Electronic dynamics in unoccupied states of graphene

石墨烯未占据状态下的电子动力学

• 批准号: 172968903
• 负责人: Professor Dr. Helmut Zacharias
• 金额: --
• 依托单位: Center for Soft Nanoscience (SoN)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2010
• 资助国家: 德国
• 起止时间: 2009-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/172968903?language=en
• 关键词: Electronic; dynamics; unoccupied; states; graphene

In this project the dynamics in unoccupied electronic states of graphene nanoribbons and graphene sheets grown on Ni(111), intercalated with Au, and on SiC(0001) will be investigated. Measurements of the lifetimes are performed as a function of energy above the Fermi level in the vicinity of the K and of the M points. Due to the high parallel momentum of the electrons in these parts of the Brillouin zone ultrashort XUV pulses obtained from high harmonic generation of Ti:sapphire laser radiation have to be employed for the photoemission out of the excited states. A two-dimensional delay-line detector with time-of-flight option enables us to measure also the momentum relaxation in the unoccupied bands. We expect a different behavior near the K and M points of the Brillouin zone. A temporal delay of the XUV probe pulses with respect to visible or UV pump pulses enables us to trace these dynamics. The effect of doping the graphene, which shifts the unoccupied bands with respect to the Fermi level, shall also be studied for substrates which only weakly interact with the graphene. Various co-operation partners within the Priority Program contribute to reach these goals by providing chemicals for the defined growth of nanoribbons, Gr/SiC samples and theoretical insight into the dynamic behavior.

在该项目中，将研究在插入 Au 的 Ni(111) 和 SiC(0001) 上生长的石墨烯纳米带和石墨烯片的未占据电子态的动力学。寿命的测量是作为 K 点和 M 点附近费米能级以上能量的函数进行的。由于布里渊区这些部分中电子的高平行动量，必须采用从钛宝石激光辐射的高次谐波产生获得的超短 XUV 脉冲来实现激发态之外的光电发射。具有飞行时间选项的二维延迟线探测器使我们能够测量未占用带中的动量弛豫。我们预计布里渊区的 K 点和 M 点附近会出现不同的行为。 XUV 探针脉冲相对于可见光或 UV 泵浦脉冲的时间延迟使我们能够追踪这些动态。对于仅与石墨烯微弱相互作用的基底，还应研究石墨烯的掺杂效应，其相对于费米能级移动未占据的能带。优先计划内的各个合作伙伴通过提供用于纳米带、Gr/SiC 样品的特定生长的化学品以及对动态行为的理论洞察，为实现这些目标做出贡献。