Experimental and theoretical evidence for long-lived molecular hydrogen anions H2- and D2- -: art. no. 223003

The existence of (metastable) molecular hydrogen anions H-2(-), D-2(-), and H-3- 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 H-2(-) and D-2(-) of at least 3 mu s and 4 mu s, respectively, can be inferred. Theoretical calculations within the nonlocal resonance model predict the existence of highly rotationally excited anions with lifetimes in the mu s 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.