Dr. Zikang Tang, Chair and Professor

Director of Institute of Applied Physics and Materials Engineering, University of Macau

Visible Laser Beam as an Atomic Ruler for Measurement of Atomic Van der Waals Radius

Abstract:

We demonstrate a technique to determine the Van der Waals radius of an iodine atom using Raman scattering. The iodine diatomic molecules are diffused into the nano channels of a zeolite single crystal. Their polarized Raman spectroscopy, which corresponds to iodine molecule’s vibrational motion along the direction of molecular axis, is significantly modified by the rigid wall of the nano-channels. From the number of excitable vibration quantum states of the confined iodine molecules determined from Raman spectra and the size of the nano-channels, we determined the iodine atomic radius to be 2.10±0.05 Å, with a pretty good accuracy although its scale is far beyond the diffraction limit of the visible laser wavelength.

Biography:

Currently is Chair Professor and Director of Institute of Applied Physics and Materials Engineering, University of Macau. Before he joined to University of Macau in Jan 2016, he has been working for Hong Kong University of Science and Technology, as professor in the Department of Physics.

Prof. Tang is a pioneer in research on wide bandgap semiconductor photo-electronic physics and devices. With outstanding achievements in the field of zinc oxide ultraviolet lasing materials and devices, he won a State Natural Science Award (2nd class) in 2003. In 2000, he developed a unique technique to produce the world’s smallest single-walled carbon nanotubes (SWNTs), with diameter of only 0.4 nm, which has been hailed as a revolutionary epoch-making material. Later, he observed novel one-dimensional superconductivity in these ultra-small SWNTs, causing a stir in the global scientific community. He was among the first group of professors recruited under China’s “Thousand Talent Scheme”. He has published more than 300 papers in prestigious international journals, with citation frequency of over 12100 times. His pioneer research work on zinc oxide ultraviolet laser emission published on Applied Physics Letters is among the top 50 most cited papers in the past 50 years listed in the special 50th Anniversary edition of Applied Physics Letters.