Materials Literature
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Transmission-electron microscopy of chiral 4-(2-methylpentylphenyl)-4\ensuremath{'}-hexyloxybenzoate (CE4) quenched from its cholesteric and blue phases (BP) I and III are presented. Images of cholesteric and BP I are consistent with an earlier study of similar compounds. CE4 quenched from its BP III is a spaghettilik…
Nonequilibrium periodic textures are induced by a magnetic field $H$ applied to the aligned uniaxial (negative diamagnetic anisotropy) lyotropic nematic phase of the potassium laurate-decanol-water system. Two cases are studied: a rotating field and a static field. For the rotating field a transient one-dimensional st…
We study the plasma excitations of an array of two-dimensional electron-gas layers arranged in a Fibonacci sequence. The plasmon spectrum is analyzed by a transfer-matrix method. It is shown that the spectrum is always "critical," i.e., it corresponds to neither extended nor localized plasmon states. This property is…
In binary liquid mixtures, the growth of wetting layers can be limited by diffusion. At complete wetting, the distance $l$ between the interfaces bounding the layer is shown to grow as $l(t)\ensuremath{\approx}{A}_{*}{t}^{\ensuremath{\theta}}$ for large times $t$ where ${A}_{*}$ increases near the consolute point. In…
We have reconsidered the problem of the critical layer thickness hc for growth of strained heterolayers on lattice-mismatched substrates, using a new approach which allows us to determine the spatial distribution of stresses in a bi-material assembly and include the effects of a finite size of the sample. The possibil…
The heat capacity C(T) of quenched and annealed samples of bulk As 2 S 3 glasses has been measured in the temperature range 1.5 to 20K, and a far-infrared laser has been used to determine the room-temperature absorption alpha ( nu ) as a function of frequency nu in the range 0.6 to 3 THz (20 to 100 cm -1 ). Both C(T)/…
The authors have evaluated the temperature dependence of the tight-binding transfer integral between neighbouring cation molecules for some representative compounds of the (TMTSF) 2 X and (TMTTF) 2 X families using their recently determined low-temperature and/or high-pressure crystallographic structures. The changes…
The superstructure caused by the charge density wave (CDW) of the nearly commensurate (N. C.) phase in 1TTaS2 is studied in atomic scale by a high resolution electron microscope with image processing system and a selected area electron diffraction method. It is found that the super-structure of the N. C. phase, which…
The three dominant cathodoluminescence bands in amorphous SiO2 with maxima at 1.9, 2.7, and 4.3 cV are identical to bands seen in photoluminescence (PL) spectra of irradiated or oxygen-deficient amorphous SiO2. On the basis of the previous PL work these cathodoluminescence (CL) bands can be attributed to non-bridging…
Bi12GeO20 (BGO) and Bi12SiO20 (BSO) single crystals doped with Al, Ga, P, Pb, Or, Nd, Zn, Fe, and Eu are grown from the melt in good optical quality. The segregation coefficients of the dopants range from 0.1 to 5. The undoped crystals are yellow; Al, Ga, and P bleach the crystals and increase their dark conductivity.…
The nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) of the 181 Ta nuclei have been made on 1 T -TaS 2 at 4.2 K in order to get detailed information on the superlattice structure in the commensurate charge density wave state of this material from a microscopic viewpoint. The NMR ane NQR spectra…
Temperature dependence of the dielectric constant, D – E hysteresis loops and pyroelectric charges in Sr 2 Nb 2 O 7 have been studied in the temperature range from 4.2 K to 300 K. In addition to the well known ferroelectric transition at 1615 K, another ferroelectric phase transition occurs at T 0 ∼100 K. The dielectr…
The effect of high magnetic fields on the electronic structure of some quasi-one-dimensional systems with charge- or spin-density waves is examined. Because of the specific anisotropy of the system, small electron and hole pockets created by the density wave can be destroyed by the presence of a magnetic field. This p…
The surface-enhanced Raman scattering (SERS) from thin films formed by p-nitrobenzoic acid (PNBA) adsorbed onto silver island films has been investigated. SERS spectra obtained using low laser powers were very similar to the normal Raman spectra of the sodium salt of PNBA and were characterized by strong bands near 16…
We have investigated the dynamical behavior of twisted nematic crystals quenched from an isotropic phase into a nematic phase. In such a system the collective motion of an assembly of disclination can be observed and a dynamical scaling law was found. The u-field theory developed by Ohta, Jasnow and Kawasaki was appli…
Adsorption of CO and the coadsorption of CO with low coverages of K on Fe(111) at temperatures as low as 83 K have been studied with low energy electron diffraction (LEED), thermal desorption spectroscopy (TDS), and high resolution electron energy loss spectroscopy (HREELS). The results indicate that CO fills three di…
The experimental carbon Auger line shape for graphite has been obtained, corrected for the effects of the secondary-electron background and extrinsic losses, and placed on an absolute energy scale through the use of photoelectron measurements. The resulting line shape is compared to a model which consists of the self-…
We have examined the question of whether excess low-frequency (1/f) noise in metal films arises in the bulk or at the sample surface. We measured the noise in continuous Cr films with 80 A\r{}2600 A\r{}, where t is the film thickness. Establishing that the relative noise intensity ${S}_{\ensuremath{\rho}}$(f)/${\ensur…
Based upon a superlattice model for graphite intercalated compounds (GIC's), we present in this paper a detailed calculation of the lifetime of a conduction electron in a stage-1, acceptor-type GIC. Both intraband and interband processes, as well as intervalley processes, are included in this calculation. We find that…
Pyrrole-based conducting polymers have been investigated by high-resolution electron-energy-loss spectroscopy and by electron diffraction. The evolution of the \ensuremath{\pi}-electron band structure as a function of the oxidation can be explained in terms of a bipolaron model. Strongly oxidized polypyrrole is not a…