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排序方式: 共有103条查询结果,搜索用时 15 毫秒
41.
Synthesis and optical properties of CdS nanoribbons 总被引:1,自引:0,他引:1
Kar S Satpati B Satyam PV Chaudhuri S 《The journal of physical chemistry. B》2005,109(41):19134-19138
Rapid production of single crystalline CdS nanoribbons with hexagonal wurtzite phase has been achieved by thermal evaporation of CdS powder on Si wafers. The flow rate of the carrier (Ar) gas along with the synthesis temperature plays an important role in defining the size and shape of the CdS nanoribbons. Scanning electron and transmission electron microscopic observations revealed the nanoribbons to have a flat end as well as side surfaces which will make it ideal for optoelectronic devices such as nanolasers and light emitting diodes based on individual nanoribbons. The nanoribbons have widths within 200-400 nm and lengths approximately a few hundred micrometers. Room-temperature photoluminescence measurements show green emission centered at approximately 525 nm which may be ascribed to the near band edge emission. The Raman spectra of the CdS nanoribbons show peaks around 304, 609, 915, and 1220 cm(-1) corresponding to the first-, second-, third-, and fourth-order longitudinal optical phonon modes, respectively. 相似文献
42.
Bhaskar Soman Swapna Challagulla Soumitra Payra Srikanta Dinda Sounak Roy 《Research on Chemical Intermediates》2018,44(4):2261-2273
The main aim of this work is to discriminate the closely related adsorption and catalytic degradation processes that occur during a photocatalytic reaction. Very high-surface-area TiO2 and Pd-doped TiO2 were synthesized by microwave-assisted hydrothermal synthesis and used for degradation of methylene blue as a model pollutant dye. Thorough structural, morphological, and surface analyses of the synthesized catalysts were conducted to investigate key material properties that influence adsorption and catalytic performance. The adsorption capacity of the catalysts was determined by fitting adsorption data using the Langmuir isotherm model, and the photocatalytic activity of the synthesized samples was evaluated by periodically measuring the concentration of methylene blue as it was photocatalytically degraded under ultraviolet (UV) light. The results indicated that noble-metal incorporation compromised adsorption but favored catalytic performance. 相似文献
43.
Mala Anchal Srivastava Akhilesh K. Pandey Om P. Sengupta Soumitra K. 《Transition Metal Chemistry》2000,25(6):613-616
Bis(cyclopentadienyl)titanium(IV) and zirconium(IV) chlorides react with bis(hydrazones) derived from 1,1-diacetylferrocene in anhydrous THF in the presence of base to give complexes of the type [(Cp2MCl)2L] [M = Ti or Zr; LH2 = ferrocenyl bis(hydrazones)]. Tentative structures are proposed for these complexes based upon elemental analyses, electrical conductance, magnetic moment and spectroscopic data. 相似文献
44.
The reactions of bis(cyclopentadienyl)titanium(IV) chloride with a new class of bis(thiosemicarbazones) (H2L), derived by condensing isatin with different N(4)‐substituted thiosemicarbazides, have been studied both by a conventional stirring method and also using microwave technology. Binuclear products of type [{(η5‐C5H5)2TiCl} 2(L)] have been isolated in both cases. Tentative structural conclusions are drawn for the reaction products based upon analysis, electrical conductance, magnetic moment and spectral (UV‐visible, IR, 1H NMR and 13C NMR) data. FAB mass spectra of these compounds were also recorded to confirm the binuclear structures. Studies were conducted to assess the growth inhibiting potential of the ligands and complexes against various fungal, viral and bacterial strains. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
45.
Kishalay Bhar Sumitra Das Smita Satapathi Partha Mitra Joan Ribas Barindra Kumar Ghosh 《Polyhedron》2010
Two neutral nickel(II) coordination polymers [Ni(en)(dca)2]n (1) and [Ni(dmen)(dca)2]n (2) (en = ethylenediamine; dmen = N,N-dimethylethylenediamine; dca = dicyanamide) have been synthesized and X-ray crystallographically characterized. Each nickel(II) center in 1/2 adopts a distorted octahedral coordination environment with a NiN6 chromophore ligated by two amine N atoms of the bidentate amine (en/dmen) and four nitrile N atoms of μ1,5 bridged dca. The metal(II) centers are connected with each other through single μ1,5 M–NCNCN–M bridges, resulting in a 2D layer structure with a (4,4) topology in 1 and a 3D network of topology (6,6) in 2. Multiple lateral N–H···N and C–H···N hydrogen bondings promote dimensionality. The magnetic susceptibility results of 1 and 2 at very low temperature support the zero-field splitting effect of the nickel(II) ions. 相似文献
46.
Shape selective growth of CdS one-dimensional nanostructures by a thermal evaporation process 总被引:1,自引:0,他引:1
CdS one-dimensional nanoforms such as nanowires, nanoribbons, network-like nanowires, pearl necklace type nanowires, helical-like nanowires, and nanowire arrays were formed on Si substrates by a simple thermal evaporation route. The shapes of the one-dimensional CdS nanoforms were controlled by varying the experimental parameters such as temperature and position of the substrates. Formation of the CdS one-dimensional nanoforms was initiated by the Au catalyzed vapor-liquid-solid technique, whereas the vapor-solid process played a crucial role in defining the shapes of the nanoforms. Different optical characterizations such as optical absorbance, photoluminescence, and Raman spectroscopy were adopted to explore the physical and structural quality of these CdS nanoforms. 相似文献
47.
Simple solvothermal route to synthesize ZnO nanosheets, nanonails, and well-aligned nanorod arrays 总被引:5,自引:0,他引:5
ZnO nanosheets, nanonails, and well-aligned nanorods were fabricated on Zn foils by a solvothermal approach using ethanol as the solvent. A lower synthesis temperature and a shorter time period favor the formation of nanosheets. By optimizing the synthesis temperature and time period, ZnO nanonails with a hexagonal cap and a long stem could be produced. A higher temperature was not favorable to produce uniform and smooth nanorods. Well-aligned ZnO nanorod arrays were produced with diameters within 100-250 nm and lengths up to approximately 6 microm when NaOH was added to the solvent. By optimizing the reaction parameters, the morphology, size, and orientation of the nanoforms could be tailored. The ZnO nanorods exhibit an excitonic strong UV emission and a defect-related broad green emission at room temperature. The defect-related green emission band decreased with the improvement of the degree of alignment of the nanorods. 相似文献
48.
Palladium‐Catalyzed Annulation of Diarylamines with Olefins through CH Activation: Direct Access to N‐Arylindoles 下载免费PDF全文
Dr. Upendra Sharma Dr. Rajesh Kancherla Togati Naveen Soumitra Agasti Prof. Debabrata Maiti 《Angewandte Chemie (International ed. in English)》2014,53(44):11895-11899
A palladium‐catalyzed dehydrogenative coupling between diarylamines and olefins has been discovered for the synthesis of substituted indoles. This intermolecular annulation approach incorporates readily available olefins for the first time and obviates the need of any additional directing group. An ortho palladation, olefin coordination, and β‐migratory insertion sequence has been proposed for the generation of olefinated intermediate, which is found to produce the expected indole moiety. 相似文献
49.
Soumitra Satapathi Fadong Yan Robinson Anandakathir Ke Yang Lian Li Ravi Mosurkal 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(12):1180-1183
Photovoltaic performance of dye sensitized solar cells fabricated with a commercially available thiophene based copolymer was investigated. Poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(bithiophene)], a highly soluble polythiophene, was used as a sensitizer. An open-circuit voltage of 0.64 V and a short-circuit current density of 0.36 mA/cm2 were measured. The incident photon to current conversion efficiency for the polymer was measured. Fluorescence from the other polythiophene, poly(3,3′-didodecyl quarter thiophene) was found to be quenched when blended with phenyl C61 butyric acid methyl ester (PCBM) (1:1 wt ratio), indicating the charge transfer from the conjugated polymer to PCBM. 相似文献
50.
Soumitra Choudhary Joseph C. White Whitney L. Stoppel Susan C. Roberts Surita R. Bhatia 《Rheologica Acta》2011,50(1):39-52
We report the preparation and rheological characterization of interpenetrating polymer network (IPN) hydrogels made from alginate
and hydrophobically modified ethyl hydroxyl ethyl cellulose (HMEHEC). To our knowledge, there have been no studies of the
gelation behavior of IPNs. We found that the rheology of these systems can be easily tuned, with the elastic modulus of the
IPN strongly dependent on the relative ratio of HMEHEC to alginate. The sol–gel transition of these systems was found to satisfy
the Winter–Chambon criterion for gelation at various crosslinker densities. From the power law relationship of the dynamic
moduli (G
′ ~G
″ ~ω
n), the exponent n appears to be dependent on both the crosslinker density and relative amount of two polymers. The value of n was found to be ~0.5 for all samples for stoichiometric amounts of crosslinker. The effect of molecular weight of HMEHEC
on the gel point and viscoelastic exponent has also been reported. Alginate seems to dominate the kinetics of the process
but the effect of high molecular weight HMEHEC on the gel point, especially at lower proportion was also evident. 相似文献