Infrared multiphoton excitation and dissociation studies of SO2

Infrared multiphoton absorption of 9 R(26) and 9 R(32) CO2 laser lines by SO2 molecule was studied for the unfocused laser energies of 100 mJ to 253 mJ. Dispersed fluorescence spectra extending from 3200 A to 4500 A confirmed the very strong coupling between the ground and excited electronic states of SO2. The shapes of the spectra were completely different for the 9 R(26) line or the neighboring 9 R(32) line corresponding to the wavelengths 1082.3 cm-1 and 1085.8 cm-1, respectively and for different laser energies. This indicates that the infrared multiphoton excitation process is controlled both by the laser intensity and the wavelength. The formation of sulfur from possible dissociation or fragmentation of SO2 molecules was monitored using glass substrates suspended inside the absorption cell. Proton-Induced X-ray Emission (PIXE) measurements of these substrates show the presence of sulfur only for the 9 R(32) laser line and energy of 253 mJ, providing evidence of fragmentation of SO2 under these conditions