学术报告
题目：Excited-state localization and relaxation of low-dimensional silicon nanostructures
报告人：张瑞勤教授
联系人：陈克求 教授
时间：2014年11月25日（星期二）上午10：00－11：00
地点：物理楼307（学术报告厅）
报告内容简介：Low dimensional silicon nanomaterials offer promising applications in nanoelectronics, photovoltaics and thermoelectronics, facilitated by their large surface-to-volume ratio and quantum confinement effects. Their excited-state properties are particularly interesting and show many novel features. In this presentation, I will describe the excited-state novel properties of zero-dimensional silicon quantum dots, one-dimensional silicon nanowires and two-dimensional silicon nanosheet. Due to their finite size and the significant localization of their electrons upon excitation, silicon nanostructures in excited states genergally undergo severe relaxation and thus show significant Stokes shift at a diameter less than 1.5 nm for quantum dots and 2.6 nm for nanosheets. The effect is much reduced at a larger size due to the improved structural rigidity and also the delocalization of the excited electrons. The latter can also be achieved by elongating the nanostructure in a certain direction. In addition, the boundary or surface could influence the degree of localization of the excited state. Silicon nanosheets are more easily to form self-trapped exciton. Our findings are helpful for designing silicon nanostructures for optoelectronic applications.
报告人简介：张瑞勤博士，香港城市大学教授、香港物理学会主席。主要研究包括：纳米功能材料的微观结构及其生长机理、电子传输、光学性质和磁学性质，功能小分子及分子簇的构象、性质及化学反应，气-固表面相互作用，纳米功能材料与生物体系、化学体系之间（弱）相互作用等方面，发展了一些相关的理论和计算方法。已在Science, Phys. Rev. Lett, Angew. Chem. Int. Ed.等刊物发表学术论文290余篇，他引5200余次，h-index 为 35（详见ResearcherID: L-8947-2014）。研究多为原子与分子物理、化学物理、物理化学、材料科学、凝聚相物理等多学科交叉课题。担任多个国际学术刊物编委。获得国家自然科学二、三等奖以及教育部科技进步一等奖，2004年获德国洪堡基金会贝塞尔研究奖。
