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61.
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Zinc micro and nanostructures were synthesized in vacuum by condensing evaporated zinc on Si substrate at different gas pressures. The morphology of the grown Zn structures was found to be dependent on the oxygen partial pressure. Depending on oxygen partial pressure it varied from two-dimensional microdisks to one-dimensional nanowire. The morphology and structural properties of the grown micro and nanostructures were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Transmission electron microscopy (TEM) studies on the grown Zn nanowires have shown that they exhibit core/shell-like structures, where a thin ZnO layer forms the shell. A possible growth mechanism behind the formation of different micro and nanostructures has been proposed. In addition, we have synthesized ZnO nanocanal-like structures by annealing Zn nanowires in vacuum at 350 °C for 30 min. 相似文献
63.
Mandal AK Suresh M Das P Das A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(13):3906-3917
Herein, we report the host-guest-type complex formation between the host molecules cucurbit[7]uril (CB[7]), β-cyclodextrin (β-CD), and dibenzo[24]crown-8 ether (DB24C8) and a newly synthesized triphenylamine (TPA) derivative 1X(3) as the guest component. The host-guest complex formation was studied in detail by using (1)H?NMR, 2D NOESY, UV/Vis fluorescence, and time-resolved emission spectroscopy. The chloride salt of the TPA derivative was used for recognition studies with CB[7] and β-CD in an aqueous medium. The restricted internal rotation of the guest molecule on complex formation with either of these two host molecules was reflected in the enhancement of the emission quantum yield and the average excited-state lifetime for the triphenylamine-based excited states. Studies with DB24C8 as the host molecule were performed in dichloromethane, a medium that maximizes the noncovalent interaction between the host and guest fragments. The F?rster resonance energy transfer (FRET) process involving DB24C8 and 1(PF(6))(3), as the donor and acceptor fragments, respectively, was established by electrochemical, steady-state emission, and time-correlated single-photon counting studies. 相似文献
64.
D. Umamaheswari B.C. Jamalaiah T. Sasikala Il-Gon Kim L. Rama Moorthy 《Journal of Non》2012,358(4):782-787
The photoluminescence properties of different concentrations of Sm3+ ions doped sodium fluoroborate (SFB) glasses of composition Na2O–LaF3–CaF2–AlF3–B2O3–SmF3 have been investigated. The energy level analysis is carried out using free-ion Hamiltonian model. The Judd–Ofelt intensity parameters are used to evaluate the laser characteristic parameters such as spontaneous transition probability, radiative lifetime and fluorescence branching ratio for 4G5/2 → 6HJ (J = 5/2, 7/2, 9/2 and 11/2) emission transitions of Sm3+ ion. The principal photoluminescence transitions of interest are identified by recording the emission spectra for different Sm3+ ion concentrations and measuring their emission cross-sections, integrated absorption cross-sections and optical gain parameters. The decay profiles from the 4G7/2 excited manifold state to its lower lying energy levels have been recorded by monitoring the excitation and emission wavelengths at 402 and 600 nm, respectively. The dependence of effective fluorescence lifetime on the Sm3+ concentration is also discussed. 相似文献
65.
Keshaba Nanda ParidaSamik Jhulki Susovan MandalJarugu Narasimha Moorthy 《Tetrahedron》2012,68(47):9763-9768
Oxidation of benzyl alcohols, benzyl halides, and alkylbenzenes to their corresponding oxidation products has been shown to be accomplished directly with oxone. The methodology that involves mere stirring/heating of the reactants and oxone in acetonitrile/water (1:1, v/v) is simple and practical, but is limited to substrates that do not contain sensitive functionalities and heteroaromatic rings. 相似文献
66.
J.S. Yadav Sandip Sengupta Nagendra Nath Yadav D. Narasimha Chary Ahmad Alkhazim Al Ghamdi 《Tetrahedron letters》2012,53(44):5952-5954
(−)-Lardolure and (2R,4R,6R,8R)-2,4,6,8-tetramethylundecanoic acid have been synthesized via lipase catalyzed desymmetrization strategy to create two methyl chiral centers. Other key steps involved in the synthesis are Wittig reaction, Evan’s asymmetric alkylation, Grignard reaction, Pd-catalyzed isomerization of primary allylic alcohol to corresponding saturated aldehyde, and PhNO/proline catalyzed MacMillan α-hydroxylation. 相似文献
67.
Somepalli Venkateswarlu Meka Satyanarayana Gandrothu Narasimha Murthy Vidavalur Siddaiah 《Tetrahedron letters》2012,53(21):2643-2646
Cyclisation of 2-(2-aminophenyl)quinazolin-4(3H)-ones on to N3 and on to N1 leading to 6-alkyl-(8H)-quinazolino[4,3-b]quinazolin-8-one and 6-alkyl-(13H)-quinazolino[3,4-a]quinazolin-13-one, respectively was described for the first time. The differences in the IR and carbon NMR data of these isomeric fused quinazolinoquinazolinones afford a useful method for distinguishing between the two series. 相似文献
68.
M. V. Moorthy 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1995,46(5):793-806
In this paper an algorithm to numerically invert two-dimensional Laplace transform known in closed form as an analytic function is presented. The method is based on expanding the inverse function in a series of products of (generalized) Laguerre polynomials. It is based on the method by Weeks (1966) and the generalized version presented by Piessens and Branders (1971) for the one-dimensional case. 相似文献
69.
70.