Materials Literature
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The dispersion relations for molecular-orientation fluctuations in a freely suspended ferroelectric smectic-$C$ liquid-crystal film have been determined by inelastic light scattering. The smectic-$C$ film geometry appears to be ideal for the experimental study of the space-time behavior of a two-dimensional orientatio…
Useful theories and models of the color and constitution of unsaturated organic compounds have been sought for more than a century. The promises of quantum chemistry have not yet been realized satisfactorily. The polymethine concept, a modern chemical theory of constitution, is an auspicious development.
The thermal dissociation rate of NF3 in mixtures of 5% and 10% NF3 in Ar has been measured behind incident shock waves over the temperature range 1330–2000 K. Dissociation rates were determined from postshock density gradients measured by laser beam deflection. The second order rate coefficient determined for NF3–Ar c…
Luminescence bands due to Cu + ions are found at 2.77 eV and 3.13 eV in CdBr 2 and at 1.75 eV, 2.85 eV and 3.30 eV in CdCl 2 . Thermal characteristics of these bands are analysed by rate equations. Optical extinction bands due to copper colloid are found at 1.90 eV and 2.10 eV in CdBr 2 and CdCl 2 , respectively. Exis…
A method is presented of solving for the vibrational Green's function of a silicon-dioxide Bethe lattice when it contains second-nearest-neighbor interactions. The method is used to find the density of states of a Bethe lattice constructed with a Keating Hamiltonian. The primary effect of the second-nearest-neighbor i…
The effect oj Cu Oil the hydrogell illduced cracking oj the pipe line steel was studied electrochemically and metallographically ill detail.It was Jound out that, if the addition oj Cu was more than 0.2 % , hydrogen illduced crackillg could be effectively suppressed.This is because addition oj Cu enhances the Jormatio…
Phonon spectra of organic linear conductors in the Peierls (semiconducting)phase are considered. It is shown that infrared absorption and Raman scattering can give information on the electron-phonon couplings of the various phonons. A rather sharp structure is predicted also above the electronic gap which is due to in…
The results of a set of experiments designed to delineate the nucleation rate, supersaturation, temperature surface for the system CaSO 4 •2H 2 O/H 2 O are reported. The data were obtained using the droplet technique coupled with in situ generation of SO 4 2− under the conditions that dS/dt was large during the early…
From studies of x-ray diffuse scattering it was found that a lattice instability near the metal-semiconductor transition in V${\mathrm{O}}_{2}$ occurs at the $R$ point with wave vector parallel to $\ensuremath{\Gamma} R$ and polarization vector parallel to the $c$ axis. This result is in agreement with predictions by…
The mean spherical approximation for a fluid of charged hard spheres of different radii is applied to the evaluation of diffraction patterns for the whole family of molten alkali halides. The ionic radii entering the model are determined from the liquid-state compressibility. The liquid-state radii are shown to be cha…
Oriented crystal growth on an amorphous substrate has been achieved using an artificially created surface-relief grating. Crystallites of KCl grown from a water solution onto a 320-nm spatial-period square-wave grating in SiO2 nucleated preferentially at vertical steps and grew with 〈100〉 directions parallel to the gr…
The phase transitions in Na-, K-, and Rb-tetracyanoquinodimethanide (TCNQ) single crystals have been investigated by the x-ray critical scattering technique. The intensities of superlattice reflections, which appeared below the phase-transition temperature ${T}_{c}$, decrease with increasing temperature toward ${T}_{c…
The theory of vibrational hyper-Raman scattering (inelastic second harmonic light scattering) is developed within the framework of quantum electrodynamics. The dynamical system comprises the molecule and the radiation field, coupled by multipolar interactions. In the present work, the electric dipole approximation is…
The tables of $l$-dependent ion-core radii ($l=0,1,2$) derived from free-ion quantum defects and previously presented by Simons and Bloch are extended to include halogens and the group-$\mathrm{I}\ensuremath{-}B$ metals (Cu, Ag, and Au). From these radii hybridized bond-orbital coordinates with $\ensuremath{\sigma}$ a…
In this study of metallic perovskites Mn 3 MX (M=metal, X=C, N) we emphasize the influence of the (outer) electron concentration on the sequences of crystallographic transitions, on the magnetic ordering temperatures and on the constant (Pauli-type like) part of the magnetic susceptibility. A great variety of observed…
The susceptibility of oxygen adsorbed on graphite indicates that magnetic transitions are present even in films of submonolayer thickness. This result contrasts with previous work on amorphous oxygen films and strongly supports the supposition that antiferromagnetic order can only be present simultaneously with config…
Rutherford back-scattering and X-ray photoelectron spectroscopy (XPS) have been used to study the stoichiometry and chemical composition of RF-sputtered thin films of ZnS. The results show that stoichiometry of the starting material is no guarantee of stoichiometry in the final film. Films grown in the normal way have…
Abstract IR. and Raman spectra of LnONO 3 (50–4,000 cm −1 , LnLa, Gd, Eu, and Dy) are reported and discussed. The low frequency region of the spectra reflects the cubic structure of these compounds. The dimensions of the cubic unit cells determined by X‐Ray powder diagrams are: 12.81 ± 0.05 Å for EuONO 3 , 12.69 ± 0.…
Abstract Poly‐ϵ‐caprolactam (Nylon‐6) wurde direkt in der Ionenquelle eines Massenspektrometers pyrolysiert. Bereits bei Temperaturen unterhalb 100°C heginnen dabei die im Polymeren enthaltenen cyclischen Oligomeren im Hochvakuum zu verdampfen und können massenspektrometrisch ohne vorherige Isolierung identifiziert we…
It is well known that sulfide stress corrosion (SSCC) and hydrogen induced cracking (HIC) or blistering could take place in the steel in wet hydrogen sulfide environment. It is said that SSCC could occur in relatively high strength steel having the hardness 20 to 22 in Rockwell C scale. [HR C > 20~ 22]1) Accordingly,…