Revisiting spontaneous Raman scattering for direct oxygen atom quantification

摘要: In this Letter, the counterintuitive and largely unknown Raman activity of oxygen atoms is evaluated for its capacity to determine absolute densities in gases with significant O-density. The study involves ${\rm CO}_2$ microwave plasma generate a self-calibrating mixture establish accurate cross sections $^3{\!P_2}{\leftrightarrow ^3}{\!P_1}$ ^3}{\!P_0}$ transitions. approach requires conservation stoichiometry, confirmed within experimental uncertainty by 1D fluid model. measurements yield ${\sigma _{J = 2 \to 1}} 5.27 \pm _{{\rm sys}:0.53}^{{\rm rand}:0.17} \times {10^{- 31}}\;{{\rm cm}^2}/{\rm sr}$ 0}} 2.11 sys}:0.21}^{{\rm rand}:0.06} sr}$, detection limit estimated be $1 {10^{15}}\;{{\rm cm}^{- 3}}$ systems without other scattering species.