Pollutant trapping studies. 2 —Spontaneous and resonance Raman studies of the surface reaction of sulphur dioxide on zeolites

Raman spectra of SO 2 adsorbed on zeolites X, Y and A are reported together with a normal coordinate analysis of the various spectra of the adsorbed molecuar SO 2 . The data indicate that crystal‐like SO 2 is adsorbed on cation sites II and III of the zeolitic oxide framework. Internal SO 2 force constants quantifying adsorbate distortion are developed and compared with the frequency difference parameter,Δ(ν 3 –ν 1 ). Raman spectral data also indicate the formation of several decomposition products of SO 2 , generated by surface reactions, which may include S   3 − , S 2 , S 4 , S x O, SO   3 2−and SO   4 2− . Of these the lines attributed to S   3 − , S 2 , S 4 and S x O exhibit resonance enhancement.