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The time of flight mass spectrometry method is used to study processes occurring when 36 keV multiply charged Ar ions (Ar 6+ ) capture electrons from adenine and uracyl molecules. Adenine and uracyl constitute one of two base pairs entering into the RNA composition. The fragmentation scheme of resulting molecular ions is derived by analyzing correlations between the detection times of all fragment ions. Frag mentation patterns for molecular ions resulting from molecule ionization by photons, electrons, protons, and multiply charged ions are compared.

Time-of-flight (TOF) techniques have been used to measure singly and multiply ionized Ar recoils in coincidence with energy-analysed, forward-ejected electrons in 1 MeV H + -Ar collisions. Electron energies up to 2800 eV and charge states 1-4 are covered. It is shown experimentally that the peak of binary-encounter (BE) electrons in the electron energy spectrum is associated almost entirely with single ionization of Ar, whereas the peak of electron-captureto-the continuum (ECC) electrons is associated with multiple ionization. This shows that the BE electrons originate exclusively from the valence shell of Ar (the M shell) and the ECC electrons predominantly from an inner shell (the L shell).