Polarization-modulation infrared reflection-absorption spectroscopy (Pm-irras) is a sensitive tool for the analysis of species residing at gas-solid and gas-liquid interfaces. the polarization-modulation allows excellent back-ground compensation and the analysis of surface/interface species under moderate pressure (e.g. atmospheric pressure of ir-absorbing gases) is possible. we demonstrate a new possibility to extract simultaneously information of gas and solid phases in addition to surface species from the Pm-irras experiments, using co oxidation over Pt film as an example. modulation excitation spectroscopy (mes) has been combined with this technique to enhance the sensitivity and to analyze the kinetic behavior of species. the surface species involved in the oxidation process, the state of Pt, and the gas phase species (co and co2) could be simultaneously monitored in situ and analyzed quantitatively. the technique can serve as a valuable tool for investigations of various dynamic phenomena occurring at gas-solid interfaces.