Materials Literature
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The sensitized triplet-triplet annihilation (TTA) of 9,10-dimethylanthracene (DMA) upon selective excitation of [Ru(dmb)3]2+ (dmb = 4,4'-dimethyl-2,2'-bipyridine) at 514.5 nm in dimethylformamide (DMF) resulted in upconverted and downconverted DMA excimer photoluminescence. The triplet excited state of [Ru(dmb)3]2+ is…
The complexity of intermolecular interactions in polymer-nanoparticle systems leads to spatial variations in structure and dynamics at both the meso- and nanoscale. Much of this behavior is manifested in properties such as the glass transition and the viscosity. Incoherent neutron scattering measurements of C60-polyme…
We report on a facile route for the immobilization of silver nanoparticles (Ag NPs) onto the pH-responsive poly(2-vinylpyridine) (P2VP) brushes. The process involves chemical grafting of P2VP chains on the underlying substrate in brush conformation followed by the in situ synthesis of Ag NPs via chemical reduction of…
The self-assembly (SA) of amphiphilic block copolymers (poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)) was investigated in dispersions of single-walled and multiwalled carbon nanotubes (SWNT and MWNT, respectively) as a function of temperature. Differential scanning calorimetry (DSC) was used for cha…
We have prepared poly( N-isopropylacrylamide (IPAAm)- co-2-(dimethylamino)ethylmethacrylate (DMAEMA)) brush-grafted silica bead surfaces through surface-initiated atom transfer radical polymerization (ATRP) using the CuCl/CuCl 2/Me 6TREN catalytic system in 2-propanol at 25 degrees C for 16 h. The prepared temperature…
A Drude-Boltzmann theory is used to calculate the transport properties of bilayer graphene. We find that for typical carrier densities accessible in graphene experiments, the dominant scattering mechanism is overscreened Coulomb impurities that behave like short-range scatterers. We anticipate that the conductivity $\…
We present Maxwell equations with source terms for the electromagnetic field interacting with a moving electron in a spin-orbit coupled semiconductor heterostructure. We start with the eight--band ${\bm k}{\bm p}$ model and derive the electric and magnetic polarization vectors using the Gordon--like decomposition meth…
Synchrotron infrared measurements were conducted over the range 100 to 8000 cm-1 on a self-doped LaxMnO3-d (x~~0.8) film. From these measurements we determined the conductivity, the effective number of free carriers, and the specific phonon modes as a function of frequency. While the metal-insulator transition tempera…
A new class of boron-dipyrromethene (BDP or BODIPY) dyes was obtained by phenanthrene fusion to the beta-pyrrole positions, absorbing in the wavelength range of important laser sources. Despite a 'propeller-like' distorted structure in the crystalline state, the chromophore absorbs (log epsilon > or = 5) and fluoresce…
High-pressure resistivity and x-ray diffraction have been measured on La0.85MnO3-d. At low pressures the metal-insulator transition temperature (TMI) increases linearly with pressure up to a critical pressure, P* ~ 3.4 GPa, which is followed by reduction of TMI with increasing pressure. Analysis of the bond distances…
We have performed X-ray magnetic circular dichroism (XMCD) and valence-band photoemission studies of the diluted ferromagnetic semiconductor Zn 1- x Cr x Te. XMCD signals due to ferromagnetism and paramagnetism and/or superparamagnetism were observed at the Cr 2p absorption edge. Comparison with atomic multiplet calcu…
We study the charge density distribution, the electric field profile, and the resistance of an electrostatically created lateral p-n junction in graphene. We show that the electric field at the interface of the electron and hole regions is strongly enhanced due to limited screening capacity of Dirac quasiparticles. Ac…
Wool and silk were dissolved and used for the preparation of blended films. Two systems are proposed: (1) blend films of silk fibroin and keratin aqueous solutions and (2) silk fibroin and keratin dissolved in formic acid. The FTIR spectra of pure films cast from aqueous solutions indicated that the keratin secondary…
Nanoshell arrays have recently been found to possess ideal properties as a substrate for combining surface enhanced raman scattering (SERS) and surface enhanced infrared absorption (SEIRA) spectroscopies, with large field enhancements at the same spatial locations on the structure. For small interparticle distances, t…
The dimensionless thermoelectric figure of merit (ZT) in bismuth antimony telluride (BiSbTe) bulk alloys has remained around 1 for more than 50 years. We show that a peak ZT of 1.4 at 100 degrees C can be achieved in a p-type nanocrystalline BiSbTe bulk alloy. These nanocrystalline bulk materials were made by hot pres…
The design andsynthesis of basic porphyrin building blocks for the con-struction of highly ordered systems often require incorpo-ration of different peripheral substituents. The synthesis ofporphyrins bearing specific patterns of functionality is stillchallenging task in spite of the ample presence of reportedprocedur…
The spin Hamiltonian (SH) parameters g factors g ‖ , g ⊥ and the hyperfine structure constants A ‖ and A ⊥ for the tetragonal Cu 2+ centers (i.e., [ CuX 4 ( H 2 O ) 2 ] clusters) in NH 4 X ( X = Cl, Br, I ) are theoretically investigated by means of the diagonalization procedure of complete (10×10) energy matrix (DPCE…
Lead(II) 4,4,4-trifluoro-1-phenyl-1,3-butandionate (TFPB−) complexes with 1,10-phenanthroline (phen) and 2,2′-bipyridine (2,2′-bipy), [Pb(L)(TFPB)2], have been synthesized and characterized by elemental analysis, IR-, 1H NMR spectroscopy and studied by X-ray crystallography. The self-assembly of [Pb(L)(TFPB)2] complex…
Current transport in carbon nanotube field effect transistors (CNT-FETs) has been modeled from charge distributions and the potential inside the carbon nanotube. Analytical equations describing I-V characteristics of the CNT-FETs have been obtained from the combination of diffusion and drift mechanisms in the channel…
We report the synthesis and evaluation of thermal behavior of two new mesogenic homologous series of liquid crystalline compound containg 1,2,4-triazole and isonicotinic acid ring at the terminus of the molecule viz. 4-[(4H-1,2,4-triazol-4-ylimino) methyl] phenyl 4-alkoxybenzoate and 4-(2-isonicotinoylcarbonohydrazono…