Materials Literature
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Convergent light observations have been made on three liquid crystalline substances with nematic and smectic phases. The nematic phase was observed to be uniaxial as expected, but smectic $C$ was found to be biaxial. The optic axial angle $2V$ for smectic $C$ was found to be on the order of 20\ifmmode^\circ\else\textd…
A least-squares refinement of x-ray diffraction data has been developed in which the parameters are the populations of atomic orbital products describing the molecular electron density distribution. The procedure is applied to alpha-oxalic acid dihydrate and cyanuric acid. Complementary structural information obtained…
Abstract The mechanism of the alternate copolymerization of phenyl isocyanate with ethylene oxide was investigated. Several experimental results show that this copolymerization proceeds according to an anionic coordinated mechanism. As for alternate copolymerization three mechanisms are generally considerable as follo…
The luminescence efficiency of the alkali metavanadates has been reported to increase by several orders of magnitude in the cation series from Na to K to Rb to Cs. Measurements of luminescence efficiency and decay time as a function of temperature show that maxima occur in the luminescence efficiency at 300, 200, and…
Using electron tunneling, we have made direct observation of a surface bound state of electrons localized in a narrow accumulation layer at the InAs-oxide interface. The Landau-level structure of the two-dimensional energy band, associated with the bound state, has been studied in a magnetic field up to 85 kG.
Azbel'-Kaner cyclotron resonance has been studied in arsenic at a frequency of 134 GHz. Cyclotron effective masses have been measured for magnetic field directions in the three principal crystallographic planes. The results are in general accord with the Fermi surface deduced from other experiments and from band-struc…
Magnetizations in the three main planes of a single crystal of manganese phosphide are measured at 4.2°K. Especially the b -axis magnetizations are studied in detail in the range of magnetic field up to 80 kOe at various temperatures. The screw-spin state of ferromagnetic spin state transforms to the state and than to…
Crystal structures and magnetic properties of Pt-Mn-Sn and Pt-Mn-Sb alloys have been investigated by means of X-ray analysis, magnetic analysis and nuclear magnetic resonance. It is found that the alloys with the stoichiometric compositions PtMnSn and PtMnSb are ferromagnetic and that the former has a structure of the…
Time-resolved spectra and luminescence decay-time measurements prove that at 1.8\ifmmode^\circ\else\textdegree\fi{}K the excitonic-molecule (EM) and free-exciton (FE) densities decay at different rates in pure silicon. The decay profile of the EM shows a postexcitation increase in luminesence followed by an approximat…
Expressions for the equation of state and the chemical potential are derived as functions of density and temperature for both a perfectly aligned and a completely isotropic fluid of rigid spherocylinders through consideration of the reversible work W(α, λ, ρ) necessary to add a scaled spherocylinder of radius α and cy…
The Auger-electron spectra in the intermediate- and low-energy range (0-1 keV) for many of the transition metals of periods 4-6 (specifically, Sc, Ti, V, Cr, Fe, Co, Y, Zr, Nb, Mo, Ru, Rh, La, Hf, Ta, W, Re, Ir, Pt, and Au) have been measured. In general, the spectra from elements in the same period of the Periodic Ta…
The infrared lattice-vibration spectra of ${\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{Al}}_{x}\mathrm{As}$ mixed crystals have been studied by measuring the room-temperature reflectivity at near-normal incidence in the 200-600-${\mathrm{cm}}^{\ensuremath{-}1}$ frequency range. Two distinct reststrahlen bands with freque…
The small-signal permittivity of the (100)-type 180° domain wall in BaTiO 3 is calculated relative to the signal-domain permittivity according to a previously-reported microscopic model of 180° domain walls in BaTiO 3 . A perturbation approach is developed which makes use of the known zero-field solutions of this doma…
The free radicals •Mn(CO) 5 and •Co(CO) 4 have been produced by the pyrolysis of Mn 2 (CO) 10 and Co 2 (CO) 8 in graphite flow reactors. The effusing molecular beams from these reactors were analyzed mass spectrometrically. Evidence is presented for the following equilibria[Formula: see text]From the temperature depen…
Single crystals of ferroelectric AgNa(NO 2 ) 2 were grown from aqueous solution containing proper amounts of NaNO 2 and AgNO 2 , and dielectric properties were measured. The dielectric constant along the b -direction ε b at 1 kHz shows a sharp maximum at the Curie point of 38°C. Above the Curie point, ε b obeys the Cu…
The interaction of Frankel excitons with optical phonons in molecular crystals is studied by means of a Green's function method in which the use of a canonical transformation allows most of the exciton–phonon interaction to be treated nonperturbatively. The self-energy of the Green's function is then expanded in terms…
ANDRES, K. (1968). Phys. Rev. 170, 614. BARRETT, C. S., MUELLER, M. H. & HITTERMAN, R. L. (1963). Phys. Rev. 129, 625. COPPENS, P. & HAMILTON, W. C. (1968). American Crystallographic Association Meeting, Buffalo, New York. Abstract G2. FISHER, E. S. & DEVER, D. (1968). Phys. Rev. 170, 607. HEATON, L., MUELLER, M. H. &…
Mössbauer spectra of 57 Fe in the nickel–zinc ferrite system (ZnO) x (NiO) 1−x Fe 2 O 3 have been obtained, at room temperature and at 77 °K, in zero magnetic field and also in a longitudinal magnetic field of 13.5 kG, covering the full range of zinc content. The dependence of the isomer shifts, line widths, quadrupol…
A complete theoretical and experimental analysis of the Maker fringes leads to the determination of accurate relative nonlinear optical susceptibilities in Si${\mathrm{O}}_{2}$, ${\mathrm{NH}}_{4}$${\mathrm{H}}_{2}$P${\mathrm{O}}_{4}$, and K${\mathrm{H}}_{2}$P${\mathrm{O}}_{4}$: ${{d}_{11}}^{2\ensuremath{\omega}}(\mat…
The electrical resistivities of single crystals of Ru${\mathrm{O}}_{2}$ and Ir${\mathrm{O}}_{2}$ in the temperature range 10-1000\ifmmode^\circ\else\textdegree\fi{}K are reported. It is found that electron-phonon and electron-electron interband scattering mechanisms account quantitatively for the observed temperature…