CAREER: Semiconductor Clusters: Chemistry at the Interface of Small Molecules and Quantum Dots

这项由大分子、超分子和纳米化学（MSN）项目颁发的职业奖支持哥伦比亚大学乔纳森·欧文教授的研究工作，该研究旨在了解纳米晶体半导体的成核和生长，以及它们与前体分子转化的关系。所提出的工作的核心重点包括两个部分：(i)前驱体转化的动力学和机制及其与团簇结晶及其随后转化为更大的纳米晶体的关系，无论是通过组装还是原子间的生长过程；（ii）通过系统地剪裁簇配位化学来表征和修改导致这些材料表面态发光的表面结构特征。通过研究原子精确的簇，指定负责捕获激子的特定结构元素和研究晶体生长机制都成为可能，其细节程度是使用传统材料和方法无法做到的。这一建议的广泛影响在于它对表面张力和胶体晶体成核的经典模型的重要性。了解团簇稳定性的起源将澄清团簇与更大的纳米晶体的区别，根据吉布斯-汤普森关系，纳米晶体的稳定性随着粒子尺寸的增加而增加。这种差异对纳米晶体的成核和生长机制有着重要的影响，并且与支撑经典成核理论的自由能论点形成鲜明对比。结构功能关系的研究被整合到K-8课程中，该课程教授分子结构对日常生活有形方面的重要性。通过将这一背景融入科学概念的教学中，使化学结构与年轻学生联系起来，促进他们对科学思维的广泛兴趣。

This CAREER award by the Macromolecular, Supramolecular, and Nanochemistry (MSN) program supports work by Professor Jonathan Owen at Columbia University - endowed to understand the nucleation and growth of nanocrystalline semiconductors and their relationship to the conversion of precursor molecules. The core focus of the proposed work consists of two parts: (i) The kinetics and mechanisms of precursor conversion and their relationship to the crystallization of clusters and their subsequent conversion into larger nanocrystals, whether by assembly or atom-by-atom growth processes; (ii) To characterize and modify the surface structural features that cause surface state luminescence in these materials by systematic tailoring of cluster coordination chemistry. By studying atomically precise clusters, the assignment of specific structural elements responsible for trapping of excitons and investigations of crystal growth mechanisms all become possible with a level of detail not possible using traditional materials and methods. The broader impact of this proposal rests in its importance to classical models of surface tension and the nucleation of colloidal crystals. Understanding the origins of cluster stability will clarify how clusters are distinct from larger nanocrystals where the stability increases with the particles dimensions according to the Gibbs-Thompson relationship. This difference has important consequences for nanocrystal nucleation and growth mechanisms and is in stark contrast to the free energy arguments that underpin classical nucleation theory. The study of structure function relationships is integrated into a K-8 curriculum that teaches the importance of molecular structure to tangible aspects of everyday life. By integrating this context into the teaching of scientific concepts, chemical structure is made relevant to young students, promoting broad interest in scientific thinking.