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 N-2, O-2, H-2 and He has been investigated in a frequency range spanning from the millimeter-wave up to similar to 0.3 mm, at room temperature. In view of drawing conclusions over the J- and K-a-dependence trends of the pressure-broadening coefficients, for all perturbers, Q-type (Delta J = 0) transitions with 11 <= J <= 60 (with K-a = 10) and 0 <= K-a <= 6 (with J = 10) have been considered. While for all perturbers the observed trend suggests a weak maximum for J similar to 20, for the K-a dependence different trends are noted. For O-2, H-2, and He a small increase is noted by enlarging the K-a value, whereas a small decrease is observed for N-2. (C) 2012 Elsevier Ltd. All rights reserved.