Zeeman Effect and Line Breadth Studies of the Microwave Lines of Oxygen

Measurements made at 90°K and at 300°K on the ${\mathrm{O}}_2$ line breadths show that the line breadth parameter, $\Delta \nu$, varies as $T^{-x}$, with $x$ ranging in value from 0.76 for the $9_{-}$line to 0.90 for the $1_{-}$line. The type of variation of $x$ with the rotational quantum number $N$ indicates that both rotational resonance and quadrupole moment interactions are important factors in determining the line breadths. The Zeeman splittings observed for the $1_{-}$, the $1_{+}$, and the $3_{-}$ lines are in good agreement with the splitting predicted from first-order perturbation theory.