Release of diborane into the upper atmosphere

Diborane (DB) has been released in twilight and produced brilliant greenish trails and puffs in the 90- to 150-km altitude region. The emission was identified as the fluorescent solar scattering by BO2 molecules. No chemiluminescence was observed, contrary to expectations from laboratory studies. The absence of chemiluminescence limits the use of DB as an atmospheric tracer to dawn and dusk periods. The radial spread of the gaseous DB releases was more confined than that of the liquid trimethylaluminum (TMA) releases; thus improved triangulation was possible.