Materials Literature
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A new investigation of the optical properties of scandium is presented. Near-normal-incidence reflectivity measurements were performed from 0.22 to 5.5 eV on polycrystalline thin films evaporated in situ in ultrahigh vacuum. The reflectivity, from 0.22 to 35 eV, of the same samples after they had been exposed to air w…
Resonance Raman scattering (RRS) in CdSe is investigated in the region of the A excitonic transition. Three new Raman lines at 182, 195, and 208 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ are observed which become stronger than even the line due to the longitudinal optic (LO) phonon under appropriately resonant condit…
Transmission measurements on single-crystal ${\mathrm{SrTiO}}_{3}$ between room temperature and 1200?deC are reported. Urbach broadening of the absorption edge is observed at all temperatures. Below 200?deC the broadening is typical of the lowest indirect band gap. Above 400?deC the dominating broadening is due to the…
The optical properties of the transition-metal ions, ${\mathrm{Ni}}^{2+}$, ${\mathrm{Co}}^{2+}$, and ${\mathrm{Mn}}^{2+}$, in zirconium-barium-lanthanum-aluminum (ZBLA) fluoride glass are reported. Comparisons of the absorption spectra, luminescence spectra, and luminescence lifetimes for these ions in ZBLA and in ${\…
The hyperfine field, H hf , and the nuclear spin-lattice relaxation rate, 1/ T 1 , of 59 Co and 27 Al nuclei have been measured in the weak itinerant ferromagnets Y(Co 1- x Al x ) 2 . The temperature and magnetic field dependence of 1/ T 1 T has been found to be well described by the self-consistent renormalization (S…
The Cu+ ion impurity in a NaF host has been modeled using a finite cluster of ions to represent the crystal lattice. Several approximations to the lattice potential in the region of the cluster were compared to the exact Madelung potential. The error in the calculated nearest-neighbor distance for the pure host was fo…
The c-axis resistivity of highly oriented pyrolytic graphite has been measured from 2 to 300 K under hydrostatic pressures of up to 40 kbar. A resistivity peak near 40 K, typical for this type of graphite at ambient pressure, rapidly diminishes with increasing pressure but does not shift its position with respect to t…
Optical reflection and absorption spectra of SrTe and BaTe have been measured in the pressure range of 0 to 400 kbar at 300 K. Excitonic transitions related to the lowest direct gap in the rocksalt (B1) structure shift to lower energy with increasing pressure and are attributed to a Te 5p to Ba 5d (Sr 4d) transition a…
The effects of the local dielectric environment on the surface-plasmon resonances of annealed metal-island films are studied experimentally and modeled theoretically. Silver-island films were annealed to produce spheroidal shaped particles which exhibit well-resolved resonances in polarized, angle-resolved, absorption…
An interpretation model for low reflectivity in ultrahigh spatial-frequency holographic relief gratings is proposed. The model is based on the concept that the grating effective index, caused by grating ultrahigh spatial frequency, is graded in the depth direction and forms an antireflective constitution similar to th…
The proton spin lattice relaxation rate (1 / T 1 ) in the superconducting state of(TMTSF) 2 ClO 4 has been measured at zero magnetic field using the field cycling technique. It was found that the enhancement of 1 / T 1 just below T c , commonly observed in typical BCS superconductors, was absent and 1 / T 1 varied as…
Near-edge x-ray-absorption fine-structure studies of ${\mathrm{O}}_{2}$ chemisorbed on Ag(110) and Pt(111) surfaces near 100 K reveal different predissociation stages of molecular oxygen. ${\mathrm{O}}_{2}$ on Ag(110) exhibits only a ${\ensuremath{\sigma}}^{\mathrm{*}}$ resonance and resembles a single-bonded peroxo s…
We have measured the thermal conductivity of polymethylmethacrylate (PMMA), amorphous ${\mathrm{As}}_{2}$${\mathrm{S}}_{3}$, Ca-K nitrate glass, three ${\mathrm{SiO}}_{2}$-based glasses, and glycerol in the temperature range 30--300 K, using an ac technique that eliminates errors from blackbody radiation. This techniq…
It is shown how the results of low-temperature electrical and thermal conductivity measurements may be used to characterise and determine the defect structure of pristine and intercalated carbon fibres of various origins.
The aromatic (A) and quinoid (Q) forms of polythiophene (PT) have entirely different energy gaps: ∼0.5 eV for the quinoid form and ∼2 eV for the aromatic form, respectively. The energy gaps and stability of derivatives of PT are studied by total MNDO geometry optimization using energy band theory for the total energy…
The discrete scale invariance of quasi-periodic systems leads to a scaling relationship Omega =L -z f(L) between a characteristic dynamic variable Omega and length L, where f(L) is a periodic function of ln L. The dynamic exponent z can be calculated for diffusion, spin wave and phonon dynamics (where Omega is respect…
Radiation effects of X-rays in zircon (ZrSiO 4 ) single crystals were studied at RT, by analysing the kinetics and spectrum of the thermoluminescence between 20 degrees and 420 degrees C. The results indicate that some of the electrons produced by the irradiation are captured by Dy 3+ impurities apparently substitutin…
A 2D Ni-Cr quasicrystal displaying a twelvefold symmetry consists of a dodecagonal quasiunit cell (QUC) which is an intergrowth of ${\mathrm{Zr}}_{4}$${\mathrm{Al}}_{3}$ and ${\mathrm{Cr}}_{3}$Si structures. If the QUC is represented by a geometric point, then this quasicrystal can be described by a quasilattice deriv…
Abstract This paper is a review of leading research in the field of bacterial corrosion monitoring with specific emphasis on systems that transport liquids rather than gases. However, the principles of bacterial corrosion presented below are universal and independent of whatever media is transported through the pipeli…
The phase separation of a binary liquid mixture contained in a rigid porous medium has been investigated by study of the light scattered at 90\ifmmode^\circ\else\textdegree\fi{} from a porous glass rod containing a critical mixture of n-${\mathrm{C}}_{6}$${\mathrm{H}}_{14}$+n-${\mathrm{O}}_{6}$${\mathrm{F}}_{14}$. Evi…