Existence of H2−, a relatively long-lived doubly charged negative atomic hydrogen ion

Doubly charged negative hydrogen ions H2− and D2− have been indirectly observed in a tandem mass spectrometer using a hollow cathode duoplasmatron ion source. The half-life of these doubly charged ions, determined in a number of drift time experiments, is 23±4 nsec. The existence of these ions is concluded from a velocity, momentum, and energy analysis of hydride ions produced in the autodetachment process: X2−→X−+e (X=H,D).