摘要:

A new holography technique that permits direct visual observation of the relative phases of all parts of a vibrating surface is described. A small rotation is introduced between exposures of a stroboscopic hologram of a vibrating surface to produce a series of vertical fringes on the surface. The vertical fringes are distorted to the right or left by the surface deformation of the object under observation; the distortions form a record of the relative phases of all parts of the surface. The ambiguities existing in the interpretation of the shape of nonclassical modes from a conventional time‐averaged hologram are, thereby, resolved.

ISSN:0021-8979    

DOI:10.1063/1.1658090

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The phonon‐frequency dependence of S.B.S. steady‐state gain in dispersive liquids is derived by means of the hydrodynamic theory of absorption and dispersion of elastic waves and by means of the coupled wave equation method of the Tang theory of S.B.S. It turns out that the relaxation properties of the medium strongly affect the steady‐state behavior in C6H6and CCl4.

ISSN:0021-8979    

DOI:10.1063/1.1658091

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

It is shown that third‐order intensity correlations are sufficient to determine the time‐dependent intensity of aQ‐switched laser. As a consequence, all higher‐order correlations are related to the third and an expression for this relation is presented.

ISSN:0021-8979    

DOI:10.1063/1.1658092

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Sizable shifts in the oscillation frequency of a He&sngbnd;Ne laser with variations in the dc discharge current have been observed. The shifting effects are believed to be due principally to changes in the populations of the helium 23Slevel and the neon 1s5level. A simplified model is proposed for the approximate evaluation of these populations. A slightly modified version of the model, under regenerative conditions, is then used to evaluate the current shifting effects and the results are compared with experimental observations. The approach used is of sufficient generality to be applicable to most He&sngbnd;Ne lasers operating under optimum gain conditions. The results suggest that laser operation at 1.15 &mgr;, rather than 6328 Å, may considerably reduce the effects of current variations on the oscillation frequency. For constant pressure‐diameter product conditions, theory predicts that the current‐shifting effects will vary approximately inversely with tube diameter.

ISSN:0021-8979    

DOI:10.1063/1.1658093

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The relative sputtering rates of Ag and Cu from the Ag/Cu eutectic (60% Ag‐40% Cu by atoms) were measured by means of the spectroscopic emission technique. The targets were bombarded by 100‐eV Ar ions for target temperatures in the range of 80° to 285°C. At low target temperatures, the Ag and Cu sputtering yields vary with time of sputtering according to a simple sputtering model. However, at the higher temperatures surprisingly large differences were observed which could not be explained by a simple model. For example, Ag/Cu sputtering ratio variations greater than a factor of 10 were observed. After prolonged sputtering in the high‐temperature range, a thick surface layer (∼1 &mgr;) developed which was highly enriched in Cu. A model based on surface diffusion of Ag on Cu is proposed to explain the results.

ISSN:0021-8979    

DOI:10.1063/1.1658094

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Clean (211) and (110) surfaces of tungsten have been bombarded with inert‐gas‐ion beams in the energy range 40 eV–5 keV. Thermal desorption spectra of the trapped gas show patterns of peaks characteristic of the ion and the face bombarded. The results are comparable to those obtained previously for a (100) tungsten surface. In particular, all peaks below 1650°K are associated with desorption from sites within about 10 Å of the crystal surfaces, while the single peak above 1700°K is the result of isotropic diffusion of ions which have penetrated more than 10Å. Evidence is presented to support the hypothesis that the trapping sites consist of substitutional gas atoms and associated point defects.

ISSN:0021-8979    

DOI:10.1063/1.1658095

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Pulsed‐radiation‐induced current in crystalline and fused quartz was studied by using 5‐&mgr;sec pulses of electrons with an energy of 13 MeV and a current density of about 100 mA/cm2peak and a few &mgr;A/cm2average. The pulse shape of the induced current varied remarkably with time within a few minutes of irradiation and also with the temperature of the sample. The variation in shape showed a dependence on crystal orientation of the sample. The effect of the field of the internal space charge was found to be neglibible in the observed phenomena. A qualitative explanation is applied to part of the results in terms of an interaction between excited carriers and traps.

ISSN:0021-8979    

DOI:10.1063/1.1658096

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Transmission‐electron‐microscopy studies of neutron‐irradiated vanadium single crystals have revealed the presence of cylindrical regions of high damage concentration surrounding elongated fibrous precipitates. These precipitates have been identified as tetragonal V3B2and are oriented along⟨100⟩directions in the cubic vanadium lattice. The cylindrical damage shells are duplex in nature, consisting of a highly damaged inner region of about 1.3‐&mgr; radius and a less highly damaged outer region of about 2.6‐&mgr; radius. These two damage shells consist of small defect clusters produced by recoiling lithium ions and alpha particles, respectively, generated by10B(n, &agr;)7Li transmutation reactions. Post‐irradiation annealing at temperatures up to 1400°C eliminates the defect clusters and produces dislocation tangles and blocky precipitates in the inner shell and spherical cavities or bubbles in the outer shell. The precipitates in the inner shell are believed to be LiV2O5, while the bubbles in the outer shell are evidently formed by the agglomeration of helium atoms. Although spherical damage shells surrounding boron‐containing particles have been observed in several other irradiated metals and alloys, this represents the first known observation of nonspherical shells.

ISSN:0021-8979    

DOI:10.1063/1.1658097

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Deviations of focusons by repulsive and attractive forces at idealized surfaces have recently been proposed to account for ejection other than that exactly along close‐packed directions. The theory is here applied to actual faceted surfaces which are produced by ion bombardment. This treatment brings the deviation theory into very good agreement with experimental results. An earlier theory based on surface twinning to explain ejections parallel to some non‐close‐packed directions in the parent crystal is shown to be untenable.

ISSN:0021-8979    

DOI:10.1063/1.1658098

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

X‐ray diffraction studies and volumetric measurements in nearly perfect crystals of germanium are reported for samples exposed to successive fast‐neutron fluences above 1020neutrons/cm2at approximately 85°C. Volume expansions greater than 7×10−3were found and complementary lattice parameter results indicate the formation of defect regions having an average density which is considerably lower than that of the ordered structure. Anomalous fast‐neutron dose rate effects were observed by varying this parameter from 2.8×1013neutrons/cm2/sec to 3.5×1014neutrons/cm2/sec.

ISSN:0021-8979    

DOI:10.1063/1.1658099

出版商:AIP    

年代:1969

数据来源: AIP