Fragmentation of multiply ionized biomolecules induced by MeV heavy ions

Collision-induced ionization and fragmentation of gas-phase adenine molecules (C₅N₅H₅) have been investigated for single electron capture collisions of 1.2 MeV C²⁺ ions. Coincidence measurements between the number of ejected electrons and the time-of-flight of fragment ions allows us to determine charge states of intermediate parent ions r. Highly charged parent ions are observed up to r ∼ 6 and the production of lighter fragment ions becomes predominant with increasing r. We found that kinetic energies of H⁺ are significantly larger than those of other fragment ions and become nearly equivalent irrespective of r for r > 1. (paper)