摘要:

The line‐broadening effect of correlations between successive jumps of a Mo¨ssbauer atom is investigated. The ’’encounter model’’ originally developed for nuclear‐magnetic‐resonance diffusion studies is applied to describe temporal and spatial correlations which may cause significantly smaller linewidths than a random‐walk diffusion mechanism. This straightforward analytic generalization of the random‐walk results is capable of eliminating some of the earlier discrepancies between diffusion constants determined from radio‐tracer and Mo¨ssbauer experiments.

ISSN:0003-6951    

DOI:10.1063/1.89281

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A new reflective dichroic display device is described. The only components include a quarter‐wave retarder positioned between an aligned dichroic nematic liquid‐crystal display cell and a diffuse metallic reflector. This configuration allows both polarizations of incident light to be absorbed without affecting the polarizer‐free high brightness voltage activated state.

ISSN:0003-6951    

DOI:10.1063/1.89282

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Lithium ionic conductivity of Czochralski‐grown Li3N single crystals using electrochemical transport measurements is reported. The highest Li ionic conductivity was found perpendicular to the hexagonalcaxis, the anisotropy decreasing from two to one decade between 20 and 200 °C. Ambient Li ionic conductivity parallel to the Li2N planes of the layer structure was found to be &sgr;=10−3&OHgr;−1 cm−1with an activation energy of 0.25 eV. These values are comparable with the best data reported for Li &bgr;‐alumina single crystals.

ISSN:0003-6951    

DOI:10.1063/1.89283

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A high‐conductivity layer has been observed within the amorphous region of heavily implanted (6×1016cm−2of 2.7‐MeV31P ions) (111) surfaces of single‐crystal Si after 500 °C annealing. The conducting layer was at the projected range of the31P+ions, and its location was determined from spreading resistance measurements. Microscopic examination, Coates‐Kikuchi lines (SEM), and ion channeling showed that the conducting layer was within an amorphous region. Very‐large‐amplitude low‐frequency ir interference reflection fringes developed with the onset of the conducting layer. We suggest that the large fringes are related to the dispersion produced by a damped plasma. Simplified model calculations are presented. The high‐frequency interference fringes related to the implantation‐induced structural damage virtually disappeared after annealing at 600 °C but the low‐frequency ’’plasma fringes’’ remain. SEM and microscopic examination showed that the amorphous region had epitaxially recrystallized.

ISSN:0003-6951    

DOI:10.1063/1.89284

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Compositional changes of binary alloys and compounds have been observed (by Rutherford backscattering techniques) as a result of rare‐gas sputtering in the energy range 20–80 keV. After sputtering, the heavier components were generally found to be enriched in a surface layer whose thickness corresponded approximately to the range of the sputtering ion; the compositions of these enriched surface layers were independent of the mass and energy of the sputtering ions. This phenomenon of surface layer enrichment is interpreted as due to preferential sputtering from the surface in combination with defect‐enhanced diffusion.

ISSN:0003-6951    

DOI:10.1063/1.89285

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Optical waveguides have been fabricated by repeated alternate molecular‐beam depositions of ultrathin layers of GaAs and AlAs of from one to eight monolayers thickness per deposition. For an average core composition of 10% Al, optical losses of 2.0–2.5 cm−1have been measured between 1.1 eV and the band gap. Transmission electron micrographs prove that the layered structures of these waveguides corresponds closely to the programmed deposition sequences.

ISSN:0003-6951    

DOI:10.1063/1.89286

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

High optical sensitivity is observed in 0.1 wt% Ce‐doped strontium barium niobate (SBN) crystals in the absence of an external electric field. Only 5–10 mJ/cm2of incident 0.488‐&mgr;m radiation is required to produce 10% diffraction efficiency, while the energy to erase holograms from the 80% to its 1/ediffraction efficiency level is 30–40 mJ/cm2at the same wavelength. Holograms stored in Ce‐doped SBN persist at least one month (decay time constant) if kept in the dark at room temperature.

ISSN:0003-6951    

DOI:10.1063/1.89287

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A spatially coherent oscillator at 337 nm was made by placing a nitrogen discharge inside an unstable resonator of high magnification. An energy of 205 &mgr;J was achieved, with 100 &mgr;J in a diffraction‐limited spot. The diffraction‐limited coherence could be maintained during amplification to 1.0 mJ in a second discharge.

ISSN:0003-6951    

DOI:10.1063/1.89264

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A scalable uv‐preionized transverse discharge XeF laser has been operated at pressures up to 5 atm. uv output energies in excess of 250 mJ with a minimum pulse duration of less than 20 ns have been obtained from an active volume of 0.18 liter.

ISSN:0003-6951    

DOI:10.1063/1.89265

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The kinetics of the purely chemical production of nonequilibrium concentrations of Cl atoms from the ClO2/NO chain reaction is discussed. It is shown that this chemical system is suitable for producing Cl atoms to pump a cw HCl laser and that there are three modes of accomplishing the prepumping chemistry. A hybrid HCl/CO2laser was operated using this chemistry which gave 7 mW output power at 10.6 &mgr;m. A transverse flow HCl laser was operated having a multiline output power of 13 W and a chemical efficiency of 8%. The three modes of accomplishing the chemistry were demonstrated with a transverse flow HCl laser.

ISSN:0003-6951    

DOI:10.1063/1.89266

出版商:AIP    

年代:1977

数据来源: AIP