New Absorption Spectra of Atomic and Molecular Oxygen in the Vacuum Ultraviolet. I. Rydberg Series from O I Ground State and New Excited O2 Bands

Absorption series of ground‐state atomic oxygen (³P_2,1,0) and new O₂ bands in discharged He–O₂ mixtures have been observed in the 600–1000‐Å wavelength region. The O I spectrum consists of the nine allowed Rydberg series converging to the three lowest states of O II: ⁴S_3/2⁰, ²D_5/2,3/2⁰, and ²P_3/2,1/2⁰. The series observed were as follows: $$\begin{array}{c}{\text{2p}}^3{(}^4{S}^0{\mathrm{)ns\hspace{0.17em}}}^3{S}^0{\text{;\hspace{0.17em}2p}}^3{(}^4{S}^0{\mathrm{)nd\hspace{0.17em}}}^3{D}^0{\text{;\hspace{0.17em}2p}}^3{(}^2{D}^0{\mathrm{)ns}}^{\prime }{\hspace{0.17em}}^3{D}^0;\\ {\text{2p}}^3{(}^2{D}^0{\mathrm{)nd}}^{\prime }{\hspace{0.17em}}^3{S}^0{\text{;\hspace{0.17em}2p}}^3{(}^2{D}^0{\mathrm{)nd}}^{\prime }{\hspace{0.17em}}^3{P}^0{\text{;\hspace{0.17em}2p}}^3{(}^2{D}^0{\mathrm{)nd}}^{\prime }{\hspace{0.17em}}^3{D}^0;\\ {\text{2p}}^3{(}^2{P}^0{\mathrm{)ns}}^{\mathrm{\prime \prime }}{\hspace{0.17em}}^3{P}^0{\text{;\hspace{0.17em}2p}}^3{(}^2{P}^0{\mathrm{)nd}}^{\mathrm{\prime \prime }}{\hspace{0.17em}}^3{P}^0\mathrm{;\hspace{0.17em}}\mathrm{and}{\text{\hspace{0.17em}2p}}^3{(}^2{P}^0{\mathrm{)nd}}^{\mathrm{\prime \prime }}{\hspace{0.17em}}^3{D}^0.\end{array}$$ Measurement and classification of these lines are given. Most of the atomic‐energy levels involved were not previously known. The new O₂ bands are a progression of 10 members in the 835–900‐Å region. A definite assignment cannot be made at present, but the lower state is either the a ¹Δ_g or the b ¹Σ_g⁺ metastable state, with the former regarded as most likely. The spectra were observed both in a flowing microwave discharge and in the region downstream from this discharge.