Engineering sp2 Carbon Nanostructures with Electrons（2012.9.19） 时间：2012年9月21日(星期五) 上午 10:00；地点：武汉大学化学学院 化北323报告厅 内容提要：The Molecular Nanostructures group at the IFW conducts research on the synthesis of sp2 carbon nanostructures and other materials (e.g. Si, B, SiC, FexOy, Fe etc). Particular focus is placed on understanding the growth and functionalization mechanisms of these nanostructures. In addition, their potential for biomedical exploitation is investigated. We are also developing the use of electrons to structure, modify and grow nanostructures. The field can be classified into two primary categories, namely, current induced engineering and electron beam induced engineering. Both routes are highly versatile and afford the opportunity to cut/erode sp2 carbon, heal defects, and for catalyst-free fabrication of graphene from amorphous carbon. In this presentation in-situ transmission electron microscopy (TEM) studies exploring both current induced and electron beam engineering are presented. For the current induced studies graphene flakes suspended across electrodes are investigated at high bias. The studies provide a rich variety of phenomena that provide important insights into how one can shape or modify graphene by Joule heating. Examples include the peeling off of multilayered suspended graphene sheets layer by layer, the controlled cracking of graphene to nanoribbons as narrow as 1 nm which sustain currents as high as 6 x 109 A cm-2 and the merging of overlapping pieces of graphene. In addition, deposited amorphous carbon on suspended graphene at high bias is shown to graphitize. The use of an electron beam (from the TEM itself) is also shown to offer a plethora of engineering possibilities including, nano-chemistry inside single walled carbon nanotubes, catalyst free graphene fabrication, and sp2 carbon nanostructuring. The experimental work is supported by image simulation data and molecular dynamics simulations. 报告人简介：Mark H. Rümmeli (马克•赫尔曼•如姆里) 博士，1967年出生，德国莱布尼兹固体物理研究所研究员，玛丽·居里研究员(Marie Curie Fellow)。马克研究员和他领导的研究小组在碳纳米结构的生长机制研究与微观结构表征(高分辨透射电子显微镜)领域取得了一系列令人瞩目的工作。马克研究员迄今在Nature Nanotech., JACS, Nano Lett., Adv. Mater., Phys. Rev. Lett., ACS Nano等国际著名学术期刊上发表学术论文174篇，出版了4本学术著作，应邀作学术报告25次。 近期代表论文： 1. Graphene at High Bias: Cracking, Layer by Layer Sublimation, and Fusing, Nano Lett. 12 (2012) 1873. 2. Graphene: Piecing it Together, Adv. Mater. 23 (2011) 4471. 3. Structural Transformations in Graphene Studied with High Spatial and Temporal Resolution, Nature Nanotech. 4 (2009) 500. |
