Sulphur dioxide is most noteworthy as an environmental pollutant. Interaction of a free electron laser beam of wavelength 4 μm with rotational lines of sulphur dioxide is studied. Values of transmittance, averaged over intervals of 0.1 cm-1, are obtained for absorber thickness 0.01, 0.1 and 1 atm-cm, using the quasi-random model of molecular band absorption. From these values, intensities of the high resolution absorption lines of SO2 are simulated in the frequency interval 2463.4983– 2464.919 cm-1. The experimental data taken for this work agree well with the result. There is clearly a scope to apply this work in atmospheric optics.
