformed solids conforms to a simple empirical law containing two parameters characteristic of the material. The empirical law and the constants appearing in it exhibit an interesting correlation with theoretical calculations of flow stress.

ISSN:0003-6951    

DOI:10.1063/1.1652552

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

Optical modulation near the intrinsic edge is observed in bulkn‐type GaAs using the Gunn effect at room temperature. A possible mechanism involves a shift of the absorption edge by the high electric field of propagating domains (Franz‐Keldysh effect). We also report some results on the production of extra carriers by photon‐initiated excitation which provides a means of changing the conductivity profile and current waveform of Gunn oscillators.

ISSN:0003-6951    

DOI:10.1063/1.1652553

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

Some new features of the step‐voltage transient behavior of an electron‐hole plasma injected via contacts into a long bar ofp‐type germanium are observed and explained theoretically. When the leading edge of the propagating plasma reaches the anode there is a cusp in the time derivative of the current, and thereafter the current increases with time essentially asconstant x[1 ‐ exp (−t/&tgr;)], where &tgr; is the recombination time.

ISSN:0003-6951    

DOI:10.1063/1.1652554

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

Detailed numerical analysis indicates that the density of states factor, previously predicted to occur for the exact transmission probability, only applies for carrier energies of a few meV. This casts doubt on the method used by Conley to derive the density of states in degenerate semiconductors.

ISSN:0003-6951    

DOI:10.1063/1.1652555

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

A gain of 20%/m and a power output of 50 mW have been measured on the 5s22D5/2→ 5p2P03/24416‐Å laser transition in Cd (II) using a single isotope of Cd114. The system was operated in a tubular furnace at temperatures in the range of 200°C with He as a buffer gas. The laser output with respect to He pressure, discharge current, and furnace temperature are discussed along with a proposed excitation mechanism. The system appears to have the prospect of being one of the most efficient, high power lasers operating in the visible region of the spectrum.

ISSN:0003-6951    

DOI:10.1063/1.1652556

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

An electron microscopic observation on a synthetic single crystal of magnetite has been carried out at a temperature range between 77°K and room temperature. It was observed that the ordered phases below the low‐temperature transition appear as finely divided stripes. The diffraction patterns in one of the stripes show the extra spots such as (00½), (100), (010), or (11½) in cubic indices. This indicates that the unit cell of the low‐temperature phase should be twice as large as that proposed by Verwey. The ordering scheme proposed should be more complicated than the Verwey order.

ISSN:0003-6951    

DOI:10.1063/1.1652557

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

The two‐photon fluorescence (TPF) technique for the display of picosecond pulses is analyzed. It is shown that TPF displays resembling those of picosecond pulses from mode‐locked lasers, but having reduced contrast, are produced by lasers in which mode locking is incomplete or absent. We report here new TPF experiments which provide further evidence for picosecond pulse output of dyeQ‐switched Nd:glass lasers. In addition, TPF observations with a single‐mode ruby laser are found to give contrast ratios in agreement with the general theory.

ISSN:0003-6951    

DOI:10.1063/1.1652558

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

Mode locking and ultrashort pulses have been produced in a giant‐pulse ruby laser with heated nitrobenzene (T> 110°C) or &agr;‐chloronaphthalene (T> 62°C) inside the optical resonator. 10−11‐sec pulses were observed with the two‐photon fluorescence technique.

ISSN:0003-6951    

DOI:10.1063/1.1652559

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

An optical analog of the electronic sampling oscilloscope is proposed, and preliminary experimental results are presented. The sampling pulses, ∼4 psec in duration, are produced by a mode‐locked Nd:glass laser. They are mixed in a KDP crystal with pulses of ∼800‐psec duration, from a mode locked He&sngbnd;Ne laser. The optical sum frequency is detected and displayed on a conventional oscilloscope. The pulse separations in the two lasers differ in such a way that, as time goes by, the sampling pulse scans the He&sngbnd;Ne pulse. There results, on the conventional oscilloscope, a sampled display of the He&sngbnd;Ne pulse.

ISSN:0003-6951    

DOI:10.1063/1.1652560

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

Photoconductivity at wavelengths up to 15 &mgr; at 77°K and up to 20 &mgr; at 4.2°K has been observed in Bridgman‐grown and subsequently annealed crystals of Pb1−xSnxTe which had carrier concentrations ranging from 2 to 8 × 1015cm−3with a mobility of about 3 × 104cm2/V‐sec at 77°K. Detectivity values generally were between 108and 109cm/W‐sec1/2at 77°K and greater than 1010cm/W‐sec1/2at 4.2°K. Photoconductive lifetimes of about 10−8at 77°K and higher temperatures and 10−6sec at 4.2°K were measured by means of light pulses from a GaAs diode laser.

ISSN:0003-6951    

DOI:10.1063/1.1652561

出版商:AIP    

年代:1968

数据来源: AIP