Materials Literature
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Vaporization measurements by the Knudsen technique and by mass spectrometry have been performed on the incongruently vaporizing titanium monoxide at the stoichiometric composition. Over this sample at 1806 K Ti(g) has a higher pressure than TiO(g) by a factor of about 3.5. The free energy difference between TiO(g) and…
Optical linear and nonlinear properties of single crystals of m-aminophenol, m-nitroaniline, m-chloronitrobenzene, and m-bromonitrobenzene have been studied. The second order optical susceptibilities have been measured with a Nd–YAG laser using a generalization of the Maker fringes technique to the case of biaxial cry…
Excitation profiles of depolarized modes (blg, b2g) in Ni etioporphyrin I exhibit marked 0–0 resonance Raman intensity upon Q-band excitation. By contrast, inversely polarized Raman scattering (a2g) is stronger with 0–1 excitation. Within the crude Born–Oppenheimer approximation, a theoretical model is presented which…
A theory for the photoemission from an electron gas due to the Drude energy absorption is presented. The theory, for both $p$- and $s$-polarized incident light, is based upon the three-step photoemission model and exhibits significant effects of the second-order matrix elements involved. Photoyields, energy distributi…
Stress gradients generated by electromigration in aluminum films were measured at 340 °C. The stresses were measured by combining x-ray topography to record the effects of the film stress and scanning electron microscopy to measure the information on the topographs. At the electromigration threshold the stress gradien…
Self-consistent pseudopotentials are used to investigate the electronic structure of $\ensuremath{\alpha}$-quartz. We present calculations for the band structure, electronic density of states, optical response functions, pseudocharge densities, and x-ray emission spectra. We find excellent agreement between theory and…
Optical-reflectivity data are presented for Rh and Ir for a photon energy range between 0.2 and 40 eV. Strong interband structures are observed in the calculated dielectric functions and optical conductivities, and these are discussed in terms of recent energy-band calculations. The dielectric functions are used to ca…
Analysis of the $H$-point magnetoreflection spectra of graphite is shown to be sensitive not only to the magnitude, but also to the sign of the Slonczewski-Weiss-McClure band parameter $\ensuremath{\Delta}$. The demonstration that $\ensuremath{\Delta}$ is small and negative provides a definite assignment for the large…
Raman scattering measurements on bulk amorphous As and thin-film sputter-deposited amorphous As and Sb indicate differences in the vibrational character of the systems. The polarization properties of amorphous As indicate quasimolecular character with differences between the bulk and sputtered material attributed to l…
We study the vibrational density of states of glassy $A{X}_{2}$ systems such as Si${\mathrm{O}}_{2}$ and Ge${\mathrm{S}}_{2}$ which consist of tetrahedra linked together to form a random network. We show that the higher-frequency modes can be well represented by a model with a single-nearest-neighbor central force. Th…
Normal-incidence reflectivity spectra in the photon energy range 4.5 to 14 eV have been measured on the basal faces of single crystals of the layered disulphides and diselenides of Ti, Zr and Hf. The spectra are interpreted in terms of chemical trends in the band structures, and based on this interpretation, models fo…
A structure analysis of the clean (001) surface of body-centred cubic iron by low-energy electron diffraction (LEED) is described. The surface was cleaned by a series of argon-ion bombardments followed by annealing treatments. The intensity analysis of 16 non-degenerate beams at three angles of incidence in the energy…
The two charge density wave (CDW) transitions in 4H b TaS 2 have been followed under pressure. The two transition temperatures were lowered when pressure was applied; the 315K atmospheric pressure transition associated with CDW formation in the octahedral layers was suppressed by 35 kbar, the 22K transition associated…
The 423K phase transition of CsCuCl 3 is attributed to a cooperative Jahn-Teller effect. Using results of the group-theoretical analysis of phonon modes, it is shown that helical atomic displacements in the low-temperature phase can be represented by a suitable linear combination of the polarization vectors of the Jah…
When a smetic-$A$ phase is composed of chiral molecules, it exhibits an electroclinic effect, i.e., a direct coupling of molecular tilt to applied field. The pretransitional behavior of the electroclinic effect in the $A$ phase is used to study the critical behavior near the second order, smectic-$A$---smectic-$C$ pha…
Triclinic crystals of hen egg-white lysozyme cross-linked with glutaraldehyde have been treated with various denaturants and found to be susceptible to x-ray structure analysis even after major conformational changes in the protein. Cross-linked crystals were isomorphous with the native form, and electron density diff…
Abstract The morphology of heterogeneous blends of polybutadiene (PBD) and EPDM was selectively varied by a change of either the rheology of the blend components during mixing or of the blend composition. Under a given set of mixing conditions, the blend system approaches a “steady state morphology”, which was found t…
Cross-linked triclinic lysozyme was denatured with sodium dodecyl sulfate. Removal of the denaturant resulted in a refolding of the protein to a conformation similar to but not identical with the native one. Three-dimensional x-ray diffraction data out to 3.2-A resolution were collected for two states in the refolding…
Abstract The reinforcement of elastomers by carbon black is governed by the morphology of the black and its physical and chemical interactions with the polymer. The latter are strongly affected by graphitization and surface oxidation. In modern rubber‐grade carbon blacks strong bonding of the polymer to the carbon bla…
We illustrate the usefulness of the extended x-ray absorption fine-structure effect for determining the chemical state, structure, and location of adsorbed species by a study of 0.2 monolayers of bromine adsorbed on graphite at room temperature. Bromine adsorbs as molecules with one atom fixed above the basal-plane he…