Surface induced dissociation of HD2+ – a non-statistical behavior in the H+ and D+ fragmentation channels

Surface induced dissociation (SID) of HD2+ upon impact on a Tore Supra tokamak graphite tile was studied in the collision energy range from 20 to 100 eV. SID of the projectile ion HD2+ on this graphite surface yields exclusively atomic fragment ions H+ and D+, whereas other possible fragment ions HD+ and D2+ were completely absent. In contrast to the statistical ratio of 2:1 of D:H in the HD2+ ion, the relative abundances of the measured H+ and D+ fragment ions were about of equal magnitude over the whole collision energy range studied. This non-statistical decay can be accounted for by vibrational predissociation through a minimal centrifugal barrier at a total angular momentum of about J∼27–30.