Atomic oxygen oscillator strengths in the autoionization region. I. The absolute strength of the 5s′ lines

A curve‐of‐growth method was used to determine the absolute oscillator strength and other line parameters of the autoionized transition $\mathrm{OI}{\text{:2s}}^2{\text{2p}}^4{}^3{P}_2{\text{→ 2s}}^2{\text{2p}}^3{(}^2{D}_{\text{5/2,3/2}}^0{\text{) 5s′\hspace{0.17em}}}^3{D}_{\text{3,2,1}}^0$ . This method was used because the spectral width of the lines is far less than the bandwidth of the spectrometer. Neither lifetime nor emission measurements are applicable because depopulation of the upper state occurs predominantly by autoionization. The atomic oxygen concentrations were detemined by means of the O–NO₂ titration. Sets of curves of growth were computed on the basis of the separation of the three levels, ${}^3{D}_{\text{3,2,1}}^0$ , as observed with a spectrograph, tabulated values of the relative line strengths based on L–S coupling, and consideration of the different broadening mechanisms operating under the conditions of the experiment. This included consideration of the configuration interaction of the upper states with the adjoining ionization continuum. Comparison of the experimental curve with the computed curves gives f = 0.0021, Σgf = 0.019, and Γ = 0.01 Å, resulting in an autoionization lifetime τ of 2 × 10⁻¹¹ sec.