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Gaballah ST Hussein YH Anderson N Lian TT Netzel TL 《The journal of physical chemistry. A》2005,109(48):10832-10845
Femtosecond, picosecond, and nanosecond transient absorbance (TA) and picosecond emission kinetics results are presented for three 5-(1-pyrenyl)-2'-deoxyuridine nucleosides each with a different two-atom linker joining pyrenyl C-1 to uracil C-5. The linkers are respectively -NHCO-, -(CH(2))(2)-, and -C[triple bond]C- for PAdU, PEdU, and PYdU. For all three nucleoside conjugates, most conformers undergo intramolecular charge transfer (CT) from their pyrenyl (1)(pi,pi) excited states to form Py(*+)/dU(*-) CT products in ultrashort times: 相似文献
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An efficient method for calculating the Lagrange multipliers and the analytical gradients of one state included in a state average MCSCF wave function is presented. It is demonstrated that the state average energy of an ‘equal-weight’ scheme is invariant to rotations within the state average subspace and that the corresponding rotations should be eliminated from the Lagrangian equations. Finally, a diagnostic is presented, which gauges the energy difference between a state defined by a state average calculation and the corresponding fully variational multi-configurational SCF state. 相似文献
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ChemInform Abstract: X-Ray Structural Studies of the Polymorphic Elpasolites K2LiAlF6 and Rb2LiGaF6.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献
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The thin-film spinel-forming solid state reaction between Al2O3 and MgO has been studied under initially non-coherent conditions. MgO films in (001) orientation on
-cut sapphire single crystals were heated at 1100°C for 30 min or 1h. The film/substrate reaction proceeds via cation counterdiffusion as was revealed by a marker experiment. The MgAl2O4 films formed were predominantly (001) oriented, with an additional systematic tilt of about 5° of the spinel lattice around the [010] axis. The structure of the Al2O3
/MgAl2O4(001) and MgAl2O4(001)/MgO(001) reaction fronts has been investigated on cross section samples by high-resolution electron microscopy. It appeared that after starting from an incoherent interface, the Al2O3
/MgAl2O4(001) front assumes an almost fully coherent structure during the reaction. As a result the lattice misfit is reduced to 1%, and interfacial ledges are formed. The latter most probably play an active role in the necessary c.p.h. f.c.c. reconstruction of the oxygen sublattice. The MgAl2O4(001)/MgO(001) reaction front consists of coherent regions divided by misfit dislocations. During the reaction the former run ahead whereas the latter lag behind. As a result the morphology of the reaction front is bowed. The results confirm earlier observations of Carter and Schmalzried of the semicoherent Al2O3(00.1)/CoAl2O4(111) interface, thus strongly supporting the conclusion of a fundamental new phase transformation mechanism specific to oxide systems.Presented at the workshop on High-Voltage and High-Resolution Electron Microscopy, February 21–24, 1994, Stuttgart, Germany. 相似文献
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Studies of six 5-(pyren-1-yl-ethynyl)-2'-deoxyuridine (U(PY))-substituted DNA duplexes in this work test and support the conclusions reported by Gaballah et al. (J. Phys. Chem. B 2005, 109, 5927-5934) based on investigations of 5-(2-pyren-1-yl-ethylenyl)-2'-deoxyuridine (U(PE))-substituted DNA hairpins. As expected because of the rigid ethynyl linker in U(PY) (compared to the flexible ethylenyl linker in U(PE)), U(PY)-substituted duplexes do not show enhanced charge transfer (CT) emission quantum yields for duplexes with 5-fluorodeoxyuridine (U(F)) electron traps near U(PY) compared to duplexes without traps. Furthermore, the average CT lifetime and emission quantum yield of U(PY)-substituted duplexes is independent of the U(F) trap location. These new results strongly suggest that the excess electron in the PY*+/dU*- CT state of U(PY) is restrained from hopping to nearby U(F) traps due to attraction to PY*+. 相似文献
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RIVLIN T. J.; RUSCHEWEYH ST.; SHAFFER D.; WIRTHS K. J. 《IMA Journal of Numerical Analysis》1983,3(3):327-332
Given (1, 0), n N, we discuss the optimal recoveryof (), for analytic and bounded in < 1, from the knowledge of the values of at n points z1,.zm[0,l),where these points are chosen to produce the least possibleintrinsic error. The optimal algorithms are explicitly determined. 相似文献
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A FORTRAN computer program for automatic neutron activation analysis is presented. The program locates and identifies peaks
in a gamma-ray spectrum, calculates peak areas and the concentrations of the elements of interest in the sample. This program
was specifically designed for the SLOWPOKE reactor, it uses a semi-absolute method and does not need standards or flux monitors.
The program was written so as to minimize the computation time, and a typical 4096-channel spectrum is processed in five seconds
by an IBM 360/75 computer. 相似文献
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Thermal decomposition of zinc carbonate hydroxide 总被引:3,自引:0,他引:3
N. Kanari D. Mishra I. Gaballah B. Dupr Mineral Processing Environmental Engineering Team 《Thermochimica Acta》2004,410(1-2):93-100
This study is devoted to the thermal decomposition of two zinc carbonate hydroxide samples up to 400 °C. Thermogravimetric analysis (TGA), boat experiments and differential scanning calorimetry (DSC) measurements were used to follow the decomposition reactions. The initial samples and the solid decomposition products were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) and laser particle size analyzer. Results showed that zinc carbonate hydroxide decomposition started at about 150 °C and the rate of decomposition became significant at temperatures higher than 200 °C. The apparent activation energies (Ea) in the temperature range 150–240 °C for these two samples were 132 and 153 kJ/mol. The XRD analyses of the intermediately decomposed samples and the DSC results up to 400 °C suggested a single-step decomposition of zinc carbonate hydroxide to zinc oxide with not much change in their overall morphologies. 相似文献