NaHCO₃: A source of Na atoms for sudden sodium layers?

We consider the case of sudden sodium layers which have been reported in the lower E region of the ionosphere. We suggest that dissociative electron attachment to NaHCO 3 , NaHCO 3 + e → Na +HCO 3 − , can explain some of the observations, in particular at altitudes above 95 km. This process would produce Na efficiently only in the case where a plasma of high density is injected into the sodium layer. The rate constant for the reaction is estimated to be of the order of 10 −8 cm 3 s −1 by analogy with similar species and by derivation from the observed geophysical parameters.