7月4日讲座安排

报告题目:In Situ Molecular Imaging of the Air-Liquid Interface and the Solid-Liquid Interface Using Microfluidics
报告人:Dr. Xiao-Ying Yu(Senior Scientist, Pacific Northwest National Laboratory, USA)
报告时间:7月4日 上午10:00
报告地点:徐汇校区实验四楼207室


摘要:
    The air-water and solid-liquid interfaces have unique kinetics and thermodynamics, distinct from the bulk.  However, major surface analytical techniques are mostly vacuum-based and direct applications involving volatile liquids are difficult.  We developed a vacuum compatible microfluidic interface, System for Analysis at the Liquid Vacuum Interface (SALVI), to enable direct observations of the vacuum-liquid interface approximating the air-liquid interface and the solid-liquid interface using in situ time-of-flight secondary ion mass spectrometry (ToF-SIMS).  New results in the air-water interface of importance in atmospheric chemistry will be presented first.  Specifically, glyoxal photochemistry and dark aging as a source of aqueous secondary organic aerosols (aqSOAs) are investigated using our unique in situ molecular imaging approach.  The surface mixing states resulting from oxidation have been chemically mapped for the first time.  The effect of reaction time on oxidation products and oligomer formation is investigated.  Second, novel materials (i.e., switchable ionic liquids (SWILs), metal-organic frameworks (MOFs)) have been investigated using this unique molecular imaging approach.  For example, the evolving liquid-liquid interface is characterized in SWILs.  Effort is ongoing to decipher the formation mechanism in predictive material synthesis using in situ chemical imaging.  Moreover, we have demonstrated in situ probing of the solid electrode and liquid electrolyte solution interface (or solid-electrolyte interface, SEI) using an innovative electrochemical microreactor consisting of three electrodes.  It has provided the first direct observation of the surface and diffused layer of SEI in a liquid with chemical speciation using dynamic liquid SIMS.  Selected results from our latest in situ molecular imaging research will be presented, showcasing new directions and applications of multimodal imaging of environmental surfaces and complex material interfaces and studying chemistry from the bottom up, all based on microfluidics.  SALVI, a portable microfluidic reactor, sets the analytical foundation toward chemical imaging of complex phenomena occurring in multiple time and length scales, or the mesoscale, underpinning chemical changes at the molecular level in the condensed phase.