ISSN:0003-6951    

DOI:10.1063/1.1754748

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

It is found that the spontaneous magnetization of disordered iron‐aluminum alloys changes the mode of theL20order‐disorder reaction from a second to a first degree transition. A new two‐phase field (&agr;m+ &agr;2n) has been found in the composition range 22.3 at. % Al to 25 at. % Al and this is responsible for many of the magnetic anomalies of these alloys. The microstructure of alloys heat‐treated in the (&agr;m+ &agr;2n)‐phase region can be controlled by an externally applied magnetic field which can also be used to determine quantitatively the ``antiphase'' boundary energy of theL20structure.

ISSN:0003-6951    

DOI:10.1063/1.1754749

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Direct observation of indications of self‐mode‐locking in the argon ion laser is reported. With losses introduced into the optical resonator, subnanosecond pulsation of the laser output is observed with a wide‐band photomultiplier.

ISSN:0003-6951    

DOI:10.1063/1.1754750

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

The drift velocity as a function of the electric field in gallium arsenide was measured directly by studying the response of a reverse‐biased Schottky‐barrieri‐n+GaAs photodetector to a step input of light. The photoresponse was dominated by trapping of electrons in theiregion. Analysis based on a simple model yielded the drift velocity—electric field characteristic in GaAs up to fields of 9000 V/cm. A region of negative differential mobility was observed to exist between a peak field of 2200 V/cm and an apparent valley field of 8000 V/cm.

ISSN:0003-6951    

DOI:10.1063/1.1754751

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A technique involving the use of a magnetic field in ``Q''‐spoiling a ruby laser cooled to 77°K is discussed. The laser rod is pumped in an intense, inhomogeneous magnetic field where gain is reduced by spatially inhomogeneous Zeeman splitting of the4A2ground multiplet. The rapid removal of this magnetic field produced a 500‐nsec period of enhanced amplitude spiking.

ISSN:0003-6951    

DOI:10.1063/1.1754752

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Optical frequency translation of pulses from a mode‐locked laser is described and demonstrated experimentally. The laser beam is passed through a crystal of LiNbO3whose refractive index is made to change sinusoidally at the mode‐locked laser round‐trip frequency (56 Mc/sec). A Doppler shift of the laser light results. Shifts of ±2.4 Gc/sec have been observed. The scheme may be capable of producing shifts as large as ±1000 Gc/sec.

ISSN:0003-6951    

DOI:10.1063/1.1754753

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Temperature dependence of the elastic wave losses is reported for bismuth germanium oxide, Bi12GeO20, a strongly piezoelectric crystal of point group 23. At 296°K and at 500 Mc/sec the attenuation, &Ggr;, is 0.11 dB/&mgr;sec and at 118 Mc/sec is 0.008 dB/&mgr;sec. At 4.2°K and at 500 Mc/sec, &Ggr; is 5 × 10−4dB/&mgr;sec and at 118 Mc/sec is 2.7 × 10−4dB/sec. At intermediate temperatures five loss peaks are observed, the origins of which as yet have not been determined. A shear wave velocity and the longitudinal wave velocity in the [110] direction are 1.77 × 105and 3.42 × 105cm/sec, respectively. The low elastic wave velocities and loss in Bi12GeO20, the low crystallization temperature, the piezoelectric coupling and the fact that it is cubic suggest possible advantages for device application involving storage of information at vhf and microwave frequencies.

ISSN:0003-6951    

DOI:10.1063/1.1754754

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

The evolution in time of laser‐induced fractures in bulk transparent materials such as glass is studied. Damage starts with a long, thin filament, collinear with the laser beam direction, almost simultaneously over its whole length. Damage then grows transversally to this direction, after the end of the incident laser pulse, and is accompanied by sparking. These observations favor damage mechanisms with short time constants, such as ionization or self‐trapping.

ISSN:0003-6951    

DOI:10.1063/1.1754755

出版商:AIP    

年代:1966

数据来源: AIP

ISSN:0003-6951    

DOI:10.1063/1.1754756

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Laser action on over sixty vibrational‐rotational transitions in the ground electronic state of nitric oxide is obtained by the dissociation of NOCl in a pulsed electrical discharge. The emission occurs between 5.84 and 6.43 &mgr;. The observed frequencies are fitted using the revised vibrational constants &ohgr;e= 1904.01 cm−1and &ohgr;e&khgr;e= 13.995 cm−1.

ISSN:0003-6951    

DOI:10.1063/1.1754757

出版商:AIP    

年代:1966

数据来源: AIP