Energy pooling in Na $3p-\mathrm{N}\mathrm{a}$ $3p$ collisions

The formation of Na ($\mathrm{nl}$) and $\mathrm{Na}_2^{}{}_{}{}^{+}$ in sodium vapor (∼${10}^{13}$ ${\mathrm{cm}}^{-3\mathrm{}}$) irradiated by a single-frequency (20-MHz bandwidth) cw dye laser tuned to one of the $D$ lines has been studied. The dependence of product signal on laser power density suggests that Na $3p$-Na $3p$ energy pooling collisions are responsible for these species. Rate constants for specific reaction channels and temperature dependences of rate constants are also reported.