Interpretation of the Atmospheric Absorption Bands of Oxygen

It is shown that the atmospheric oxygen absorption bands can be attributed to a ³S→¹S transition from the normal (³S) to a metastable ¹S excited state of O₂. This accounts for all the strong lines, and explains missing lines, without conflict with existing theory. Certain very weak series such as the A^' band are, however, not yet explained. Of the three rotational levels for each value of jₖ in the ³S normal state, the two for which j=jₖ±1 show only a very small separation, which increases slowly with jₖ, while the third is separated from the other two by an interval of about 2 wavenumbers which does not change with jₖ (cf. Fig. 2 and Table I). The ³S and ¹S states involved in the atmospheric bands may perhaps be attributed both to the same electron configuration, in agreement with a suggestion made in a previous paper. If this is the case, it is likely that a metastable ¹D state derived from the same configuration also exists, and that infra-red atmospheric bands corresponding to the transition ³S→¹D should be found.