Elastic properties of CdSe/Zns core/shell nanorods and nanowires

CdSe/Zns核/壳纳米棒和纳米线的弹性性能

• 批准号: 26191643
• 负责人: Professor Dr. Christian Thomsen
• 金额: --
• 依托单位: Institut für Festkörperphysik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2006
• 资助国家: 德国
• 起止时间: 2005-12-31 至 2009-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/26191643?language=en
• 关键词: Elastic; properties; CdSe; Zns; core

The physical properties of nanowires or nanorods differ qualitatively from the corresponding bulk materials due to the reduced dimension. We plan to investigate the thermal properties of several nanostructures when illuminated and heated with visible light. The high surfaceto- volume ratio of nanostructures leads to an equilibrium temperature which is given mostly by the thermal conductivity of the surrounding gas and not by thermal conduction along the nanowire as often assumed in the literature. Si nanowires, e.g., can be used as gas-type or gaspressure sensors, since the thermal conductivity of a surrounding gas depends on its molecular weight and pressure. From the ¿ for most materials well-known ¿ temperature dependence of the phonon frequency the temperature of a nanostructure can be determined optically via Raman spectroscopy.Two limiting cases are particularly interesting: In vacuum the heat dissipation is dominated by radiation and thermal conduction along a nanowire. And secondly, when immersed in superfluid helium the thermal resistance (Kapitza resistance) at the interface of a nanostructure to liquid helium limits the cooling of the nanostructure. In nanostructures with core and shell materials ¿ a particularly important application of nanorods ¿ there is an additional interface which contributes to the thermal resistance. We plan to study the interface via the Kapitza resistance of Si-nanowires and CdSe nanorods in a region where it becomes the limiting physical effect for heat dissipation.Size quantization has an important influence on the electronic and vibrational states of a material in reduced dimension of nanowires which needs to be taken into account in the analysis. We will study with Raman scattering and luminescence the quantization in Si nanowires and CdSe nanorods. The experimental results are compared to results of molecular dynamics of the thermal properties and ab initio computations of the electronic and vibrational states.

由于尺寸降低，纳米线或纳米棒的物理特性与相应的散装材料不同。我们计划在用可见光照明并加热几种纳米结构的热性能。纳米结构的高表面体积比导致同样的温度，这主要是由于周围气体的导热率而给出的，而不是通过文献中经常假设的沿纳米线的热传导。 Si纳米线，例如，可以用作气体类型或气气传感器，因为周围气体的导热率取决于其分子量和压力。从大多数材料中，声子频率的温度依赖性可以通过拉曼光谱进行光学确定纳米结构的温度。两个限制案例特别有趣：在真空中，散热散热以辐射和沿纳米线的热传导为主。其次，当浸入纳米结构界面的热电阻（Kapitza电阻）中时，液态氦的界面会限制纳米结构的冷却。在带有核心和壳材料的纳米结构中»纳米棒特别重要的应用•还有一个额外的界面有助于热电阻。我们计划在一个区域中通过Si-nanovires和CDSE纳米棒的Kapitza耐药性研究界面，在该区域成为热量耗散的限制物理效应。尺寸量化对降低纳米尺寸的材料的电子和振动状态具有重要的影响，在分析中需要考虑到需要考虑的纳米尺寸。我们将以拉曼散射和发光研究SI纳米线和CDSE纳米棒的量化。将实验结果与电子和振动状态的热性能的分子动力学和从头开始计算进行了比较。