scholarly journals Supplementary material to "Electrospray-Surface Enhanced Raman Spectroscopy (ES-SERS) for probing surface chemical compositions of atmospherically relevant particles"

Author(s):  
Masao Gen ◽  
Chak K. Chan
2017 ◽  
Author(s):  
Masao Gen ◽  
Chak K. Chan

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.


2017 ◽  
Vol 17 (22) ◽  
pp. 14025-14037 ◽  
Author(s):  
Masao Gen ◽  
Chak K. Chan

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.


2019 ◽  
Vol 74 (3) ◽  
pp. 295-304
Author(s):  
Cecilia Baraldi ◽  
Maria Pamela Toti ◽  
Elsa Van Elslande ◽  
Philippe Walter ◽  
Maria Cristina Gamberini

Little is known concerning Phoenician and Punic cosmetics, and pertinent studies and analyses on archaeological finds are particularly scanty. The present study has taken into account 22 archaeological red and pink Punic make-up samples collected in several Sicilian museums. The samples were analyzed by infrared spectroscopy, Raman microscopy, and surface-enhanced Raman spectroscopy (SERS). The analyses revealed an interesting and unusual variability in the use of raw materials, ranging from the mineral to the organic world. Not only traditional dye-based pigments were identified, but also rare ones never reported previously for this use. We show also an occurrence unusual in antiquity of a lead chromate block presumably intended to be ground just before its use in cosmetics.


2017 ◽  
Author(s):  
Caitlin S. DeJong ◽  
David I. Wang ◽  
Aleksandr Polyakov ◽  
Anita Rogacs ◽  
Steven J. Simske ◽  
...  

Through the direct detection of bacterial volatile organic compounds (VOCs), via surface enhanced Raman spectroscopy (SERS), we report here a reconfigurable assay for the identification and monitoring of bacteria. We demonstrate differentiation between highly clinically relevant organisms: <i>Escherichia coli</i>, <i>Enterobacter cloacae</i>, and <i>Serratia marcescens</i>. This is the first differentiation of bacteria via SERS of bacterial VOC signatures. The assay also detected as few as 10 CFU/ml of <i>E. coli</i> in under 12 hrs, and detected <i>E. coli</i> from whole human blood and human urine in 16 hrs at clinically relevant concentrations of 10<sup>3</sup> CFU/ml and 10<sup>4</sup> CFU/ml, respectively. In addition, the recent emergence of portable Raman spectrometers uniquely allows SERS to bring VOC detection to point-of-care settings for diagnosing bacterial infections.


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