Experimental and theoretical evidence for long-lived molecular hydrogen anions H2- and D2

The existence of (metastable) molecular hydrogen anions H2-, D2-, and H3- is demonstrated. These anion species were produced by sputtering of TiH2 and TiD2 targets with Cs+ ions and were identified by accelerator mass spectrometry. From the respective flight times through the spectrometer, lifetimes for H2- and D2- of at least 3μs and 4μs, respectively, can be inferred. Theoretical calculations within the nonlocal resonance model predict the existence of highly rotationally excited anions with lifetimes in the μs range. It is proposed that in sputtering molecular hydrogen species with high rotational and vibrational excitation are formed that are stable on the time scale of the experiment.