Visualization of Molecular Vibration with Inelastic Electron Tunneling and Photon
Dr. Shaowei Li
Department of Chemistry and Biochemistry
UC San Diego
Abstract: A molecule’s vibrational and rotational features contain rich information about its chemical conformation and are broadly used as fingerprinting signatures for chemical identification. Though the homogeneous vibrational/rotational properties of chemicals have been extensively explored at the ensembled level with infrared adsorption, Raman scattering, and/or microwave spectroscopy, the inhomogeneous characters of individual molecules in response to the nano-scale variation in their chemical environment remains a rarely explored territory. In this talk, I will introduce two STM-based approaches my team uses to explore the rotation/vibration of molecules. In the first approach, the electrons tunneling inelastically to the molecules can trigger the molecular rotation/vibration with sub-molecular precision. In the second approach, the nucleus motion in a molecule is excited by light and probed locally with tunneling electrons. These two approaches provide a window to view the inhomogeneous characteristics of vibrations/rotations, and enable the investigation of their transient dynamics with joint spatial-temporal resolution.
Bio: Dr. Shaowei Li is an assistant professor at the University of California, San Diego. He received B.S. in Mathematics and Physics from Nankai University in 2010 and Ph.D. in physics from the University of California, Irvine in 2017. Before joining UC San Diego, he was a postdoc scholar at Northwestern University and later a Heising-Simons Junior Fellow at UC Berkeley. His research focuses on probing the fundamental properties of low-dimensional systems including single molecules and correlated 2D materials with scanning tunneling microscopy and spectroscopy. His group combines scanning tunneling microscopy with ultrafast laser spectroscopy to explore nano-scale objects with angstrom-scale spatial resolution and femtosecond-level temporal resolution.
Hosted by Prof. Assaf