摘要:

We report the second of a series of experiments on selective photoionization of mercury isotopes in which we show that radioactive atoms containing either isomeric form of the radionuclide197Hg can be selectively ionized in the presence of natural mercury isotopes by doubly resonant three‐step laser photoionization, and discuss its implications as a test case for nuclear‐isomer separation.

ISSN:0021-8979    

DOI:10.1063/1.336301

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The reflection from large absorbing scatterers having a complex refractive indexm=n1−i&kgr; (&kgr;>0), is determined by the Fresnel reflection coefficients. Lasing materials with inverted population or having a complex refractive indexm=n1+i&kgr; ‘‘reflect’’ the incident light with different coefficients, since internal reflections must be taken into account. The reflection coefficients for long cylindrical active scatterers are derived as asymptotic results of the theory of light scattering by large tilted cylinders and explained by polarization considerations. The resulting coefficients can be applied to active scatterers with very large reflection coefficients (negative extinctions).

ISSN:0021-8979    

DOI:10.1063/1.335916

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

An account of Brillouin scattering on thin dip‐coated polystyrene waveguides has been given. The behavior of the waveguide near the Bragg region is discussed. The Brillouin scattering observed in dip‐coated polystyrene films is attributed to the corrugations in the waveguide due to stress birefringence.

ISSN:0021-8979    

DOI:10.1063/1.335917

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The effects on the plasma and other conditions required to achieve population inversions between the quantum statesn=3 andn=2 of hydrogenlike ions caused by nonstatistical equilibrium fine‐structure sublevel densities are examined. Collisional and radiative transitions into and out of each of the fine‐structure sublevels (up to principle quantum numbern=5) are taken into account in a comprehensive collisional‐radiative code. Population inversions produced by both recombination and by photopumping from the 1sto 3pquantum states are examined. For electron densitiesNe≲1012Z7cm−3(whereZis the atomic number of the hydrogenlike ion), it is shown that inversions can be much more difficult to produce than is predicted by simple calculations assuming all sublevels are populated statistically.

ISSN:0021-8979    

DOI:10.1063/1.335918

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

We fabricated and life‐tested visible AlGaAs/GaAs channeled‐substrate‐planar‐type lasers and found that some are degraded within 100 h of operation. We investigated these using photoluminescence and transmission electron microscopic images. The characteristic features in photoluminescence images are dark defects that run parallel to the channeled stripe. Using transmission electron microscopy, we found that these dark defects are composed of precipitates, dislocation loops, and dislocation dipoles. In order to know the relation between these degradation phenomena and the thermal strain induced by lattice mismatch, we calculated the stress distribution in the semiconductor laser using the finite element method. According to this simulation, a stress concentration in the active layer arises near the edges of the channeled stripe where the volume dilatation is maximal. Combining the results of experiments and simulation, we concluded that interstitial atoms created by nonradiative recombination migrate to the edges of the stripe, and that ultimately dark defects appear near the edges of the stripe.

ISSN:0021-8979    

DOI:10.1063/1.335919

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Electromagnetic waves guided by the interface between two nonlinear media, and a nonlinear and a linear medium are investigated theoretically and numerically. Boths‐ andp‐polarized waves are analyzed and the guided wave power versus guided wave vector is evaluated for a variety of material conditions. The consequences of two different versions of the uniaxial approximation for thep‐polarized case are compared. The power‐dependent attenuation is approximately evaluated.

ISSN:0021-8979    

DOI:10.1063/1.335920

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The propagation characteristics of nonlinear waves guided by a metal film that is bounded on one or both sides by media characterized by an intensity‐dependent refractive index are discussed. The dispersion relations are solved numerically for both self‐focusing and self‐defocusing media with nonlinearities typical of InSb at a wavelength of 5.5 &mgr;m. In particular, the power dependence of the guided wave wave vector, of the field distributions, and of the wave attenuation are obtained for the multiple wave solutions allowed by the dispersion relations. In the appendix we evaluate the power dependence of the attenuation ofs‐polarized surface‐plasmon polaritons guided by a metal film.

ISSN:0021-8979    

DOI:10.1063/1.335921

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The laser output power of a traveling wave excitation TE N2laser in which the discharge was divided into several sections were calculated theoretically for the spark gap inductanceLsfrom 20 to 140 nH, the sectional length of the discharge from 5 to 50 cm, and the gas pressurePfrom 40 to 90 Torr. The experimental confirmation has also been conducted.

ISSN:0021-8979    

DOI:10.1063/1.335922

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

AQ‐switched, frequency‐doubled ruby laser has been used to generate wide bandwidth ultrasonic transients in aluminum and steel plates. Both longitudinal and shear waves were generated, resultant waveforms being dependent upon the irradiation conditions. Various designs of electromagnetic acoustic transducers were then used to detect these waveforms at the opposite side of the plate. The result is a method of ultrasonic inspection with potential in noncontact applications.

ISSN:0021-8979    

DOI:10.1063/1.335923

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

This paper examines the effective thermal conductivity of a misoriented short fiber composite. The analysis is based on the equivalent inclusion method for steady‐state heat conduction in composite which we have recently proposed. The present approach is unique in that it takes into account the interaction among fibers at different orientations. Closed form solutions are given for the thermal conductivity of a misoriented short fiber composite. Then, numerical results are presented to demonstrate the effects of volume fraction, fiber aspect ratio, and distribution function of fiber orientation on the thermal conductivity.

ISSN:0021-8979    

DOI:10.1063/1.335924

出版商:AIP    

年代:1985

数据来源: AIP