Knowledge Bank

High resolution $(0.002cm-1)$ stimulated Raman $spectra1$ of the fundamental vibrational band of $02$ have been recorded at room temperature and, using a pulsed free-expansion $jet2$, at 50k. These spectra include the normal Q-branch and the satellite Q-branches at $1554cm-1$ and $1558cm-1$ that arise due to the splitting of the $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}\Sigma g$ ground state of molecular oxygen by spin-spin and spin-rotation interactions. Both satellite Q-branches were completely resolved for the first time. Measured intensity ratios for the $\Delta N\Delta J(J.N)=Q0(2,1)$ and lines, and for the and lines compare favorably with that for a coupling case intermediate between Hund's Cases (a) and (b). Depolarization ratios, measured for a series of $QQ$-branch (unresolved) triplets. give a value $0.164\pm 0.004$ for the depolarization ratio of the fundamental vibrational band.