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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/acp-2017-361
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
08 May 2017
Review status
This discussion paper is a preprint. A revision of the manuscript was accepted for the journal Atmospheric Chemistry and Physics (ACP).
Electrospray-Surface Enhanced Raman Spectroscopy (ES-SERS) for probing surface chemical compositions of atmospherically relevant particles
Masao Gen and Chak K. Chan School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue, 6 Kowloon, Hong Kong, China
Abstract. We present electrospray-surface enhanced Raman spectroscopy (ES-SERS) as a new approach to measuring the surface chemical compositions of atmospherically relevant particles. The surface-sensitive SERS is realized by electrospraying Ag nanoparticle aerosols over analyte particles. Spectral features 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). SERS measurements showed strong interaction (or chemisorption) between Ag nanoparticles and surface aqueous sulfate [SO42−] with [SO42−]AS/sucrose > [SO42−]AS/SA > [SO42−]AS. Enhanced spectra of the solid AS and AS/SA particles revealed the formation of surface-adsorbed water on their surfaces at 60 % relative humidity. These observations of surface aqueous sulfate and adsorbed water demonstrate a possible role of surface-adsorbed water in facilitating the dissolution of sulfate from the bulk phase into its water layer(s). Submicron ambient aerosol particles collected in Hong Kong exhibited non-enhanced features of black carbon and enhanced features of sulfate and organic matter (carbonyl group), indicating an enrichment of sulfate and organic matter on the particle surface.

Citation: Gen, M. and Chan, C. K.: Electrospray-Surface Enhanced Raman Spectroscopy (ES-SERS) for probing surface chemical compositions of atmospherically relevant particles, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2017-361, in review, 2017.
Masao Gen and Chak K. Chan
Masao Gen and Chak K. Chan
Masao Gen and Chak K. Chan

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Short summary
We propose electrospray-surface enhanced Raman spectroscopy (ES-SERS) for measuring the surface chemical compositions of atmospherically relevant particles. The observations of surface aqueous sulfate and adsorbed water demonstrate a possible role of the water in facilitating the dissolution of sulfate from the bulk phase into its water layers. ES-SERS of submicron ambient aerosol particles collected in Hong Kong indicated an enrichment of sulfate and organic matter on the particle surface.
We propose electrospray-surface enhanced Raman spectroscopy (ES-SERS) for measuring the surface...
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