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91.
Awadhesh Mani J. Janaki Soubhadra Sen A. Bharathi Y. Hariharan 《Solid State Communications》2008,146(9-10):391-394
The temperature dependent specific heat studies of a Ru substituted Fe1−xRuxSi Kondo Insulating system has been carried out in the 77 to 300 K range. The specific heat has been analyzed based on contributions from an electronic part and a lattice part. For the electronic part a Gaussian density of states model, which incorporates the effect of correlation, band structure and disorder in its defining parameters is used. The lattice part of specific heat is described in the Debye model. Parameters that define the electronic density of states and the Debye temperature are extracted from fits of the temperature dependent specific heat data and are compared with earlier resistivity measurements that employed a similar analysis. 相似文献
92.
Positron lifetime has been measured as a function of temperature in Sidoped GaAs single crystals subjected to various heat
treatments. Defects produced by these heat treatments trap positrons. In all the GaAs samples containing defects positron
lifetime was found to decrease with temperature in the range from 375 K to 16 K. The decrease is explained as due to the decrease
in the trapping rate. The trapping rate is mainly controlled by the diffusion of the positron to the trap. The diffusion constant
is determined mainly by the scattering from charged Si impurities. 相似文献
93.
94.
D. Bharathi Mohan K. Sreejith C.S. Sunandana 《Applied physics. B, Lasers and optics》2007,89(1):59-63
Silver thin films in the thickness range 2–10 nm produced by thermal evaporation onto glass substrates were systematically
iodized and carefully characterized by X-ray diffraction, atomic force microscopy (AFM) and optical absorption spectroscopy.
While the uniodized films are X-ray amorphous in keeping with their quasi-continuous nature and 2D islanded structure, briefly
iodized films showed characteristic beta AgI structure. Most interestingly, AFM of Ag films revealed uniform triangle-shaped
embryos whose shape does not change appreciably upon iodization. Optical absorption spectra of uniodized Ag films show intense
surface plasmon resonance (SPR) features with maxima at 440, 484 and 498 nm for the films of thicknesses 2, 5 and 10 nm, respectively,
with 5 nm films showing properties characteristic of optimally matched dielectric and electronic properties of the substrate
and sample, respectively. Finally, an interesting and unique SPR–exciton phase transition is observed as the ultra-thin films
are progressively iodized. These Ag and AgI films could be promising candidates for plasmonic and nanophotonic applications.
PACS 78.66.-w; 73.20.Mf; 71.35.Cc; 42.70; 68.37.Ps; 42.82.-m 相似文献
95.
D.Bharathi Mohan 《Journal of Physics and Chemistry of Solids》2004,65(10):1669-1677
Nanoscale crystallites of Ag-rich (Ag1−xCuxI, x=0.05, 0.10, 0.15 and 0.25), Cu-rich (Cu1-yAgyI, y=0.05, 0.10, 0.15 and 0.25) and intermediate Ag1-xCuxI (x=0.50) solid solutions and end members AgI, CuI with sizes in the range of 46-13 nm were synthesized by attrition at ambient temperature in a soft mechanochemical reaction (MCR) of Ag, Cu and I. Monophasic γ-AgI (zincblende, ) with disordered Ag+ sublattice and the crystallite size of about ∼31 nm was realized in the case of Ag0.75Cu0.25I (x=0.25) composition. Lattice parameter decreases linearly from 649 to 604 pm with increasing Cu concentration in the AgI-CuI system validating Vegard's law. Smallest size (∼13 nm) agglomerated nanocrystals were realized in the Cu-rich composition Cu0.75Ag0.25I (), while unagglomerated uniform-sized (∼17 nm) and spherical shape nanocrystallites of Ag0.50Cu0.50I () with maximum strain were synthesized for sensor applications using MCR. Differential scanning calorimetry study shows the systematic changes in the phase transition temperature with Cu substitution. Ag-rich composition posses less enthalpy (ΔH (x or Cu=0.05, 0.10, 0.15, 0.25)=6.0, 6.11, 6.6, 6.3 in kJ/mol) and entropy (ΔS (y or Ag=0.05, 0.10, 0.15, 0.25)=14.15, 14.1, 15.03, 13.6 in J/mol K) when compared to undoped AgI () implying greater thermal stability of γ-phase due to Cu-strengthened Ag-I bond. Enhanced entropy () in Cu0.75Ag0.25I (Cu-rich) solid solutions relative to CuI () indicates Ag-induced cation disorder. Fifteen percent Ag-doped CuI (Cu0.85Ag0.15I) nanocrystals apparently behave like microscopic p-n junctions with currents in the range of 10−6-10−8 A characterized by a non-linear I-V curve. 相似文献
96.
Indira S. Vinoth G. Bharathi M. Ramachandran R. Shanmuga Bharathi K. 《Research on Chemical Intermediates》2021,47(7):3051-3065
Research on Chemical Intermediates - A new class of mixed ligand complexes, [M(L)(phen)2], using a bidentate bischlorophenol ligand H2L (2,2′-methylenebis(4-chlorophenol)) and phenanthroline... 相似文献
97.
A. Zhu P. Bharathi H. G. Drickamer J. S. Moore 《Journal of polymer science. Part A, Polymer chemistry》2001,39(16):2859-2865
The effect of pressure up to 60 kbar was measured on the luminescence peak location and efficiency for a series of methoxy phenylacetylene dendrimers (MeO). Dendrimers MeO‐3, MeO‐7, MeO‐15, MeO‐31, MeO‐63, and MeO‐127 were studied as neat polymers. MeO‐3, MeO‐15, MeO‐63, and MeO‐127 were also investigated in dilute solutions in poly(tert‐butyl methacrylate). According to measurements of the dilute solutions, there is a charge‐transfer (CT) state that, for the smaller dendrimers, lies well above the π* state; for the larger dendrimers, it is the emitting state at 1 atm. With increasing pressure, the intramolecular CT state is rapidly stabilized, so that at high pressure the emission is from this state for all dendrimers. For the neat polymers, there is an initial redshift that reverses direction at a pressure that is higher for smaller dendrimers. This reversal is attributed to intermolecular CT. There may be changes in the molecular geometry and/or relative orientation of adjacent dendrimers that tend to stabilize the intermolecular CT in the solid state. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2859–2865, 2001 相似文献
98.
S. Sreedaran K. Shanmuga Bharathi A. Kalilur Rahiman L. Jagadish V. Kaviyarasan V. Narayanan 《Journal of inclusion phenomena and macrocyclic chemistry》2010,66(3-4):297-306
Trinuclear copper(II) and nickel(II) complexes have been prepared by using Schiff base ligands derived from 1,8-[bis(3-formyl-2-hydroxy-5-methyl) benzyl]-4,11-dimethyl-l,4,8,11-tetraazacyclotetradecane, and 1,8-[bis(3-formyl-2-hydroxy-5-bromo)benzyl]-4,11-dimethyl-l,4,8,11-tetraazacyclotetradecane with aliphatic and aromatic diamines. All the complexes were characterized by elemental and spectroscopic analysis. Electrochemical studies of the copper(II) complexes in DMF solution show three irreversible one electron reduction process around E pc 1 = ?0.59 to ?0.80 V, E pc 2 = ?0.89 to ?1.14 V and E pc 3 = ?1.17 to ?1.29 V, and for nickel(II) complexes it is around E pc 1 = ?0.63 to ?0.77 V, E pc 2 = ?1.20 to ?1.35 V and E pc 3 = ?1.60 to ?1.74 V. ESR spectra and magnetic moments of the trinuclear Cu(II) complexes show the presence of antiferromagnetic coupling. Cryomagnetic investigation of the trinuclear copper(II) complexes show that the observed ?2J values are in the range of 116–178 cm?1. The rate constants for hydrolysis of 4-nitrophenylphosphate by the complexes are in the range of 2.68 × 10?2 to 9.81 × 10?2 min?1. The rate constants values for the catecholase activity of the copper(II) complexes fall in the range of 3.03 × 10?2 to 9.32 × 10?2 min?1. All the complexes. 相似文献
99.
Hotha KK Vijaya Bharathi D Jagadeesh B Ravindranath LK Jaya Veera KN Venkateswarulu V 《Biomedical chromatography : BMC》2012,26(2):225-231
A highly reproducible, specific and cost-effective LC-MS/MS method was developed for simultaneous estimation of eszopiclone (ESZ) with 50 μL of human plasma using paroxetine as an internal standard (IS). The API-4000 LC-MS/MS was operated under the multiple reaction-monitoring mode using the electrospray ionization technique. A simple liquid-liquid extraction process was used to extract ESZ and IS from human plasma. The total run time was 1.5 min and the elution of ESZ and IS occurred at 0.90 min; this was achieved with a mobile phase consisting of 0.1% formic acid-methanol (15:85, v/v) at a flow rate of 0.50 mL/min on a Discover C(18) (50 × 4.6 mm, 5 μm) column. The developed method was validated in human plasma with a lower limit of quantitation of 0.1 ng/mL for ESZ. A linear response function was established for the range of concentrations 0.10-120 ng/mL (r > 0.998) for ESZ. The intra- and inter-day precision values for ESZ were acceptable as per FDA guidelines. Eszopiclone was stable in the battery of stability studies, viz. bench-top, autosampler and freeze-thaw cycles. The developed assay method was applied to an oral bioequivalence study in humans. 相似文献
100.
Hotha KK Vijaya Bharathi D Jagadeesh B Ravindranath LK Jaya Veera KN Venkateswarulu V 《Biomedical chromatography : BMC》2012,26(2):192-198
A highly sensitive, specific and simple LC-MS/MS method was developed for the simultaneous estimation of dexlansoprazole (DEX) with 50 μL of human plasma using omeprazole as an internal standard (IS). The API-4000 LC-MS/MS was operated under multiple reaction-monitoring mode using electrospray ionization. A simple liquid-liquid extraction process was used to extract DEX and IS from human plasma. The total run time was 2.00 min and the elution of DEX and IS occurred at 1.20 min. This was achieved with a mobile phase consisting of 0.2% ammonia-acetonitrile (20:80, v/v) at a flow rate of 0.50 mL/min on an X-terra RP 18 (50 × 4.6 mm, 5 μm) column. The developed method was validated in human plasma with a lower limit of quantitation of 2 ng/mL for DEX. A linear response function was established for the range of concentrations 2.00-2500.0 ng/mL (r > 0.998) for DEX. The intra- and inter-day precision values for DEX met the acceptance criteria as per FDA guidelines. DEX was stable in the battery of stability studies, viz. bench-top, auto-sampler and freeze-thaw cycles. The developed assay method was applied to an oral bioequivalence study in humans. 相似文献