AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Electrospray-Surface Enhanced Raman Spectroscopy (ES-SERS) for the Surface-Sensitive Characterization of Atmospherically Relevant Particles
Masao Gen, CHAK K. CHAN, City University of Hong Kong
Abstract Number: 50 Working Group: Aerosol Chemistry
Abstract We present an electrospray-surface enhanced Raman spectroscopy (ES-SERS) for measuring the surface chemical compositions of atmospherically relevant particles. The surface-sensitive SERS is realized by electrospraying Ag nanoparticle aerosols over particles analyzed. Raman peaks at v(SO42-), v(C-H) and v(O-H) modes were observed from the normal Raman and SERS measurements of laboratory-generated supermicron particles of ammonium sulfate (AS), AS mixed with succinic acid (AS/SA) and AS mixed with sucrose (AS/sucrose) particles. SERS measurements showed strong interaction between Ag nanoparticles and surface aqueous sulfate. Furthermore, SERS spectra of the solid AS and AS/SA particles revealed the presence of surface-adsorbed water (SAW) on their surfaces at 60% relative humidity. These observations suggest a possible role of SAW in facilitating the dissolution of sulfate from the bulk phase into its water layers. Submicron ambient particles exhibited non-enhanced features of black carbon and enhanced features of sulfate and organic matter, indicating an enrichment of sulfate and organic matter on the particle surface.