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991.
992.
Alagappan A Costen ML McKendrick KG 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,63(5):910-922
We describe the application of frequency modulated spectroscopy (FMS) with an external cavity tuneable diode laser to the study of the scalar and vector properties of inelastic collisions. CN X(2)Sigma(+) radicals are produced by polarized photodissociation of ICN at 266 nm, with a sharp velocity and rotational angular momentum distribution. The collisional evolution of the distribution is observed via sub-Doppler FMS on the A(2)Pi-X(2)Sigma(+) (2,0) band. He, Ar, N(2), O(2) and CO(2) were studied as collider gases. Doppler profiles were acquired in different experimental geometries of photolysis and probe laser propagation and polarization, and on different spectroscopic branches. These were combined to give composite Doppler profiles from which the speed distributions and specific speed-dependent vector correlations could be determined. The angular scattering dynamics with species other than He are found to be very similar, dominated by backward scattering which accompanies transfer of energy between rotation and translation. The kinematics of collisions with He are not conducive to the determination of differential scattering and angular momentum polarization correlations. Angular momentum correlations show interesting differences between reactive and non-reactive colliders. We propose that this reflects differences in the potential energy surfaces, in particular, the nature and depth of attractive potential wells. 相似文献
993.
994.
Yunfan Zou 《Tetrahedron letters》2010,51(9):1336-1337
The terminal dienyne of (9Z)-9,13-tetradecadien-11-ynal, the sex pheromone of the avocado seed moth, Stenoma catenifer, was constructed by coupling a vinyl iodide precursor with commercially available 1-buten-3-yne with Pd catalysis, resulting in a short and efficient synthesis of the pheromone. 相似文献
995.
996.
<正>Polypyrrole/polyvinylalcohol(PPy/PVA) foam was prepared by direct foam polymerization in water and then it was coated on the indium-tin oxide transparent conductive glass(ITO) to form conventional three-electrode cell.FTIR and UV-vis spectra were adopted to characterize the molecular structure and the absorption spectra of foam material,respectively.The porous structure of PPy/PVA foams and their photoelectric conversion behaviors were studied.The dimension of the pores is bigger than 100μm in diameter.Compared with the smooth film,the V_(oc) and I_(sc) of the foam film enhanced by 1.58-fold and 5.59-fold,respectively. 相似文献
997.
WESTON THATCHER BORDEN 《Molecular physics》2013,111(3):337-347
This paper describes a collaboration between Professor Ernest Davidson and the author, which began in 1976 and lasted until Ernest left the University of Washington in 1984. During those 9 years we co-authored a total of 34 papers that described the results of ab initio calculations on a variety of different types of organic molecules, These included anti-aromatic annulenes, carbanions, carbenes, conjugated radicals and radical cations, and non-Keklé hydrocarbon diradicals. Our collaboration led to insights about symmetry breaking, both real and artefactual, which formed the basis for a frequently-cited review article on this subject that we co-authored. However, our most often-referenced paper was concerned with predicting the sizes and signs of the singlet-triplet splittings in diradicals, based on whether or not the non-bonding Hückel molecular orbitals of a diradical can be chosen so that they are confined to disjoint sets of atoms. In 1984, we co-authored a paper on the Cope rearrangement. Since then, we have both continued to publish papers on this interesting reaction, but independently, rather than together. The results of the calculations that we each performed on the Cope rearrangement and how this reaction is affected by radical-stabilizing substituents are described. Our independent discoveries, that calculations beyond the CASSCF level are necessary in order to describe correctly the transition structure for the Cope rearrangement, led to our most recent joint publication, a 1996 review on the general importance of including dynamic correlation in ab initio calculations. 相似文献
998.
电偶极子位于均匀介质球中时球外电场的研究 总被引:1,自引:0,他引:1
采用分离变量法求解了电偶极子位于均匀介质球中时复连通域的拉普拉斯方程和泊松方程,求出了球内外两种不同介质的电势分布和球面上的极化电荷分布;通过求解二阶非线性微分方程得到了球外的电场线函数;利用计算软件Math-ematica 5.0,作出了相应的相互正交的等势线簇图形和电场线簇图形,并且进行了必要的讨论. 相似文献
999.
Geert Brocks 《Theoretical chemistry accounts》2000,104(2):116-122
Density functional calculations using pseudopotentials and a plane-wave basis set are applied to study the geometry and the
electronic structure of conjugated polymers consisting of heterocyclic aromatic rings. This article focuses on the computational
methods. The influence of the pseudopotentials on the structural and electronic properties is studied. The rates of convergence
of these properties with respect to the basis set size and the density of sampling points for the Brillouin zone integration
are considered. The effects of using different exchange–correlation potentials (local density or generalized gradient approximations)
are examined. It is shown that smooth norm-conserving pseudopotentials used for calculations on conjugated polymers lead to
converged results with a moderately sized basis set.
Received: 20 August 1999 / Accepted: 23 November 1999 / Published online: 19 April 2000 相似文献
1000.
Two basic types of dephasing mechanisms, carrier-carrier and carrier-phonon scattering including hole-hole and hole-phonon
scattering are proposed in the theory of ultrafast polarization dephasing of continuum transitions in bulk semiconductors.
The contribution of optical phonon scattering to the dephasing rate is the average of the scattering rates for electrons and
holes. A weighting factor that reflects the change in the momentum of the particle in a collision is introduced into the usual
integral of the carrier-carrier scattering rate to describe the contribution of carrier-carrier scattering to the dephasing
rate for the case of static screening interaction. The theoretical calculations are in quantitative agreement with the reported
experimental results. 相似文献