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91.
92.
Carrier recombination and electron spin relaxation dynamics in asymmetric n-doped (110) GaAs/AlGaAs quantum wells are investigated with time-resolved pump-probe spectroscopy. The experiment results reveal that the measured carrier recombination time depends strongly on the polarization of pump pulse. With the same pump photon flux densities, the recombination time of spin-polarized carriers is always longer than that of the spin-balanced carriers except at low pump photon flux densities, this anomaly originates from the polarization-sensitive nonlinear absorption effect. Differing from the traditional views, in the low carrier density regime, the D'yakonov–Perel' (DP) mechanism can be more important than the Bir–Aronov–Pikus (BAP) mechanism, since the DP mechanism takes effect, the spin relaxation time in (110) GaAs QWs is shortened obviously via asymmetric doping. 相似文献
93.
Assessing Density Functionals for Describing Methane Dissociative Chemisorption on Pt(110)-(2×1) Surface 下载免费PDF全文
Fenfei Wei Egidius W.F. Smeets Johannes Voss Geert-Jan Kroes Sen Lin Hua Guo 《化学物理学报(中文版)》2021,34(6):883-895
In this work, we explore the suitability of several density functionals with the generalized gradient approximation (GGA) and beyond for describing the dissociative chemisorption of methane on the reconstructed Pt(110)-(2\begin{document}$ \times $\end{document} 1) surface. The bulk and surface structures of the metal, methane adsorption energy, and dissociation barrier are used to assess the functionals. A van der Waals corrected GGA functional (optPBE-vdW) and a meta-GGA functional with van der Waals correction (MS PBEl-rVV10) are selected for ab initio molecular dynamics calculations of the sticking probability. Our results suggest that the use of these two functionals may lead to a better agreement with existing experimental results, thus serving as a good starting point for future development of reliable machine-learned potential energy surfaces for the dissociation of methane on the Pt(110)-(2\begin{document}$ \times $\end{document} 1) surface. 相似文献
94.
The hydrogen adsorption on polycrystalline platinum electrode experimentally as well as on single crystal Pt(110), Pt(100) and Pt(111) electrode theoretically were studied. The study of forced convection on the electrode surface promotes the HUPD research from static process to a convective mode and provides a new strategy to investigate the hydrogen adsorption in solution. 相似文献
95.
通过微波等离子体化学气相淀积技术生长单晶金刚石并切割得到(110)和(111)晶面金刚石片,以同批器件工艺制备两种晶面上栅长为6μm的氢终端单晶金刚石场效应管,从材料和器件特性两方面对两种晶面金刚石进行对比分析.(110)面和(111)面金刚石的表面形貌在氢终端处理后显著不同,光学性质则彼此相似.VGS=–4 V时,(111)金刚石器件获得的最大饱和电流为80.41 m A/mm,约为(110)金刚石器件的1.4倍;其导通电阻为48.51 W·mm,只有(110)金刚石器件导通电阻的67%.通过对器件电容-电压特性曲线的分析得到,(111)金刚石器件沟道中最大载流子密度与(110)金刚石器件差异不大.分析认为,(111)金刚石器件获得更高饱和电流和更低导通电阻,应归因于较低的方阻. 相似文献
96.
97.
张福兰 《原子与分子物理学报》2011,28(1)
采用密度泛函理论与周期平板模型相结合的方法,对物种CHx(x=2~4)在Fe(110)表面的top,hcp,SB和LB位的吸附模型进行了结构优化、能量计算,得到了各物种较有利的吸附位;并对最佳吸附位进行密立根电荷和总态密度分析。结果表明:CH4在Fe(110)表面的最稳定吸附位都是SB位,吸附能别是-38.14 kJ•mol-1,CH3在Fe(110)表面的最稳定吸附位都是top位,吸附能别是-171.78 kJ•mol-1,而CH2在Fe(110)表面的最稳定吸附位hcp的吸附能是-342.43 kJ•mol-1;CH3 和CH2两物种与金属表面成键,属于化学吸附。 相似文献
98.
The density functional theory(DFT) and self-consistent periodic calculation were used to investigate the C2Hx(x = 4~6) species adsorption on the Fe(110) surface. The adsorption energy and equilibrium geometry of the species C2Hx(x = 4~6) on four possible sites(top,hcp,SB and LB) on the Fe(110) surface were predicted and compared. Mulliken charges and density of states analysis of the most stable site have been discussed. It is found that the species of C2H6 and C2H5 are adsorbed strongly on the Fe(110) surface with calculated adsorption energy of -80.24 and -178.89 kJ·mol-1 at the Fe-LB(long-bridge) ,respectively. However,the C2H4 is adsorbed strongly on the Fe(110) surface with calculated adsorption energies of -114.96 kJ·mol-1 at the top. The results indicate that the charge transferring process can be completed by chemisorption between Fe(110) surface and the species. Moreover,the chemical bands can be formed by chemisorptions between the Fe(110) surface and the species,too. 相似文献
99.
Ke Liu 《Analytica chimica acta》2009,651(1):85-781
The ability to quickly measure flow parameters in microfluidic devices is critical for micro total analysis system (μTAS) applications. Macrofluidic methods to assess flow suffer from limitations that have made conventional methods unsuitable for the flow behavior profiling. Single molecule fluorescence correlation spectroscopy (FCS) has been employed in our study to characterize the fluidic vortex generating at a T-shape junction of microscale channels. Due to its high spatial and temporal resolution, the corresponding magnitudes relative to different flow rates in the main channel can be quantitatively differentiated using flow time (τF) measurements of dye molecules traversing the detection volume in buffer solution. Despite the parabolic flow in the channel upstream, a heterogeneous distribution of flow has been detected across the channel intersection. In addition, our current observations also confirmed the aspect of vortex-shaped flow in low-shear design that was developed previously for cell culture. This approach not only overcomes many technical barriers for examining hydrodynamic vortices and movements in miniature structures without physically integrating any probes, but it is also especially useful for the hydrodynamic studies in polymer-glass based micro -reactor and -mixer. 相似文献
100.
Zur Unlersuchung des Materia1transports aus einem Elektrolyten in eine feste Metallprobe während mechanischer Bearbeitung wurde ein Schichtabtragungsverfahren mit Messung der Restaktivität eingesetzt. Die einzelnen abgetragenen Schichten waren etwa 1 μm dick. Das Verfahren wurde an Cu-Material erprobt, in das 65Zn aus einer ZnCl2-Lösung eingedrungen war. Die Probenbearbeitung erfolgte auf tribogalvanischem Wege. 相似文献