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Submonolayer Bi and Au adsorptions on the GaAs(001)-2× 4 surface are investigated by scanning tunnelling microscopy, low energy electron diffraction and first-principles calculations. The 1 ×4 and 3 × 4 reconstructed surface induced by Bi and Au, respectively, are revealed and their structural models are proposed based on experiments and first-principles calculations. Moreover, the validity of the recently proposed generalized electron counting (GEC) model [Phys. Rev. Lett. 97 (2006) 126103] is examined in detail by using the two surfaces. The GEC model perfectly explains the structural features, such Bi-1 × 4 surface and the 3x arrangement of four-atom Au as the characteristic short double-line structure in the clusters. 相似文献
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公路工程施工是一项比较复杂的建筑工程,其建设周期长,施工环境也复杂,在施工的过程中还存在很大的安全隐患。为了避免安全事故的发生,积极采取科学有效的管理措施就显得尤为重要。想要在有限的人力资源中实现对安全事故的有效管理就必须积极的采用物联网技术,在公路工程的施工过程中积极采用物联网技术,可以在很大程度上克服传统的安全管理模式所存在的缺陷,能够对安全问题进行及时的预警,并且在此基础上进行有效的消除。进而有效保障公路工程的施工安全。 相似文献
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研究了在超临界乙醇中、氢气存在下,一系列金属-酸双功能催化剂的酸性、孔径大小、负载的金属对热解木质素加氢裂解过程的影响.制备并采用N2等温吸附和BET比表面、X射线衍射、NH3-程序升温脱附技术对催化剂进行表征.实验结果表明催化剂酸性增强可促进热解木质素的缩聚反应,从而产生大量的焦炭和水,导致其液化效率降低.微孔催化剂比介孔催化剂孔径小,与强酸共同作用会导致热解木质素裂解生成更多的小分子气体.在催化剂上负载金属Ru可有效地抑制热解木质素的缩聚反应,促进其裂解液化. 相似文献
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Lattice-matched InGaAs/lnP heterostructures have been grown by using metalorganic vapor phase epitaxy (MOVPE) with tertiarybutylarsine
(TBAs), tertiarybutylphosphine (TBP) as the group V sources. The results of X-ray diffraction on InGaAs/lnP single herterostructure
show that there is a compressive-strained interfacial layer at the InP-to-InGaAs interface. X-ray diffraction of InGaAs/ InP
superlattices is successfully simulated by using the same interfacial layer. TBAs purging of InP surface has a significant
influence on the interfacial strain. A novel gas switching sequence, which switches group III to the run line earlier than
TBAs, is proposed to reduce this interfacial strain. As a result, the average compressive strain of superlattices decreases,
and a blue shift of photoluminescence ( PL) peak energy and narrowing in PL width are obtained. 相似文献
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Oscillatory electron phonon coupling in Pb/Si(111)deduced by temperature-dependent quantum well states 下载免费PDF全文
Photoemission study of atomically flat Pb films with a thickness from 15 to 24 monolayers (ML) have been performed within a temperature range 75-270K. Well-defined quantum well states (QWSs) are observed, which exhibit interesting temperature-dependent behaviours. The peak position of the QWSs shifts towards higher binding energy with increasing substrate temperature, whereas the peak width broadens linearly due to enhanced electron-phonon coupling strength (λ). An oscillatory A with a period of 2ML is deduced. Preliminary analysis shows that the oscillation can be explained in terms of the interface induced phase variations, and is thus a manifestation of the quantum size effects. 相似文献
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从常规电子产品热设计基础理论的理解分析入手,结合实际应用,阐述了混合集成电路典型装配结构热阻的简便分析方法;绘制了多种典型结构的内热阻与发热芯片面积的关系曲线和外热阻与封装表面积的关系曲线;提出了通过典型结构热阻曲线分析产品芯片结温的方法,及相应问题的处理办法;对一般混合集成电路的非精确热设计有一定的参考意义。 相似文献
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激发态分子内质子转移因其独特的光学性质而受到研究人员的青睐. 然而,关于改变原子电负性对激发态分子内质子转移过程和光物理性质影响的系统研究相对较少. 本文通过理论方法选择了一系列苯并噁唑异硫氰酸酯荧光染料(2-HOB、2-HSB 和2-HSeB),并通过改变氧族原子的电负性,系统地研究了激发态分子内质子转移过程和光物理性质. 计算的键角、键长、能隙和红外光谱分析表明,3个分子的分子内氢键强度依次为2-HOB<2-HSB<2-HSeB. 相应地,势能曲线的能垒大小为2-HOB>2-HSB>2-HSeB. 此外,计算的电子光谱表明,随着原子电负性的降低,发射光谱发生红移. 本工作将为基于激发态分子内质子转移性质的新型染料的合成和应用提供一定的理论指导. 相似文献
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量子尺寸效应导致的铅薄膜材料的奇异超导性质 总被引:1,自引:0,他引:1
我们在硅衬底上制备出厚度在原子尺度上可控、宏观尺度上均匀的铅薄膜。观察到随着厚度一个原子层一个原子层增加时薄膜超导转变温度的振荡现象。我们证明,这种振荡行为是量子尺寸效应的结果。在这种薄膜中,电子德布罗意波的干涉行为类同于光的法布里一玻罗干涉,会导致量子阱态的形成。量子阱态的形成改变了费米能级附近的电子态密度和电声子耦合强度,从而最后导致了超导转变温度的变化。研究结果表明:通过精确控制这种厚度敏感的量子尺寸效应,可以调制材料的物理和化学性质。 相似文献
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