THE FORMATION AND REACTIONS OF METASTABLE OXYGEN (¹Σ+g) MOLECULES

The intensity of the (0, 0) ( 1 Σ+ g ‐ 3 Σ ‐ g ) emission band of oxygen near 7600Å (which system is observed also in the night air‐glow) has been used to investigate the formation and removal of 0 2 ( 1 Σ+ g ) in the products of an r.f. discharge in dry oxygen at total pressures of 0.8–6 mm Hg and at 300†K. The concentration of O 2 ( 1 Σ+ g ) was found to be about 10 ‐4 mm Hg in a total pressure of 1 mm Hg. No change of concentration of O 2 ( 1 Σ+ g ) withtime, nor with oxygen atom concentration (for the same discharge conditions), could be observed. The results show that considerable amounts of metastable O 2 ( 1 Σ+ g ) molecules are formed within the discharge, and that virtually no formation of this species occurs by recombination of ground state oxygen atoms in the afterglow. 0 2 ( 1 Σ+ g ) may also be formed from other metastable species in the afterglow [such as O 2 ( l Δ g ], if the rates of production and removal of O 2 ( 1 Σ+ g ) are equal. Ozone removed O( 1 Σ+ g ), and simultaneously O( 3 P) atoms were formed, suggesting that the exothermic reaction 0 3 +0 2 ( 1 Σ+ g ) = 0( 3 P)+20 2 ( 3 Σ ‐ g ) is quite rapid.