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981.
The combination of valence band photoemission and inverse photoemission spectroscopy is applied to study the densities of occupied and unoccupied states of perylene derivative and phthalocyanine organic layers on inorganic semiconductors. The ionisation energies and electron affinities are determined and it is proposed that the transport gap of the materials can be evaluated from the distance of the HOMO and LUMO edges. The resulting values for the transport gap which are somewhat smaller than other published data are in good agreement with e.g. electrical measurements. The experimental spectra are compared with simulated ones obtained by density functional theory calculations. 相似文献
982.
B. T. Bilalov 《Siberian Mathematical Journal》2006,47(1):18-27
We consider power systems with complex-valued coeficients. We establish a necessary and suficient condition for completeness and minimality and also a necessary condition for the basis property of these systems in Lebesgue spaces. 相似文献
983.
Photonic band structures of two-dimensional photonic crystals with deformed lattices 总被引:2,自引:0,他引:2
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Using the plane-wave expansion method, we have calculated and analysed the
changes of photonic band structures arising from two kinds of deformed
lattices, including the stretching and shrinking of lattices. The square
lattice with square air holes and the triangular lattice with circular air
holes are both studied. Calculated results show that the change of lattice
size in some special ranges can enlarge the band gap, which depends strongly
on the filling factor of air holes in photonic crystals; and besides, the
asymmetric band edges will appear with the broken symmetry of lattices. 相似文献
984.
把具有宽完全带隙的粗锐复合的周期常数为a的二维正方格子再与周期常数为a2的大周期简单正方格子复合,发现大周期正方格子起缺陷作用.并发现当a2<5a时,缺陷态明显地随入射角度变化.此变化随a2的增大而减少.用FDTD方法计算了其透射和反射谱,结果表明缺陷峰透射率与a2的大小成反比.另外还发现: 缺陷峰结构与大周期正方格子的圆柱直径的关系曲线与a2关系不大.通过调节大周期正方格子的圆柱的直径,可获得单
关键词:
光子晶体
光子能隙
复式结构
缺陷态 相似文献
985.
A novel finite point method is developed to simulate flow problems. The mashes in the traditional numerical methods are supplanted by the distribution of points in the calculation domain. A local interpolation based on the properties of Taylor series expansion is used to construct an approximation for unknown functions and their derivatives. An upwind‐dominated scheme is proposed to efficiently handle the non‐linear convection. Comparison with the finite difference solutions for the two‐dimensional driven cavity flow and the experimental results for flow around a cylinder shows that the present method is capable of satisfactorily predicting the flow separation characteristic. The present algorithm is simple and flexible for complex geometric boundary. The influence of the point distribution on computation time and accuracy of results is included. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
986.
Herbert H.H. Homeier 《Numerical Algorithms》1998,17(3-4):223-239
The stability of a large class of nonlinear sequence transformations is analyzed. Considered are variants of the J transformation [17]. Suitable variants of this transformation belong to the most successful extrapolation algorithms that
are known [20]. Similar to recent results of Sidi, it is proved that the
p
{J} transformations, the Weniger S transformation, the Levin transformation and a special case of the generalized Richardson extrapolation process of Sidi are
S-stable. An efficient algorithm for the calculation of stability indices is presented. A numerical example demonstrates the
validity of the approach.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
987.
对武汉大学电波综合观测站于1991年的降雨曲线进行测量,当采样时间为5min时,用单变量雨强时间序列进一步研究了降雨这一大气过程中雨强分维数随时间的变化特性.结果表明,在灾害性降雨天气前后其雨强分维数仍然发生了显著性的改变. 相似文献
988.
双氟取代苯和联苯类液晶化合物的量子化学研究 总被引:1,自引:1,他引:0
运用AM1和PM3两种SCF-MO方法,通过能量梯度全优化计算,给出了对一系列环上双氟取代苯、联苯液晶化合物的稳定几何构型、电子结构和分子基本性质(生成热、偶极矩、前沿分子轨道能级等)。联系有机结构理论进行了分析和讨论。初步阐明了其分子结构与介电各向异性之间的关系,为设计和开发新型液晶分子研究提供了有较大价值的线索。 相似文献
989.
For an automatic testing of the fiber bending loss parameter, we proposed an on-line fiber optic bending loss measurement system. Many impact factors from the supporting systems, free space coupling alignment, external spatial perturbation device and the other automatic testing systems may degrade the on-line fiber-optic bending loss measurement system. We reduce those impact factors and show the mechanical and electrical improvement in this paper. The accuracy can be improved by 3–5 dB for the proposed on-line bending loss measurement system. Development of an on-line fiber-optic bending loss measurement system can provide a fast-checking solution for jump-line quality improvement on fiber-from-the-desk (FFTD) access network. 相似文献
990.