Laser Magnetic Resonance of theO2Molecule Using the 337- μm HCN Laser

We observed thirteen laser magnetic resonance lines (transitions between $\mathrm{}[n=3,J=4\mathrm{}]\mathrm{}\to \mathrm{}[n=5,J=5\mathrm{}]\mathrm{}$ for the oxygen molecule, using the 337-μm line of the HCN laser. The magnetic $g$ factors ($g_{\perp }=2.0044\mathrm{}$, $g_z=2.0020\mathrm{}$, and $g_n=0.000\mathrm{}125$) give the best fit to the data. The zero-field frequency for the transition $\mathrm{}(N=J=3\mathrm{})\mathrm{}\to \mathrm{}(N=J=5\mathrm{})\mathrm{}$ obtained by using these sets of the magnetic $g$ factors all agree with theoretical value of 775.700 43 ±0.000 01 GHz if an experimental uncertainty of ± 1 G (± ${10}^{-4\mathrm{}}$ T) is allowed.