Metastable states of diatomic hydrogen anions

Transient states of the negative hydrogen molecule H−2 have drawn attention as intermediate reaction complexes in important molecular reactions like associative detachment (AD: H− + H → H−2→ H−2 + e−) and dissociative attachment (DA: e− + H2 → H−2 → H + H−). Recently it has been shown that metastable states of hydrogen molecular anions exist that defy both auto detachment and spontaneous dissociation for several microseconds (in the case of H−2) and even milliseconds (in the case of D−2). Here we present Coulomb explosion measurements for H−2 and D−2 that provide detailed information on the shape of the molecular wave function. We compare these experimental results with calculated wave functions obtained using a nonlocal resonance model. Our measurements confirm the predicted stabilization of H−2 and D−2 in states of high angular momentum