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111.
M. Bangal S. Ashtaputre S. Marathe A. Ethiraj N. Hebalkar S. W. Gosavi J. Urban S. K. Kulkarni 《Hyperfine Interactions》2005,160(1-4):81-94
Semiconductor nanoparticles exhibit size dependent properties, when their size is comparable to the size of Bohr diameter
for exciton. This can be exploited to increase fluorescence efficiency or increase the internal magnetic field strength in
doped semiconductors. Nanoparticles are usually unstable and can aggregate. It is therefore necessary to protect them. Surface
passivation using capping molecules or by making core–shell particles are some useful ways. Here synthesis and results on
doped and un-doped nanoparticles of ZnS, CdS and ZnO will be discussed. We shall present results on core–shell particles using
some of these nanoparticles and also discuss briefly the effect of Mn doping on hyperfine interactions in case of CdS nanoparticles. 相似文献
112.
113.
U.D. Kulkarni 《Progress in Crystal Growth and Characterization of Materials》1997,34(1-4):165-173
Attention is focussed on the fact that the β—Mn, the σ—phase and the Al5Ti3 and the Al11Ti7 superlattice derivatives of the δ—AlTi phase all belong to a category of structures which comprises an identical periodic arrangement of square and rhombic tiles — the shapes of the rhombic tiles being different in each of these cases. While the first and the second structures constitute periodic approximants of the octagonal and the dodecagonal quasicrystals respectively, the last two (superlattice) structures are the approximants of a hypothetical quasiperiodic superlattice structure. The strip projection method has been used here to model the intermediate structures which arise during the continuous periodic to quasiperiodic transitions between the relevant structures and was found to be quite successful in explaining many of the related experimental findings. 相似文献
114.
A. Gulyani R. Srinivasa Gopalan G. U. Kulkarni S. Bhattacharya 《Journal of Molecular Structure》2002,616(1-3)
9-Anthryl and 1-pyrenyl terpyridines (1 and 2, respectively), key precursors for the design of novel fluorescent sensors have been synthesized and characterized by 1H NMR, mass spectroscopy and X-ray crystallography. Twisted molecular conformations for each 1 and 2 were observed in their single crystal structures. Energy minimization calculations for the 1 and 2 using the semi-empirical AM1 method show that the ‘twisted’ conformation is intrinsic to these systems. We observe interconnected networks of edge-to-face CHπ interactions, which appear to be cooperative in nature, in each of the crystal structures. The two twisted molecules, although having differently shaped polyaromatic hydrocarbon substituents, show similar patterns of edge-to-face CHπ interactions.The presently described systems comprise of two aromatic surfaces that are almost orthogonal to each other. This twisted or orthogonal nature of the molecules leads to the formation of interesting multi-directional ladder like supramolecular organizations. A combination of edge-to-face and face-to-face packing modes helps to stabilize these motifs. The ladder like architecture in 1 is helical in nature. 相似文献
115.
116.
A. K. Jain V. N. Kulkarni D. K. Sood 《Applied Physics A: Materials Science & Processing》1981,25(2):127-133
We present a scheme for solution of the heat flow equation in one-dimension incorporating melting and vapourization produced
under pulsed laser irradiation. The method can be applied to pure materials as well as multilayered structures such as deposited
films. The variation of physical properties with temperature can be easily taken into account. Results of calculation are
presented for aluminium and for chromium and antimony layers deposited on aluminium. As a consequence of excessive vapourization
at high energy densities, the melt depth and the melt duration do not increase beyond a certain limit. The resolidification
front velocity is strongly dependent on energy density and can be controlled in an experiment by a careful choice of laser
parameters. Some recent experimental data on laser treated chromium films are discussed in light of our calculations. 相似文献
117.
The magnetic properties of the spinel series GexCu1?xFe2O4 (X = 0 to 0.8) have been investigated by means of Mössbauer spectroscopy. Mössbauer spectra for X = 0.0 to 0.6 suggest the existence of two hyperfine fields, one due to the Fe3+ tetrahedral ions (A-sites) and the other due to Fe3+ octahedral ions (B-sites), while for X = 0.8 it shows the superposition of hyperfine field split spectra from A- and B-site ions and a broad central line spectrum. For 0.2 ? X ? 0.4, fast electron exchange among octahedral iron ions occurs as in Fe3O4. The variations of nuclear magnetic fields at the A- and B-sites are explained on the basis of AB and BB supertransferred hyperfine interactions. 相似文献
118.
Starting from 2-cyclopentenone the title compound has been synthesized via a combination of [2+2] and [4+2] cycloaddition reactions. 相似文献
119.
Surface composition and depth profile of native oxide on Fe67Co18B14Si1 metallic glass has been investigated using Auger electron spectroscopy. The native oxide is compared with chemisorbed oxygen on the cleaned surface. Results indicate that boron segregates on the surface in the presence of oxygen. The low energy L23M45M45 peak of iron in metallic glass is compared with that in crystallized sample and pure iron foil. 相似文献
120.
R.K. Dhumwad A.B. Patwardhan V.T. Kulkarni M.I. Savadatti 《Journal of Molecular Spectroscopy》1981,85(1):177-188
Employing the various isotopes of carbon, (0-0) bands of the C2 Swann system have been investigated. Comparisons have been made between the observed rotational line positions and those obtained by computer calculations with the respective constants evaluated from 12C2. There is a good agreement (within ± 0.5 cm?1 in most of the cases) between the two sets of values. The studies include the effect of change of nuclear mass and spin on different aspects of rotational structure and intensity pattern. 相似文献