Likun Wang (Ho Group) and Hiroaki Maekawa (Ge Group) - CaSTL Seminar

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Join meeting on Thursday, April 4, 2019 @ 1pm. Click on link below...

https://zoom.us/j/127130761

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1:00pm - Likun Wang

UC Irvine, Ho Group

Title: Photoinduced Dehydrogenation of a Single Molecule Adsorbed on a Surface

Abstract: Photons can be coupled with tunneling electrons to induce a chemical reaction of a molecule adsorbed on a surface in the junction of a scanning tunneling microscope (STM). Here, by using the combination of a low temperature STM with a femtosecond laser, we demonstrated the control and characterization of the dehydrogenation in a unimolecular reaction with atomic scale resolution. A single acetylene (HCCH) molecule can be sequentially dehydrogenated into ethynyl (CCH) and dicarbon (CC). While both reaction steps can be induced by tunneling electrons, only the C-H bond activation of the ethynyl could also be proceeded by the coupling of the tunneling electron with a photon. These studies provide us new insights into single molecule photochemistry with atomic scale precision.

Bio: Likun is a fourth-year PhD student in Physics advised by Prof. Wilson Ho. My research focuses on the study of single molecule on surface using laser coupled scanning tunneling microscope (STM).  I’m also involved in developing instrumentation in the lab, such as building helium recycling system, upgrading STM and optimizing our femto-second laser system.

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Abstract: Optical responses in the mid-IR wavelength region is highly useful in material characterization, identification of chemical species and detection of external perturbation. However, intrinsically poor spatial resolution on the order of micrometer restricts the application of conventional mid-IR spectroscopic and microscopic approaches to study properties and dynamics characteristic of systems in nanometer scale. Scattering scanning near-field optical microscopy (s-SNOM) is one of the techniques that has been developed in the last two decades to measure the optical responses with spatial resolution of 20-30 nm irrespective of the wavelength of probe light. In this talk, our recent experimental efforts of mid-IR s-SNOM, including femtosecond time-resolved measurement will be presented.

Bio: Hiroaki is an associate specialist in Prof. Ge’s group of UC Irvine. His research contributions in the group include femtosecond two-dimensional infrared spectroscopy, vibrationally resonant sum-frequency spectroscopy, nonlinear microscopy as well as s-SNOM to study molecular conformation and dynamics in the condensed phases