The relative abundances of metastable H*3 and D 3* molecules in collimated beams of neutralized ions are analyzed by the technique of collisional reionization (charge stripping). The fraction of metastable/dissociative species formed in the electron transfer process H3+ (D3+)+K(g) →H*3(D*3)+K+ diminishes if the precursor ions have excess internal energy. The abundance ratio of H*3/D*3 for equivalent 6 keV beam fluxes increases sharply when the time span between neutralization and reionization is increased. The measurements show that a state of D*3 with low rotational quantum numbers (N>0) is decaying on the time scale of the beam transit with a lifetime of about 0.2 μs. Results are interpreted in reference to the predissociation behavior of the 2p 2A″2 electronic state of the radical. The disproportionate ratio of IH *3/ID*3 ≫ 1 is a consequenceof the relative abundances of precursor levels in H3+ and D 3+ that can transform into metastables by electron transfer.