Nonstigmatic input optics for toroidal grating monochromators.

  • Smith N.
  • Thiry P.

Ray-tracing computations show that the resolution of the 6m/160C TGM cannot be significantly improved by relaxing the requirement of stigmatic focussing. The results suggest a promising direction for future monochromator design employing cylindrical rather than toroidal gratings.

The dependence of modified chemical vapor deposition process (MCVD) equilibria on SiCl(4), GeCl(4) and O(2) concentrations as determined by the element potential method.

  • Hozack R.
  • Laudise R.
  • Mcafee K.
  • Walker K.

The high temperature equilibrium concentration of the gaseous species and of the deposited glass formed by the oxidation of the chlorides of silicon and germanium has been measured and compared with thermodynamic calculations. The recently redeveloped element potential method is used to minimize the Gibbs energy of the system and ...

Disorder and the fractional quantum Hall effect.

  • Gossard A.
  • Hwang J.
  • Paalanen M.
  • Tsui D.

The fractional quantum Hall effect is studied in the 2D electron gas of four GaAs-Al(x)Ga(1-x)As heterostructures. Localization due to disorder, known to give rise to the wide integral quantum Hall plateaus, is demonstrated to inhibit the fractional effect, which is observed only in the higher mobility samples.

Location of zeros in the complex temperature plane: Absence of Lee-Yang theorem.

  • Kurtze D.
  • Van-Saarloos W.

In extensions of the Yang-Lee theory to the complex temperature plane, it has often been assumed that the zeros of partition function would again fall in lines rather than in areas. Though this happens to be true for the isotropic Ising model, we point out that there is in general ...

Effects of annealing on plasma deposited a-Si:H films grown under optimal conditions.

  • Harbison J.
  • Kerwin T.
  • Sergent A.
  • Taylor C.
  • Wecht K.
  • Williams A.
  • Wilson B.

A comprehensive study is presented of the effects of isochronal annealing on the optical properties, spin density and hydrogen evolution of plasma deposited a-Si:H films grown under optimal conditions. Purely monotonic behavior is observed in all the properties of these films for annealing temperatures from 300C to 600C. Changes in ...

Equilibrium distributions of electric field in a cell with adsorbed charge at the surfaces.

  • Thurston R.

The asymmetry in the electric field distribution that results when an applied field is combined with the intrinsic field in the diffuse charge layer has been cited as a possible cause of the dc switching effect observed in liquid crystal displays based on bistable boundary layer configurations. Since the ratio ...

High quantum efficiency amorphous silicon photodetectors with picosecond response time.

  • Glass A.
  • Harbison J.
  • Johnson A.
  • Olson D.
  • Simpson W.

Amorphous silicon Schottky barrier photodetectors with internal quantum efficiencies of 36% and sampling ocilloscope limited response times of 40 ps (FWHM) have been fabricated. Utilizing ultra-thin films of rf glow discharge deposited a-Si:H carrier sweep-out was achieved in a new microstrip transmission line structure. The performance of these devices, for ...

Structure of Si(111)-7x7 II.

  • Mcrae E.

The previously proposed island-dimer model of the Si(111)-7x7 surface [E. G. McRae, Surf. Sci. 124, 106 (1983)] is modified to conform to wurzite-like surface stacking sequences implied by Rutherford backscattering results. The (7x7) surface is considered to have a triangular checkerboard structure in which the layer stacking sequences ...AaBbA and ...

Homoconjugation in radical cations.

  • Haddon R.
  • Roth H.

Recent studies of nuclear spin polarization effects in cyclopropane derivatives have provided considerable information on the structure as well as the spin and charge density distributions in this class of radical cations. In the present work we report an extension of the frontier MO/perturbation MO theory of homoconjugation to include ...

Fundamental detection limits in spectrophotometric analysis.

  • Harris T.
  • Williams A.

Recently developed methods for measuring small absorbances have potential application in trace element spectrophotometry. Achievement of low detection limits require compatibility between the chemical systems and the instrumental characteristics. The factors that determine compatibility are examined systematically and a new basis for comparing sensitivity is derived.

Physical properties of the first ferroelectric and antiferroelectric liquid crystal phases.

  • Brand H.
  • Cladis P.

The first ferroelectric liquid crystalline phase (in 8SI(*) (delta S-(+)-(4-(2'-methylbutyl) phenyl-4'-n-octylbiphenyl- 4 carboxylate) is reported and its physical properties are discussed. The close connection between the phase sequences of 8SI(*) and its racemate are established. Both compounds show a number of smectic phases above the newly discovered ferroelectric phase and ...

Material characterization of short-range conduction in metal- insulator-composites.

  • Etemad S.
  • Kuck V.
  • Moore W.
  • Quan X.

Elastomeric composites filled with metallized glass beads have been formulated and characterized for detachable chip carrier applications. These isotropic materials do not exhibit bulk conductivity but are conductive across thin sections. This is because the resistivity increases sharply by ten orders of magnitude as sample thickness is increased 1 to ...

Heat capacity studies near the smectic A-smectic C (smectic C*) transition in a racemic (chiral) smectic liquid crystal.

  • Goodby J.
  • Huang C.
  • Lien S.

Both chiral and racemic versions of 2-methylbutyl 4'-n-pentyloxy- biphenyl-4-carboxylate (2M45OBC) exhibit smectic A and smectic C phases. Both smectic-A-smectic-C and smectic-A-chiral smectic- C transitions are found to be mean-field like with a large sixth order term in the Landau free energy expansion. Our results also shed light on similarities and ...

Ultrapurification of nitrogen monitored by metastable transfer emission spectroscopy.

  • Mitchell J.
  • Wittman P.

Metastable energy transfer emission spectroscopy, a highly sensitive, convenient, and low cost technique, has been applied for online monitoring of nitrogen purity. Total oxygen impurity levels are detected sensitively by NO emission and carbon levels by emission from CN specie formed by chemiluminescent reactions of O and C specie with ...

Wavelength self-stabilization of coupled cavity semiconductor lasers.

  • Coldren L.
  • Ebeling K.

A simple wavelength control circuit is demonstrated that maintains single-longitudinal mode operation of coupled cavity semiconductor lasers over wide ranges of temperature. Photodetection properties of the lasing system itself are used for generating the discriminating signal for the feedback loop. No external optical elements like photodetectors or spectrometers are required.

Laser reliability assurance strategies: Part I: Discussion of the background, assumptions, and purposes of the proposed strategies.

  • Dixon R.
  • Gordon E.
  • Hatman R.
  • Joyce W.
  • Nash F.

We examine various strategies designed to assure the reliability of semiconductor lasers intended for an application in which the design lifetime is long, replacement of redundancy is impractical and the failure of even a few lasers could be crippling. The object is primarily to produce, by some screening procedure, a ...

Microdeformation losses of single-mode fibers.

  • Marcuse D.

We consider the scattering losses of single mode fibers that are caused by microdeformations such as microbends of the fiber axis and random fluctuations of the fiber core diameter. We consider single-mode fibers with step, parabolic and triangular (linear) refractive index profiles.

Spinodal decomposition in InGaAsP epitaxial layers.

  • Bonner W.
  • Cava R.
  • Dutt B.
  • Mahajan S.
  • Temkin H.

InGaAsP epitaxial layers emitting in the 1.25-137 micron wavelength region have been evaluated using transmission electron microscopy, X-ray diffraction and photoluminescence. Electron diffraction patterns show elongation of the 400 spots in the <100> direction and diffuse intensity on the low angle as well as on the high angle side. The ...

Properties of sintered-silver heat exchangers.

  • Busch P.
  • Cheston S.
  • Greywall D.

This paper reports measurements of surface area, electrical resistivity, and shrinkage performed on sintered-silver plugs made from several commercially available powders. These data are relevant to the design of heat-exchangers used for very- low-temperature experiments on liquid helium.

Charge injection transistor based on real-space hot-electron transfer.

  • Gossard A.
  • Hendel R.
  • Kastalsky A.
  • Luryi S.

We describe a new type of transistor based on hot-electron transfer between two conducting layers in an AlGaAs/GaAs heterojunction structure. One of these layers is the FET channel. The other layer (implemented as a heavily doped GaAs substrate) is separated from the channel by an Al(x)Ga(l-x)As graded barrier, with x ...