Colloquium
Department of Physics, NCU
VUV Photoelectron Spectroscopy of Aqueous Aerosols and Its Implications in the Biological and Environmental Sciences
Speaker
王家蓁教授 (Prof. Chia C. Wang)
Department of Chemistry, National Sun Yat-sen University
Date 2016.05.10(Tue)
Time 14:00
Place S4-625
「歡迎大學部同學參加，可獲得中大護照認證2小時」
Abstract
The crucial roles of aerosols have been increasingly recognized in a variety of important fields, encompassing the atmospheric chemistry, the environmental science and the planetary science. Recently, the implications of aerosols in the biomedical science, pharmaceutical administration and micro-fabrications of nano-structured materials have also been actively explored. To probe the valence electronic structure of aerosols, which decisively determines their chemical activities, an aerosol VUV photoelectron spectroscopy apparatus equipped with a high resolution hemispherical energy analyzer has been recently built, using the VUV radiation generated from the undulator beamline (U9) at the National Synchrotron Radiation Research Center (NSRRC) in Taiwan as the ionization source. Preliminary efforts have been focused on studying the aqueous aerosols. By introducing the aqueous samples of interest into the aerosol phase and collimating them into a focused nanoparticle beam via an adjustable aerodynamic lens (AADL) system, this new aerosol apparatus readily creates a microscopic aqueous environment, which allows ones to study the hydrated structure of biologically important materials and extract valuable information that can only be accessed under relevant aqueous conditions, such as the solvent effect, pH effect and the solvent-solute interaction. Recently, we applied this newly constructed aerosol VUV photoelectron spectroscopy apparatus to investigate the valence electronic structure of several biological important amino acids and small peptides, including cysteine, glutamic acid and glutathione aqueous aerosols for the first time. The effect of pH value on the electronic properties of the chosen aqueous aerosols has been interrogated. The newly developed aerosol VUV photoelectron spectroscopy technique not only exhibits the capability to probe the solvated species, but also sheds new light for one to investigate the valence electronic structure of aerosols and complex molecular assemblies in a size-selective and composition-controlled way, as well as their evolution into the bulk. With this new aerosol investigation tool, it is promising to address numerous fundamental but critical issues regarding aerosols in their related fields, including the environmental science, the atmospheric chemistry and the biomedical science.
References:1. Chien-Cheng Su, Youqing Yu, Po-Chiao Chang, Yu-Wei Chen, I-Ying Chen, Yin-Yu Lee and Chia C. Wang*, J. Phys. Chem. Lett. 6, 817 (2015)