Autodetachment of Diatomic Carbon Anions from Long-Lived High-Rotation Quartet States

We show that strong molecular rotation drastically modifies the autodetachment of C−2 ions in the lowest quartet electronic state 𝑎⁢4Σ+𝑢. In the strong-rotation regime, levels of this state only decay by a process termed “rotationally assisted” autodetachment, whose theoretical description is worked out based on the nonlocal resonance model. For autodetachment linked with the exchange of six rotational quanta, the results reproduce a prominent, hitherto unexplained electron emission signal with a mean decay time near 3 ms, observed on stored C−2 ions from a hot ion source.