Surface–Bulk Correlation Spectroscopy for the Characterization of Ternary Adsorption

A method is proposed whereby the range of equilibrium constants that describe how a ternary mixture of molecules is adsorbed onto a solid substrate may be obtained. This information may then be related to the surface preference of a particular species. The technique utilizes infrared and/or Raman spectra of the bulk phase, together with sum frequency generation spectra of the surface in a heterospectral two-dimensional correlation analysis. The method consists of a series of up to three experiments in which the bulk concentrations are varied, followed by a set of rules for interpreting the resulting correlation maps to identify adsorption sequences and surface preference. A scheme is provided to direct the design of the experiments and analyses for such multi-component mixtures.