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991.
Dominic R. Alfonso 《Surface science》2006,600(19):4508-4516
Density functional theory is used to investigate the initial inclusion of sulfur into the subsurface interstitial sites of Pd(1 1 1) surface. Pure subsurface adsorption is found to be less energetically favorable than on-surface adsorption. The incorporation of sulfur into the metal becomes more favorable than continuous adsorption on the surface after a critical on-surface sulfur coverage. We find subsurface sulfur occupation to be energetically favorable after adsorption of more than half a monolayer on the surface. Occupation of subsurface sites induces a pronounced structural distortion of the Pd(1 1 1) surface. We find significant expansion of interplanar spacing between the uppermost surface metal layers and rearrangement of the S overlayer. The interplay between the energy cost due to structural distortion of Pd(1 1 1) and the energy gain due to bond formation for different structures is discussed. 相似文献
992.
首次合成了肽键桥连的四苯卟啉-蒽醌(TPP-AQ)化合物,以此作为研究光合成电子传递的模型化合物,用时间相关单光子荧光技术研究了该化合物在不同溶剂中分子内的电子转移。 相似文献
993.
The chemistry of dimethyl mercury on a Pt(111) single crystal surface has been investigated by reflection-absorption infrared spectroscopy (RAIRS). Dimethyl mercury appears to be highly reactive on Pt(111) and readily decomposes on the surface at temperatures of 100 K and above. Adsorption at 100 K initially occurs in a dissociative manner to produce CH3 and CH3Hg species on the surface, both of which are identified as having C3v local symmetry. At higher exposures, molecular adsorption dominates with the Hg---C---Hg axis initially oriented parallel to the surface. This preferred orientation, however, does not persist into the multilayer. Thermal treatment of the surface layer results in multilayer desorption between 130 and 135 K, and no parent molecular species are observed beyond 160 K. Adsorption at 200 and 300 K produces an overlayer consisting primarily of CH3Hg species, which are thermally stable to about 350 K. Subsequent heating to 400 K results in the formation of ethylidyne species which are characterised by RAIRS. Adsorption at 400 K results in the direct formation of an ethylidyne layer estimated to be about 85% of saturated coverage. 相似文献
994.
The effects of the compensation ratio with dispersion post-compensation on nonlinear single channel and WDM systems with 10 Gb/s per channel are numerically investigated. When the transmission signal per channel is 10 Gb/s RZ pulse and the amplifier span is 50 km, proper undercompensation can enhance the performance of the nonlinear single channel system and the nonlinear WDM system. But the enhanced distance of the nonlinear WDM system is not as obvious as that of the single channel system, because the cross-phase-modulation effect plays an important role in the nonlinear WDM system. 相似文献
995.
The ASED-MO method has been used to gather electronic and energetic information on Pd deposits on Ni(111) and Pd atom inclusion in the first Ni layer since these model catalysts exhibit a striking catalytic efficiency towards butadiene hydrogenation. The electronic structure of Pd atoms is strongly altered compared with pure Pd. A Pd(4d)→Pd(5s) electronic transfer occurs in the case of the deposit when a slight similar transfer and a charge transfer from Pd to surrounding Ni takes place in the case of the inclusion. Those results are consistent with XPS experimental data. A low density of states, near the Fermi level, is also observed. The optimal geometrical situation for Pd deposits is found to be 2D-aggregates (in pseudoepitaxy or pseudomorphy with the underlying Ni surface, depending on the aggregate size). Small aggregates (part of the first Ni layer) are found to be the most stable in the case of a Pd inclusion in the Ni with a Pd---Pd distance of 2.64 Å, in agreement with available EXAFS experimental data. 相似文献
996.
997.
单模光纤偏振特性的测试 总被引:4,自引:0,他引:4
叙述测量单模光纤偏振特性的基本原理,介绍了单模光纤的偏振度P,位相差δ及保偏光纤的拍长Lp的测量方法。 相似文献
998.
The 6.4 GHz ECR ion source that was indigenously developed a few years ago has been operating continuously for injecting oxygen
and neon beams to the cyclotron since 1997. VEC-ECR is a single stage high magnetic field ion source provided with a negatively
biased electron repeller placed on the axis, near the injection mirror point. The supply of cold electrons and use of low
mass mixing gas improve the stability of ECR plasma. Very recently, the effect of aluminum oxide coating on the copper plasma
chamber wall has been studied. The plasma chamber wall was coated with aluminum by vacuum evaporation method and then exposed
to oxygen gas to form aluminum oxide. It was noticed that the process substantially shifts the charge state distribution to
the higher charge state with an enhancement of ion current by an order of magnitude. With the aluminized plasma chamber, the
VEC-ECR can now produce 12 μA of O7+, 6.5 μA of Ar12+, 1.5 μA of Kr20+ and 1.0 μA of Xe31+. 相似文献
999.
The global existence and finite time blow up of the positive solution for a nonlinear degenerate parabolic equation with non-local source are studied. 相似文献
1000.
Tracking an active sound source involves the modeling of non-linear non-Gaussian systems. To address this problem, this paper proposed scaled unscented particle filter (SUPF) algorithm for tracking moving sound source. The particle filter part of the SUPF provides the general probabilistic framework to handle non-linear non-Gaussian systems, and the scaled unscented Kalman filter (SUKF) part of the SUPF generates better proposal distributions by taking into account the most recent observation. Meanwhile, models used in SUPF algorithm were also explored for the sound source motion, observation and the likelihood of the sound source location in the light of the Langevin process. Compared with the conventional PF approach, the simulated results demonstrated that the SUPF algorithm had superior tracking performance. 相似文献