Hyperfine structure and isotope shift in the far-infrared ground-state transitions of atomic oxygen

We have investigated the ³{P}₂→³{P}₁$ and $³P₁{{→}}³P₀ atomic fine-structure transitions in isotopically enriched samples of oxygen by means of tunable far-infrared spectroscopy. Accurate frequency measurements (a few parts in 10⁸) were made for all three stable isotopes and the ¹⁷O hyperfine structure was resolved. The experimental values for the isotopic shift of ¹⁸O relative to ¹⁶O for the J=2{→}J=1 and J=1{→}J=0 fine-structure transitions are in agreement with theoretical calculations.