National Synchrotron Light Source Seminar
"From Graphite to Graphene via Scanning Tunneling Microscopy"
Dejun Qi, Department of Physics, University of Arkansas,
Wednesday, May 8, 2013, 10 am
Seminar Room, Bldg. 725
Hosted by: Evgeny Nazaretski
The discovery of graphene, a unique two- dimensional electron system with extraordinary physical properties, has ignited tremendous research activity in both science and technology. Graphene can be obtained from graphite by moving its top layer until it becomes locally decoupled from the bulk. However, a detailed microscopic understanding of this process has yet to be completed. Here a series of measurements on HOPG surface using a technique called electrostatic-manipulation scanning tunneling microscopy (EM-STM) are presented. These measurements successfully reduce the interplanar coupling strength between top plane of graphite and the bulk resulting in transition from graphite to graphene. In addition, STM images which reveal several intermediate stages in between pure graphene and pure graphite are also presented. Density functional theory was used to simulate STM images from a six-layer slab of graphite. A continuous transition from pure graphite to pure graphene was observed with the simulations.