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71.
Thin films based on two very different metal-organic systems are developed and some nonlinear optical applications are explored.
A family of zinc complexes which form perfectly polar assemblies in their crystalline state are found to organize as uniaxially
oriented crystallites in vapor deposited thin films on glass substrate. Optical second harmonic generation from these films
is investigated. A simple protocol is developed for thein-situ fabrication of highly monodisperse silver nanoparticles in a polymer film matrix. The methodology can be used to produce
free-standing films. Optical limiting capability of the nanoparticle-embedded polymer film is demonstrated 相似文献
72.
P. Sreekumari Nair T. Radhakrishnan N. Revaprasadu A.S. Luyt 《Journal of Physics and Chemistry of Solids》2005,66(7):1302-1306
Composites of CdS nanoparticles confined in a polystyrene-co-maleic acid (PS-co-MAc) matrix have been prepared and characterized. It was shown that the acid groups of the co-polymer could be successfully used to control the aggregation of the nanoparticles, because they act as coordinate sites for Cd ions. UV-VIS measurements showed a blue shift of the absorption threshold, proving the presence of nanoparticles. An average size of the nanoparticles of about 4 nm is estimated from the change in band gap energy. Although the FTIR spectrum of the nanocomposite showed the presence of C-S bonds, a broad emission originating from surface recombination sites are noticed. DSC and TGA measurements revealed changes in thermal properties upon incorporation of nanoparticles. No thermal transition was observed in the nanocomposite, while the pure co-polymer exhibits a glass transition at 190 °C. In the presence of nanoparticles the onset of the thermal decomposition of the matrix is also shifted by 50 °C towards a higher temperature. 相似文献
73.
Twenty new complexes of chlorides and bromides of yttrium and lanthanides with the Schiff base 4-N-(4′-antipyrylmethylidene)aminoantipyrine
(AA) have been prepared and characterised. They have the general formula, [Ln(AA)2Cl3] and [Ln(AA)2Br2]Br where Ln = Y, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho and Er. Molar conductance studies indicate slight dissociation for the chloride
complexes and 1:1 electrolytic behaviour for the bromide complexes. The magnetic moments of all the complexes agree well with
Van Vleck values. The infrared spectra reveal that AA functions as a terdentate ligand in all these complexes coordinating
through the oxygens of both the carbonyl groups and the azomethine nitrogen. Electronic spectra of Nd, Ho and Er for the chloride
complexes and that of Pr, Nd, Ho and Er for the bromide complexes show weak covalency in the metal-ligand bond. 相似文献
74.
One of the innovative technological directions for the high-temperature superconductors has been persued by fabricating the
heteroepitaxial multilayer structures such as superconductor-semiconductor heterostructures. In the present investigation,
metal/superconductor/semiconductor (Ag/Tl-2223/CdSe) hetero-nanostructures have successfully been fabricated using dc electrodeposition
technique and were characterized by X-ray diffraction (XRD), full-width at half-maximum (FWHM) and scanning electron microscopy
(SEM) studies. The measurement of junction capacitance as a function of biasing voltage was used for the estimation of junction
built-in-potential (V
D) and to study the charge distribution in a heterojunction. The Mott-Schottky plots were measured for each junction in dark
and under the photo-irradiation. The effect of laser irradiation on C-V characteristics of hetero-nanostructure has been studied. 相似文献
75.
The phonon thermal conductivity values in Zn-doped GaSb are explained for hole concentrations ranging from 2 × 1017 to 4 × 1019 cm-3. The concentration dependence of thermal conductivity above 3 × 1018 cm-3 is similar to other doped materials and is explained by considering the scattering of phonons by free electrons (holes) given by Ziman and Kosarev and applying the screening effects suggested by Crossby and Grenier. The density-of-states effective mass is kept constant and the dilatation deformation potential is found to increase with hole concentration. For impurity concentrations less than 3 × 1018 cm-3, the thermal conductivity is found to increase with hole concentration. Since this concentration region is below the metal-insulator transition, the theory of scattering of phonons by holes bound to the impurity atoms explains the conductivity results. The values of acceptor hole radius and deformation potential constants are in agreement with the experimental values. 相似文献
76.
The polarographic behaviour of cobalt (II) in water and 50% methanol in the presence of various supporting electrolytes has been studied. The kinetic parameters and activation energy for the electrode process have been evaluated and compared. The results have been discussed on the basis of selective hydration of cobaltous ion at the electrode surface. 相似文献
77.
78.
79.
The anharmonicity factors of B2H6 and B2D6 have been calculated using Dennison’s method. Using the calculated harmonic wave numbers, the valence force constants have been obtained by the Wilson’s F-G matrix method. 相似文献
80.
N. T. Madhu P. K. Radhakrishnan Edna Williams W. Linert 《Journal of Thermal Analysis and Calorimetry》2005,79(1):157-161
The phenomenological, kinetic and mechanistic aspects of the nitrate, chloride, bromide and iodide complexes of cobalt(II) with 4-N-(4-antipyrylmethylidene)aminoantipyrine (AA) have been studied by TG and DTG techniques. The kinetic parameters such as activation energy, pre-exponential factor and entropy of activation were computed. The rate controlling process at all stages of decomposition is random nucleation with one nucleus on each particle (Mampel model) 相似文献