N2-, O2-, H2-, and He-broadening of SO2 rotational lines in the mm-/submm-wave and THz frequency regions: The J and Ka dependence

The collisional broadening of several rotational lines of SO2 perturbed by N2, O2, H2 and He has been investigated in a frequency range spanning from the millimeter-wave up to ∼0.3mm, at room temperature. In view of drawing conclusions over the J- and Ka-dependence trends of the pressure-broadening coefficients, for all perturbers, Q-type (ΔJ=0) transitions with 11≤J≤60 (with Ka=10) and 0≤Ka≤6 (with J=10) have been considered. While for all perturbers the observed trend suggests a weak maximum for J∼20, for the Ka dependence different trends are noted. For O2, H2, and He a small increase is noted by enlarging the Ka value, whereas a small decrease is observed for N2.

► N2-, O2-, H2-, and He-broadening of pure rotational lines of SO2 in the vibrational ground state. ► Wide frequency range: from millimeter-wave up to the THz frequency region. ► J and Ka dependence of the pressure-broadening coefficients.