Misfit-Dislocation Induced Surface Morphology of InGaAs/GaAs Heterostructures

The correlation between the surface cross-hatched morphology and the interfacial misfit dislocations in partially relaxed InGaAs/GaAs heterostructures was studied by means of atomic force microscopy and electron-beam induced current mode in a scanning electron microscope. A close correspondence between the misfit-dislocation network at the interface and the surface morphology shows that the cross-hatch development results primarily from the misfit-dislocation generation. Statistical analysis of the surface roughness reveals an anisotropy in strain relaxation of the epitaxial layers, which results from an asymmetry in the misfit-dislocation formation.     

Reaction between magnesium chloride and iron(III) chloride in tetrahydrofuran. The crystal structure of Di-μ-chlorodichloroiron(II) tetrakis(tetrahydrofuran)magnesium(II)

The direct reaction between magnesium chloride and iron(III) chloride in tetrahydrofuran (THF) yields the [MgCl(THF)₅][FeCl₄] complex (I). It is unstable and in reacting with THF undergoes reduction to produce the complex FeCl₂(μ-Cl)₂Mg(THF)₄ (II). Crystals of (II) are orthorhombic, space group Pbcn, with a = 9.18(1) b = 16.30(2) c = 15.85(1)Å. The structure was solved by the heavy atom method and refined by least squares to R = 0.053 for 1194 observed diffractometer data. The molecule is heterobimetallic with an Fe…Mg distance 3.455(3)ǎ and the Fe and Mg atoms are bridged by two Cl atoms.     

Effective action and cluster properties of the abelian Higgs model

We continue our program to establish the Higgs mechanism and mass gap for the abelian Higgs model in two and three dimensions. We develop a multiscale cluster expansion for the high frequency modes of the theory, within a framework of iterated renormalization group transformations. The expansions yield decoupling properties needed for a proof of exponential decay of correlations. The result of this analysis is a gauge invariant unit lattice theory with a deep Higgs potential of the shape required to exhibit the Higgs mechanism.Research partially supported by the National Science Foundation under Grant DMS-8602207 and by the Air Force Office of Scientific Research under Grant AFOSR-86-0229Alfred P. Sloan Research Fellow. Research partially supported by the National Science Foundation under Grants PHY-84-13285 and PHY-85-13554Research partially supported by the National Science Foundation under Grant PHY-85-13554     

Population equilibrium with support in evolutionary matrix games

In this paper we consider symmetric bimatrix games [A, A^T]. We use a matrix operator s(A), defined as the sum of the cofactors of the given matrix A, for finding the population equilibrium and its fitness in evolutionarily matrix games with all supported strategies, and to complete Bishop-Cannings Theorem.     

The crystal and molecular structure of Rh2(CH3CO2)4[HCON(CH3)]2—effect of ligands on metalmetal bonding

The structure of Rh₂(CH₃CO₂)₄(DMF)₂ {DMF = HCON(CH₃)₂} has been determined by single crystal X-ray methods. The compound crystallizes with eight formula units in a cell of dimensions: a = 29.438(7) Å, b = 7.978(2) Å, c = 20.279(5) Å, β = 113.20(4)°, V = 4377.5 ų, space group C2/c. The structure has been refined by full-matrix least-squares method to a final R = 0.030 for the 4156 observed data. Two Rh(II) atoms are linked by four acetate groups forming a dimeric unit, where the RhRh distance is 2.383(1) Å. The coordination sphere about each Rh atom is completed by a DMF molecule; the average RhO(DMF) distance is 2.296(3) Å.     

High resolution surface imaging of Co/ZrO2 catalyst by TOF-SIMS

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is a useful tool for the characterization of supported catalyst. Especially, the possibility of surface imaging appears very interesting. The images of not only elements distribution but also molecules or their fragments may be performed. Owing to the fast improvement of time-of-flight secondary ions mass spectrometers, obtaining the surface images with lateral resolution even below 100 nm is possible. The application of TOF-SIMS to the high resolution surface imaging of catalysts surfaces was shown. The influence of the preparation conditions of Co/ZrO₂ catalyst on the dispersion and composition of the active phase was investigated. The Co⁺/Zr⁺ and CoOH⁺/Zr⁺ intensity ratio values were calculated.     

X-ray structure of 3′,4-dimethylthio-3,4′-diquinolinyl sulfide

The title compound (C₂₀H₁₆N₂S₃) is monoclinic, witha=31.550(9),b=8.504(3),c=14.745(3) Å,=114.14(3)°,Z=8 and space groupC2/c. The structure was solved by direct methods and refined toR=0.038 for 3012 reflections. The molecule exists in an uncommon conformation. Two quinoline moieties are nearly perpendicular to each other (80.9(3)°). Both methylthio groups have different orientation (the 4-SCH₃ group is nearly perpendicular and the 3-SCH₃ is nearly coplanar to the quinoline moieties). Two pairs of sulfur atoms in ortho-positions remain in very close contact. The conformation of the molecule explains an unusual¹H NMR spectrum.Part XVI in the series of Azinyl Sulfides.