The surface reaction of SO2 with adsorbed NO−3 on Ag metal microstructures: A surface enhanced Raman scattering experiment

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Abstract
Surface enhanced Raman scattering has been used in conjunction with mass spectrometry to study the in situ replacement reaction of adsorbed NO−3 on Ag metal powder with SO2 gas to form adsorbed SO=3 and SO=4 and gaseous NO2. Analysis of the intensity changes of the observed peaks lead to a model for surface reaction at low coverage. The time dependent background intensity, proportional to the adatom concentration which changes during the chemical reaction, is used to normalize the surface enhanced Raman scattering (SERS) peaks intensities. The resulting spectrum is proportional to the time dependent coverage and, if the reaction heat is small, the time independent electromagnetic enhancement. Examples are given demonstrating this effect.