Observations of Diatomic and Triatomic Hydrogen Negative Ions

Mass-spectrometric observations have been made of HD^-, D₂^-, H₃^-, H₂{D}^{{-}}$, H${D}₂^{{-}}$, and ${D}₃^{{-}}$, using a hollow-cathode duoplasmatron negative-ion source operating between 0.1 and 2 Torr. Both the diatomic and triatomic hydrogen negative ions appear stable, with half-lives greater than ${10}^{{-}5}$ sec. Attenuation-cross-section measurements of ${D}₂^{{-}}$ and ${D}₃^{{-}}with helium between 3 and 5 keV yield average values of (5.5 and 7.0) ×{10}^{{-}15}$ ${cm}²$, respectively.