Measurement of the Submillimeter-Wave Rotational Transition of Oxygen at 424 kMc/sec

The submillimeter-wave rotational transition $N=1\mathrm{}\to 3$, $J=2\mathrm{}\to 2$ of oxygen has been measured at a frequency of 424 763.80 ± 0.20 Mc/sec. The millimeter-wave fine-structure frequencies for the $N=1\mathrm{}$ and $N=3\mathrm{}$ states have been remeasured with high precision. From the results the rotational constant of oxygen $B_0=43\mathrm{}100.589\pm 0.022$ Mc/sec has been derived.