Knowledge Bank

Relaxation of laser-excited $O2(A3\Sigma u+$, $v=6-10)$ in collisions with $O2$ populates high vibrational levels of $O2(b1\Sigma g+)$ and $O2(a1\Delta g)$. Previous work on the spectroscopy of $O2$ emissions from the Earth's night atmosphere has enabled us to assign the Q-branches of thirteen $(v\prime ,v\prime \prime )$ bands in the $(2+1)$ REMPI spectra of $O2(b1\Sigma g+$, $v\prime \prime =10-15)$ and $O2(a1\Delta g$, $v\prime \prime =16-19)$, through the intermediate Rydberg levels $3d\pi \mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma g+(v\prime =2-5)$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Delta =4,5)$, repectively. The derived spectroscopic constants for $O2(b1\Sigma g+,v\prime \prime =10-13)$ agree with our previous work. Improved values are obtained for $v\prime \prime =14,15$. Our constants for $3d\pi \mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma g+(v\prime \prime =5)$ are the first available. Our spectra are better calibrated and our constants for the $v\prime =2-4$ levels significantly more precise than the 1988-1992 work in the groups of Chupka and Houston. The energies of $O2(a1\Delta g,v\prime \prime =16-19)$ were known previously only to within about $80cm-1$ from the 1995 electron scattering work of Allan. The highest level known accurately from nightglow spectra is $v\prime \prime =11$. Our spectral analysis gives precise rotational constants and $\Delta G$ values for these vibrational levels and for $3d\pi \mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Delta g(v\prime =4,5)$. The absolute term energies are uncertain by about $5cm-1$ based on earlier work in the groups of Chupka and Houston. Supported by the NASA Geospace Sciences and Planetary Atmospheres programs and by the NSF Aeronomy and Physics/REU programs.