Materials Literature
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The visible interaction of low-intensity ultrasonic waves with a nematic liquid crystal may be explained simply by the hypothesis of a torque tending to orient LC molecules perpendicular to the vibrations. It is shown how this torque can be related to anisotropic attenuation of ultrasound and minimization of propagati…
Measurements of the thermal impedance across copper-epoxy-copper sandwiches have been made over a temperature range of 0.05-10 K. The data are consistent with the suggestion that only low-frequency phonons contribute to thermal transport across the sandwich. As a result the apparent thermal boundary resistance at the…
We have measured the Auger, electron-energy-loss, and optical-transmission spectra of $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ and Na $\ensuremath{\beta}\ensuremath{-}{\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ from 0 to 45 eV and from 3 to 6 eV, respectively. Although Auger measurements were not ab…
A thin (∼400 Å) LPE In1−xGaxP1−zAsz ’’trap’’ on the p-type side of an InP junction [Eg(InP)−Eg(InGaPAs) ≡ΔE∼245 meV], is filled by injection to a high enough density to make it possible to observe confined-particle states and laser modes in a 70-meV (≳600 Å) range. The position of the modes is in good agreement with t…
Low-temperature Raman scattering results for stage 1, 2, and 3 graphite-alkali-metal intercalation compounds are reported for in-plane modes using the Brewster-angle back-scattering geometry. Detailed full spectra are presented for stage 1, 2, and 3 compounds of graphite-Rb at 77 K. Particular attention is given to th…
The complex dielectric constant has been measured at five audio frequencies over the temperature range 5.5-400 K for calcium fluoride doped with 13 different rare earths. Five relaxations are observed which are characteristic of rare earths in calcium fluoride. Two of the relaxations do not exist for large rare-earth…
The elastic constants K11, K22, and K33 of some members of two homologous series of nematic liquid crystals, the p,p′-di-n-alkyl and p,p′-di-n-alkoxy azoxybenzenes, are reported. Both K11 and K33 become greater with increasing alkyl chain length, while the ratio K33/K11 decreases along the series. For small alkyl chai…
The effects of compositional, vibrational, long-range positional, and topographical disorders upon the angle-resolved photoemission spectra of tightly bound valence electrons are investigated. In order to take into account the strong potential sensed by the electron in the vicinity of the atomic core, an augmented-pla…
Raman and far-infrared reflectivity spectra have been obtained for both stoichiometric and nonstoichiometric Ti${\mathrm{Se}}_{2}$ above and below the transition temperatures corresponding to formation of the $2{a}_{0}\ifmmode\times\else\texttimes\fi{}2{c}_{0}$ superlattice. In the normal phase above ${T}_{c}$ Raman-a…
A first-principles energy-band study of the metallic rutile phase of V${\mathrm{O}}_{2}$ using a general crystal potential and an expansion of the Bloch functions in a linear combination of atomic orbitals is reported. The results are compared with previous work and experimental optical, x-ray absorption and emission,…
The transport properties of the linear-chain metal Nb${\mathrm{Se}}_{3}$ are anomalous. Giant increases in the dc resistivity appear at 145 and 59 K, suggestive of charge-density-wave (CDW) formation. These anomalies show breakdown effects with applied electric fields as low as 0.1 V ${\mathrm{cm}}^{\ensuremath{-}1}$.…
The polarized reflectance at room temperature of potassium-tetracyanoquinodimethane (K-TCNQ) has been measured. Analysis using the Kramers-Kronig transforms gives the response functions (dielectric function and conductivity) between 300 and 23 000 ${\mathrm{cm}}^{\ensuremath{-}1}$. Attempts have been made to fit these…
The resonance of the Raman scattering by ${E}_{2}, {A}_{1T}, {E}_{1L}$, and ${E}_{1T}$ phonons, and several second-order features, has been studied for ZnO for photon energies between 1.6 and 3 eV. The results are interpreted with a dielectric theory based on the first and second derivatives of the dielectric constant…
Hair samples from 31 learning disabled and 22 normal children were analyzed for content of 14 elements. Significant group differences were determined and a discriminant function was completed which separated the groups with 98 per cent accuracy. Elevated lead and cadmium content in the learning disabled group is viewe…
The relevance of a high-temperature mechanism for vacancy migration, the double jump, has been established by molecular dynamics in Al and Na. Migration energies for single jumps are 0.42 \ifmmode\pm\else\textpm\fi{} 0.1 eV and 0.12 \ifmmode\pm\else\textpm\fi{} 0.02 eV, respectively, while for double jumps they are ab…
Thin-film lenses, mirrors, and diffraction gratings have been fabricated from electon-beam-generated masks. These masks were used to make iron oxide working masks for photolithographic fabrication of these passive components in Nb2O5 optical waveguides. The optical-waveguide characteristics of these components are dis…
Unusual band images observed by dynamical diffraction X-ray topography in nickel single crystals are elucidated by a model of very thin magnetic domains which extend obliquely through the thickness of the crystal. These thin domains have a magnetization direction which would cause free-pole formation on the crystal su…
New bands assigned to scandium hydride have been observed in emission in the green (5580 Å) and near infrared (8603 Å) regions. The identity of the carrier as ScH is established on the basis of the observed deuteride spectrum.
Polarized absorption spectra of centrosymmetric neodymium hexakis-antipyrine tri-iodide single crystals at 77 and 20\ifmmode^\circ\else\textdegree\fi{}K have been discussed. The spectrum is complicated by the appearance of a large number of vibronic lines. A phase transition destroying the inversion symmetry occurs be…
Abstract and Summary Lactitol was oxyalkylated with propylene or ethylene oxide. The resulting ether‐alcohols were transesterified with a series of fatty acid esters in order to produce long chain ether‐esters of lactitol. These compounds were found to be more water soluble than related lactitol derivatives prepared b…