Isotope effects on the populations of metastable H3 and D3 molecules in neutralized ion beams

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Abstract
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 H+3(D+3)+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 2A2 electronic state of the radical. The disproportionate ratio of IH*3/ID*3 ≫ 1 is a consequence of the relative abundances of precursor levels in H+3 and D+3 that can transform into metastables by electron transfer.