[Lecture] Studies of the Properties of Mechanically Deformed Graphene and Single Wall Carbon Nanotubes
Topic: Studies of the Properties of Mechanically Deformed Graphene and Single Wall Carbon Nanotubes
Speaker: Prof. Mingyuan Huang
Time: 10:00 am~12:00 am, Friday, Jan. 4th
Location: 215 meeting room, MSE building
Abstract:
Due to the extremely low density of defects, carbon nanotubes and graphene were predicted in theory and demonstrated experimentally to possess excellent mechanical properties and can sustain relatively large strain. This gives us an opportunity to explore the impact of mechanical deformation to their physical properties. In the presentation, the optical and electrical properties of mechanically deformed graphene and single wall carbon nanotubes (SWNTs) will be discussed. First, the studies about mechanical and electromechanical properties of the optical characterized SWNTs will be briefly introduced. It was predicted that strain can change the electronic structure dramatically and our Rayleigh scattering spectroscopy studies in strained SWNTs confirmed this prediction. Further, a systematic study of the Raman spectra of optical phonons in graphene monolayers under tunable uniaxial tensile stress will be presented. Under the stress, the doubly degenerated G band splits into two distinct sub-bands due to the strain-induced symmetry breaking and degeneracy lifting; the two-phonon intervalley 2D band also displays profound splitting and which can be understood by strain-induced electronic structure change; the two-phonon intravalley 2D’ band shows two different frequencies depending on the angle between the incident light polarization and strain axis and which reveals the anisotropy of the light absorption around the Dirac cone and the anisotropic phonon dispersion around the Brillouin zone center. Finally, the in-situ investigation of electro-mechanical coupling in graphene based device will be discussed. The in-situ nano-indentation experiment was performed on suspended graphene and the electrical properties were measured simultaneously.
Biosketch of the Speaker:
Mingyuan Huang received the B.S. and M.S. degrees in the department of mechanical engineering from the University of Science and Technology of China in 2001 and 2004, respectively. He received Ph.D degree with distinction in mechanical engineering from Columbia University in 2009. After that, he has been working as a post-doc in material science at California Institute of Technology. He joined Frontier Institute of Science and Technology (FIST) as a faculty member in 2012 and received 1000 Young Talented People Award. His research interests mainly focus on nano-materials, such as graphene and carbon nanotubes.
