Showing papers by "Joydeep Dutta published in 1998"
TL;DR: In this article, the optical extinction spectra of monodispersed particles is simulated using Mie scattering theory, and can be used as an in situ diagnostic tool for following the growth of particles during precipitation reactions.
Abstract: Transmission spectra of monodispersed particles exhibit pronounced resonance features from which particle properties can be deduced. ZnS powders were used as model materials since they can be synthesized by homogeneous precipitation with a narrow size distribution. The optical extinction spectra can be simulated using Mie scattering theory, and can be used as an in situ diagnostic tool for following the growth of particles during precipitation reactions. Using results of particle diameter measurements by other methods, information on the refractive index of the particles can be retrieved, indicating a highly porous internal structure of the spheres. Distinct features in the experimental and simulated spectra have been interpreted as to arise from circumference and diameter resonance effects in the particles. The simultaneous observation of these two effects allows one to estimate size and solid volume fraction from simple transmission spectra by application of an effective-medium model for the simulation parameters. The potential of application of Mie resonance effects for selective light screening or as pigments are discussed.
90 citations
TL;DR: In this paper, the micellar structure of PAA-g-PS in toluene has been demonstrated by dynamic light scattering and transmission electron microscopy (TEM).
Abstract: An amphiphilic poly(acrylic acid)/polystyrene graft copolymer (PAA-g-PS) has been used to form “nanoreactors” for the synthesis of gold clusters. Such copolymers tend to form stable micelles in non-polar organic solvents where the poly(acrylic acid) chains constitute the core, and the polystyrene chains, the shell. In the present study, the micellar structure of PAA-g-PS in toluene has been demonstrated by dynamic light scattering and transmission electron microscopy (TEM). The subsequent preparation of gold-graft copolymer composites involved the introduction of gold chloride (AuCl3), either in powder form or previously dissolved in ether, into the micellar cores of the PAA-g-PS in toluene. The gold salt was then reduced by ultraviolet (UV) irradiation of the emulsion, or of dried cast films. TEM and ultraviolet-visible (UV/Vis) spectroscopy were used to characterize the resulting composites. Gold particles of less than 5 nm in diameter were observed in all cases, but the size distribution and the spatial arrangement of the clusters in the cast films were modified when diethyl ether was used to introduce AuCl3 into the PAA-g-PS micellar cores. This was thought to be due to enhanced nucleation of the gold particles and partial disruption of the micellar cores in the presence of diethyl ether.
78 citations
TL;DR: In this paper, during the synthesis of ZnS powders by wet chemical precipitation, the formation of nanoporous spheres was observed, and the powders were investigated using thermogravimetric analysis, X-ray diffra...
Abstract: During the synthesis of ZnS powders by wet chemical precipitation, the formation of nanoporous spheres is observed. The powders have been investigated using thermogravimetric analysis, X-ray diffra ...
35 citations
TL;DR: This paper explored various gas phase processes for the fabrication of nanometersized Si and SiOx particles and measured their structural properties (agglomeration, size, shape, crystallinity, surface...
Abstract: We have explored various gas phase processes for the fabrication of nanometersized Si and SiOx particles and measured their structural properties (agglomeration, size, shape, crystallinity, surface ...
24 citations
01 Jan 1998
TL;DR: Reference LTP-CONF-1998-005View record in Web of Science Record created on 2005-01-12, modified on 2017-05-10 as discussed by the authors, created on 2011
Abstract: Reference LTP-CONF-1998-005View record in Web of Science Record created on 2005-01-12, modified on 2017-05-10
7 citations
TL;DR: In this article, the authors present a Web of Science Record created on 2005-01-12, modified on 2017-05-10, with the purpose of improving the quality of the Web.
Abstract: Reference LTP-ARTICLE-1998-025doi:101023/A:1006658415927View record in Web of Science Record created on 2005-01-12, modified on 2017-05-10
5 citations
01 Jan 1998
TL;DR: In this article, the synthesis of gold clusters on the surface of oxide fin is discussed, with a view to extending these synthetic processes to other noble metals such as gold and platinum.
Abstract: We have studied precipitation of noble metals with a view to extending these synthetic processes to other metals. In this paper we discuss the synthesis of gold clusters on the surface of oxide fin ...