Monitoring adsorbed species during oscillatory reactions using vibrational spectroscopy

We describe here a simple real-time experimental method for measuring infrared reflection-absorption spectra of adsorbed species during an oscillatory heterogeneous reaction. The method is applicable to any reproducibly reversible system and involves adding interferograms taken at equivalent points in an oscillatory cycle. In a first application it has been used to determine the phase relationship of the C-O and N-O absorption bands in the NO + CO reaction on Pt(100) and relate them to the partial pressures of the reactants and products.