报 告 人:盛卫东 (复旦大学 物理系)
报告题目:石墨烯纳米点中的暗激子
报告时间:2019年12月15号(周日)下午 4:00-5:00
报告地点:理科楼 0638太阳集团 LE201
邀 请 人:谢航
内容简介:
We here report a theoretical study of the excitonic effect in the optical absorption in graphene nanodots by using a configuration interaction approach. For a triangular nanodot system, we find that all the excited singlet states are optically dark in the absorption. These dark excitons are shown to originate mainly from the geometric symmetry of the system and would remain inactive even when the electron-hole or sublattice symmetry is broken. In most cases, the first excited state of the nanodot is a singlet and therefore we further reveal that these dark excitons would lead to an abnormal blueshift of the absorption edge. By contrast, the exciton binding energy increases and the corresponding excitonic transition would exhibit a redshift in the spectrum in a conventional semiconductor when the dielectric screening effect is suppressed.
报告人简介:
盛卫东教授,上海交通大学学士 (1991),硕士 (1994),中国科学院半导体研究所博士 (1997),瑞典隆德大学访问学者(1997—1999),美国伊莉诺依大学博士后(1999—2002),加拿大国立研究院助理、副研究员 (2002—2006)。2006年起任复旦大学物理系教授,博士生导师。研究领域:计算凝聚态物理,主要方向为小量子体系的电子结构,光学性质,及多体效应等,具体包括:外磁场下自组织量子点中电子态的研究,纳米小量子系统中电子自旋态的理论研究,量子点纳米系统中多电子和多激子态的研究。