Materials Literature
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The CNDO/S3 molecular orbital model is applied to describe the electronic structure of aniline, (C6H5)NH2, emeraldine, (C6H5)N(C6H4)N(C6H4)NH(C6H4)NH2, its hydrogenated and dehydrogenated forms, and its singly and doubly protonated forms. The cation eigenvalue spectrum, i.e., density of valence states (DOVS), is found…
A recombinant plasmid carrying an 11 kb restriction-endonuclease-ClaI fragment of genomic DNA from Escherichia coli ML308 was constructed. This plasmid complements an aceA mutation. The plasmid encodes the structural genes of the glyoxylate bypass operon, namely malate synthase A (aceB), isocitrate lyase (aceA) and is…
X-ray scattering and electron-transmission microscopy of melt-spun Al-Si-Mn alloys reveal that the Al-Mn icosahedral phase itself can grow congruently over a range of composition varying from 16 to 20 at.?Mn, and Si atoms substitute Al atoms selectively. The Q dependences of linewidth \ensuremath{\Delta}Q suggest that…
Thin films of the C1b-phase Heusler alloy PtMnSb, prepared by rf sputtering and subsequent annealing, have been studied in order to assess the high magneto-optical Kerr effect of this compound. The room-temperature saturation magnetization (Ms) and coercive force (Hc) for PtMnSb thin films after being annealed at 500…
We present a model to explain the resonances in the photoemission cross section of a surface state as a function of photon energy. The model is based on an extension of the direct-transition model for bulk states, and should be applicable to a surface state with a long decay length. Energy broadening of the final stat…
Raman scattering and infrared studies are reported for the layer compound GaSe under hydrostatic pressures up to 4 GPa. The rigid-layer mode shifts towards higher frequencies with an initial pressure coefficient of 0.234 ${\mathrm{GPa}}^{\mathrm{\ensuremath{-}}1}$. The overall behavior is explained in terms of the vol…
Localized 3p excitations and their decay have been studied in 3d transition metals and their single-crystal oxides by using electron-energy-loss (EELS), photoemission, and resonant photoemission spectroscopies. Variation of the primary-electron-beam energy in EELS allows the resolution of threshold transitions from hi…
New series of ferroelectric liquid crystals with two chiral carbons or bulky molecular components at the chiral carbon are synthesized and are found to possess extremely large spontaneous polarization exceeding 2×10−7 C/cm2 and a dielectric constant larger than 7000. These compounds are stable and exhibit a novel diel…
We have found that decagonal quasicrystal and 10-fold twins of monoclinic ${\mathrm{Al}}_{13}$${\mathrm{Fe}}_{4}$ coexist in rapidly cooled Al-Fe alloy. The tenfold axis of the decagonal phase is parallel to the pseudotenfold [010] axis of the twins. There is good coincidence between the strong spots of the decagonal…
We have obtained Raman spectra of phase-I, -II, and -III ${\mathrm{KNO}}_{3}$ films 0.26 \ensuremath{\mu}m thick. The primary aim was to establish the physical mechanism for stabilization of the ferroelectric phase III in thin films. In bulk, phase III exists only as a reentrant phase stable from \ensuremath{\sim}113…
Epitaxial growth of SrO thin films onto Si(111) and (100) substrates by means of molecular-beam epitaxy has been demonstrated. The orientation relationships between epitaxial SrO and Si were found to be (111)SrO//(111)Si and [112̄]SrO//[112̄]Si, (100)SrO//(100)Si and [011]SrO//[001]Si. The composition of the grown fil…
The size dependence of the lowest electron-hole state in semiconductor microcrystals is calculated using the variational principle with a three-parameter Hylleraas-type wave function. For very small particles the Coulomb interaction may be treated as a perturbation. For larger particles the size dependence of the ener…
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…