Materials Literature
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We combine a new synthesis with transient optical hole burning to observe and assign the size evolution (19 to 115 \AA{} diameter, \ensuremath{\sigma}5%) of a series of excited states in CdSe quantum dots. We observe an avoided crossing around the spin orbit energy in the hole spectra for \ensuremath{\sim}65 \AA{} dot…
Exchange of a β-methine unit for an N atom of a pyrrole ring of a porphyrin leads to a new type of porphyrin isomer, which is formed by condensation of pyrrole and P-tolylaldehyde. NiII ions are surprisingly coordinated by 1 as tetradentate ligand, that is through the three N atoms and the C atom of the inner cycle. T…
Using self-consistent field theory, we examine microphases of diblock copolymers and find, in addition to lamellar, hexagonal, and cubic phases, a stable gyroid phase which occurs between the lamellar and hexagonal ones. It terminates at a triple point, with a lamellar to hexagonal transition occurring in the weak-seg…
The birefringent and piezooptic properties of (MgSiF6) · 6H2O crystals are investigated. The second-order phase transition at Ti = 353 K is observed for the first time. It is shown that the investigated crystals possess properties characteristic of an incommensurate phase in the temperature range 298 to 353 K. The tra…
Abstract Polyisoprene (PIP) was found to react with trifluoroacetic acid (TFA) to give an adduct. Saponification of the ester gave a new alternating copolymer of ethylene and α‐methyl vinyl alcohol. TFA did not react with polybutadiene (PBD) under these conditions, thus providing a way to produce amphiphilic block cop…
The formation energies and electronic structures of three kinds of Si impurities in diamond are studied using the modified neglect of differential overlap method and the discrete-variational local-density-functional method with cluster models. The results show that it is difficult for all of the silicon impurities (in…
Single-phase (Sr1−x,K2x)Zr4(PO4)6 ceramic (with x=0.0–0.8) demonstrated values of thermal conductivity decrease with increasing potassium content to a minimum value at x=0.5, which suggests a maximum content of lattice defect, i.e., oxygen vacancy, at this composition. The thermal conductivity of the ceramic then incr…
Auger photoelectron coincidence spectroscopy (APECS) confirms that a substantial part of the low-energy tail of the ${\mathit{L}}_{23}$VV Auger lines of the 3d transition metals is due to intrinsic initial- and final-state shake-up/shake-off processes and not just secondary losses. Data were collected for the ${\mathi…
The lamellar semiconductors GaSe and InSe have been studied with k-resolved inverse-photoemission spectroscopy along two major symmetry directions (\ensuremath{\Gamma}\ifmmode\bar\else\textasciimacron\fi{} K\ifmmode\bar\else\textasciimacron\fi{} and \ensuremath{\Gamma}\ifmmode\bar\else\textasciimacron\fi{} M\ifmmode\b…
In order to optimize the magnetic properties of die-upset Pr-Fe-B magnets, we have systematically altered alloy compositions, including partial substitution of cobalt and neodymium, and low-level additions of gallium. In general, the remanences of Pr-Fe-B die-upset magnets were lower by ∼1 kG, and coercivities were hi…
Abstract The glass transition and melting behavior of poly(ether‐ester) multiblock copolymers with poly(tetramethylene isophthalate) (PTMI) hard segments and poly(tetramethylene oxide) (PTMO) soft segments are studied by differential scanning calorimetry (DSC) and small‐ and wide‐angle x‐ray scattering (SAXS and WAXS)…
Abstract New polyarylates and aromatic polyethers were synthesized from 1,2‐bis(4‐hydroxyphenyl)‐1,2‐diphenylethylene, and aromatic dicarboxylic acid chlorides and aromatic dihalides, respectively. The polyarylates having inherent viscosities of 0.28–1.05 dL/g were synthesized by either the two‐phase method or the hig…
We have calculated the contribution of the lowest-order vertex-correction diagram to the direct gap of silicon at the \ensuremath{\Gamma} point, taking into account the dynamic screening of the electron-electron interaction. Our best calculation yields a contribution of 0.12 eV. This result supports the assumption of…
Abstract The reaction of the alternating ethylene–carbon monoxide copolymer with Lawesson's reagent resulted in the conversion of 75% of the carbonyl groups to thiophene units. A few thioketone groups were also present in the derived polymer. A polymer with furan units in the backbone was formed upon treatment of the…
We have performed infrared absorption, continuous-wave photoluminescence, and nanosecond photoluminescence decay measurements to characterize stain-etched porous silicon. Stain-etched porous silicon samples were prepared by etching boron-doped crystalline silicon wafers in a solution of HF:${\mathrm{HNO}}_{3}$:${\math…
Abstract A new simulation model for the kinetics of long‐chain branching formed via chain transfer to polymer and terminal double‐bond polymerization is proposed. This model is based on the branching density distribution of the primary polymer molecules. The theory of branching density distribution is that each primar…
Accurate measurements of the polarized reflectance spectra of the series of isostructural organic conductors (TMTSF${)}_{2}$${\mathrm{ClO}}_{4}$, (TMTSF${)}_{2}$${\mathrm{PF}}_{6}$, (TMTTF${)}_{2}$Br, and (TMTSF${)}_{2}$${\mathrm{PF}}_{6}$ (where TMTSF denotes tetra-methy tetraselenafulvalene and TMTIF denotes tetra m…
Classical trajectory calculations were employed to study oxygenated (100) diamond surfaces. Atomic forces were computed from two types of potential energy functions, a quantum mechanical potential based on the semiempirical PM3 (parametric method number 3) Hamiltonian which was used to describe the central code core o…
The tight-binding method is used to calculate the electronic densities of states of various models of a-C. Both models generated using Tersoff's potential and quantum mechanically derived forces show \ensuremath{\pi} and ${\mathrm{\ensuremath{\pi}}}^{\mathrm{*}}$ states in the \ensuremath{\sigma} gap in agreement with…
Borosilicate glass films nominally containing up to 40 wt% ZnSe semiconductor crystallites have been successfully prepared on silica glass substrates by the sol-gel process. The influence of heat treatment on optical absorption, emission, and excitation properties was studied. On heating the films at temperatures from…