Photodetachment ofO2−

The cross section for photodetachment of ${\mathrm{O}}_2^{-}$ has been measured for the range of photon energies 0.5 to 3.0 ev. No onset energy is discovered in this range but analysis of the data gives an extrapolated threshold at 0.15±0.05 ev. The curve is found to rise gradually with increasing slope, reaching a value of 2.4×${10}^{-18\mathrm{}}$ ${\mathrm{cm}}^2$ at 3.0 ev photon energy. Comparison of the data with the predictions of threshold law theory and the results of previous experiments results in an interpretation in terms of assumed potential curves for ${\mathrm{O}}_2^{-}$.