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Electron Spectra (electron + spectrum)
Selected AbstractsSynthesis, characterization and biological properties of sulfonamide-derived compounds and their transition metal complexesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 8 2009Zahid H. Chohan Abstract Sulfonamide-derived compounds and their first row d-transition metal chelates [cobalt(II), copper(II), nickel(II) and zinc(II)] have been synthesized and characterized. The nature of bonding and structure of all the synthesized compounds have been proposed from magnetic susceptibility and conductivity measurements, IR, 1H and 13C NMR, electron spectra, mass spectrometry and CHN analysis data. The structure of ligand, 4-{[(E)-(5-chloro-2-hydroxyphenyl) methylidene] amino}- N -(4,6-dimethyl pyrimidin-2-yl) benzene sulfonamide has also been determined by X-ray diffraction method. An octahedral geometry has been suggested for all the complexes. The ligands and metal complexes have been screened for their in vitro antibacterial, antifungal and cytotoxic activity. The results of these studies revealed that all compounds showed moderate to significant antibacterial activity against one or more bacterial strains and good antifungal activity against various fungal strains. Copyright © 2009 John Wiley & Sons, Ltd. [source] Characterization of aluminum,organic-stabilized platinum,colloid networks with electron and photon spectroscopiesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 5 2003L. Beuermann Abstract We have measured and interpreted the ultraviolet (HeI) and X-ray photoelectron spectra and the metastable impact electron spectra (MIES) from aluminum,organic-stabilized platinum,colloids and colloid networks, deposited on silicon substrates and characterized by X-ray photoelectron spectroscopy, scanning Auger electron microscopy and transmission electron microscopy. MIES, in particular, gives information on the electronic structure of the spacer molecules interconnecting the colloids. In addition, changes in the electronic structure of the platinum clusters that are induced by different spacer molecules were identified by means of X-ray absorption near-edge structure measurements at the platinum LIII -edge of these materials. This combination of techniques was also employed to follow the chemical changes that occur upon heating of the network in situ. It turns out that the thermal decomposition of the network is driven by the disintegration of the spacer molecules. Moreover, less sintering of the colloidal particles occurs in the networked systems than in unconnected particles. Most of the networked platinum,particles are still present in their original shape even after the destruction of spacer molecules. This observation could be linked to the encapsulation of these platinum particles into an (AlO) protecting shell. Copyright © 2003 John Wiley & Sons, Ltd. [source] Calculated spectral properties of perylene orange, perylene red, and their complex with sodium azideINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 13 2007Anuar Aldongarov Abstract Using the method of density functional theory in approximating B3LYP with the basis set 6-31G(d) the computations of structures of the following dyes 2,2,- N - N,-di(1,3-diisopropylbenzene)-diimide 3,4,9,10-perylenetethracarbon acid (Perylene Orange-PO) and 1,6,7,12-tethraphenyl ether 2,2,- N,N,-di(1,3-diisopropylbenzene)-diimide 3,4,9,10-perylenetethracarbon acid (Perylene Red-PR) were performed. It was revealed that PO and PR have nonplanar structures. On the basis of the predicted geometrical structures and molecular orbitals of S0 ground state their theoretical UV-vis spectra, which are in good agreement with experiment, were obtained by applying time-dependent DFT (TDDFT) method. In addition, the calculations of complex [PR , NaN3] and its UV-vis spectrum, which was compared with the observed electron spectrum of PR ethanol solution in the presence of NaN3 under the laser irradiation at 532 nm, were carried out. By using DFT method at B3LYP level the calculations of the assumed complex were made where the reaction coordinate was the distance between Na+ and carbonyl group O atom. It was suggested that [PR , NaN3] complex formation involves transition of PR to the triplet state which brings about formation of PR anion. New peak at 793 nm in UV-vis spectrum of this solution under the laser irradiation at 532 nm is supposed to be a PR anion band. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 [source] Density functional study of graphene overlayers on SiCPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 7 2008Alexander Mattausch Abstract Despite the ongoing "graphene boom" of the last three years our understanding of epitaxial graphene grown on SiC substrate is only beginning to emerge. Along with experimental methods such as low energy electron diffraction (LEED), scanning tunneling microscopy (STM) and angle resolved photoemission spectroscopy (ARPES), ab initio calculations help to uncover the geometric and electronic structure of the graphene/SiC interface. In this chapter we describe the density-functional calculations we performed for single and double graphene layers on Si- and C-terminated 6H-SiC surfaces. Experimental data reveal a pronounced difference between the two surface terminations. On a Si-terminated surface the interface adopts a 6,3 × 6,3 unit cell whereas the C-face supports misoriented (turbostratic) graphene layers. It has been recently realized that, on the Si-face, the large commensurate cell is subdivided into patches of coherently matching to the substrate carbon atoms. In our calculations we assumed the "coherent match" geometry for the whole interface plane. This reduces the periodic unit to the ,3 × ,3R 30° cell but requires a substantial stretching of the graphene sheet. Although simplified, the model provides a qualitative picture of the bonding and of the interface electron energy spectrum. We find that the covalent bonding between the carbon layer and the substrate destroys the massless "relativistic" electron energy spectrum, the hallmark of a freestanding graphene. Hence the first carbon layer cannot be responsible for the graphene-type electron spectrum observed by ARPES and rather plays a role of a buffer between the substrate and the subsequent carbon sheets. The "true" graphene spectrum appears with the second carbon layer which exhibits a weak van der Waals bonding to the underlying structure. For Si-terminated substrate, we find that the Fermi level is pinned by the interface state at 0.45 eV above the graphene Dirac point, in agreement with experimental data. This renders the interface metallic. On the contrary, for a C-face the "coherent match" model predicts the Fermi level exactly at the Dirac point. However, this does not necessarily apply to the turbostratic graphene layers that normally grow on the C-terminated substrate. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||