SYNTHETIC INORGANIC AND MATERIALS CHEMISTRY

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 半导体量子线及其几何尺寸对量子限制的影响：量子限制效应是由于电子和空穴的几何限制，在半导体小晶体中发生的电子和光学性质的急剧变化。当被激发的纳米晶体中的电子-空穴对被压缩到接近体激子玻尔半径(~2-60 nm)的尺寸时，半导体的有效带隙随着纳米晶体尺寸的减小而增大。因此，量子限制的大小取决于纳米晶体的大小和组成。但是纳米晶体的形状呢？人们可能会合理地想知道哪种纳米晶体形状--量子井(层)、量子线、量子棒(短线)或量子点--应该表现出固有的更强的量子限制效应。答案在理论上是已知的：3D限制比2D限制更强，而2D限制又比1D限制更强。因此，量子限制的大小应该以有序的势垒、线棒和圆点的方式增加。我的团队现在正在为这些预测提供定量的实验验证。我们使用单分散金属-纳米粒子催化剂通过溶液化学生长可溶的、直径可控的量子线。与卢米斯教授合作，对金属丝进行光谱表征，从中确定它们的带隙和其他光学性质。量子线带隙和其他性质的尺寸依赖关系与相应的点、棒和势垒的大小依赖关系以及与王林博士(Lawrence Berkeley National Lab.)提供的高级理论计算结果进行了比较。我们的工作证实，健美运动员、长跑运动员、建筑师和量子力学都同意：在功能、性能和行为形状方面都很重要。 余华，李军，R.A.Loomis，王林伟，和W.E.Buhro，*《磷化铟导线和点中的二维和三维量子限制》，《自然材料》，2,517(2003)。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Semiconductor Quantum Wires and the Influence of Geometric Dimensionality on Quantum Confinement: Quantum-confinement effects are the dramatic changes in electronic and optical properties occurring in small semiconductor crystallites as a result of the geometric confinement of electrons and holes. When an electron-hole pair in an excited nanocrystal is squeezed into a dimension approaching the bulk exciton Bohr radius (~2-60 nm), the effective band gap of the semiconductor increases with decreas innanocrystal size. Thus, the magnitude of quantum confinement depends upon nanocrystal size and composition. But how about the nanocrystal shape? One may reasonably wonder which nanocrystal shape- the quantum well (layer), quantum wire, quantum rod (short wire), orquantum dot - should exhibit the inherently stronger quantum-confinement effects.The answer is known theoretically: 3D confinement is stronger than 2D confinement, which in turn is stronger than 1D confinement. Thus, the magnitude of quantum confinement should increase in the order wells < wires < rods < dots. My group is now providing quantitative experimental ver-ification of these predictions. We grow soluble, diameter-controlled quantum wires by solution chemistry using monodisperse metallic-nanoparticle catalysts. Spectroscopic characterization of the wires, from which their band gaps and other optical properties are determined, is conducted in collaboration with Prof. Loomis. The size dependences of the quantum-wire band gaps and other properties are compared to those of the corresponding dots, rods, and wells, and to the results of high-level theoretical calculations provided by the group of Dr. Lin-Wang Wang (Lawrence Berkeley National Lab.). Our work affirms that bodybuilders, distance runners, architects, and quantum mechanics all agree: in function, performance, and behavior - shape matters. H. Yu, J. Li, R.A. Loomis, L.-W. Wang, and W.E. Buhro,* "Two- versus three-dimensional quantum confinement in indium phosphide wires and dots," Nature Mater., 2, 517 (2003).