Presenter: Prof. Xiaoji Xu (Lehigh University)
Topic: Peak Force Infrared Microscopy: Nanoscale Infrared Microscopy with sub 10 nm Spatial Resolution
Time: 9:30 a.m., Dec. 18th (Monday)
Location: Conference Room B, BLDG 909-1F
While Abbe’s optical diffraction limit prevents nanometer-scale spatial resolution for conventional microscopy and spectroscopy, the combination of optics and scanning probe microscopy provides a way to bypass the diffraction limit. One type of imaging technique is to utilize the near-field light scattering from a metallic AFM tip to locally probe the optical properties of the sample. The other type of high spatial resolution imaging technique is to measure the light-induced thermal expansions in the sample and related that to the local optical or infrared absorption. In the first part of the presentation, I will first present our latest invention of peak force infrared (PFIR) microscopy that provides infrared imaging, broadband spectroscopy, and mechanical property mapping at a spatial resolution as high as 6 nm. I will describe applications of PFIR microscopy on the characterization of block copolymers, urban aerosols (particulate matter PM2.5), organic photovoltaics and bacterial cell walls. Then, I will describe our recent development of the scattering-type infrared near-field microscopy for three-dimensional mapping of near-field responses of polaritonic materials and a route to incorporate scattering-type infrared near-field microscopy with ultrafast lasers. The exploration of nanoscale phenomena will be facilitated by these nanoscale infrared imaging techniques in revealing hidden secrets of the nanoworld.
Xiaoji Xu established his research group at Lehigh University as an assistant professor since 2014. Before at Lehigh University, he was a postdoctoral fellow at the University of Toronto, and University Colorado Boulder. He received his B.S. in Chemistry from Peking University in 2004 and Ph.D. in Chemical Physics from The University of British Columbia, Vancouver, Canada in 2009. His research focus is on chemical sensitive nanoscale imaging, ultrafast laser spectroscopy, and development of the analytical instrumentation. He holds three patents (licensed to industrial partners). Since he joined Lehigh, he has published seven papers including Nat. Commun., Sci. Adv. and ChemCommun and received the Class’ 68 research fellowship from Lehigh University.
Contact: Prof. Le He