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The cross-section ratios R of transfer ionization to single electron capture of Helium atom induced by fluorine ions in the strong-interaction region were measured by means of the position-sensitive-detection and the time-of-flight (TOF) technologies. The velocity and charge state dependence of R were studied. It is found that the R decreases when the 2q/v increases, where q and v are the charge state and velocity of projectile respectively. In this energy region the transfer ionization can be look as Two-Step process that one target electron is captured, and another electron is ionized.

The ratios of the cross section of the transfer-ionization to the single-electroncapture of Argon induced by C q+ (q = 1, 2, 3) ions are measured by means of position sensitive and time-of-flight techniques. Our experimental results are compared with the data of He q+ (q = 1, 2) − Ar of DuBois. A qualitative interpretation is presented based on the Classical-Over-Barrier Model of Bohr.ion-atom collision, transfer-ionization, single-electron-capture, over barrier model Investigation of highly charged ions collision with atoms is one of the hot points in the field of atom/molecule, especially from the low to an intermediate energy range. We report measurements cross section of the transfer-ionization to the single-electron-capture ratios R, and the projectile energy varies from 0.2 MeV to 6.35 MeV. These investigations are needed in many applications like astrophysics, plasma physics and so on. The process of a projectile A q+ in collisions with an atom B can be expressed as:where the projectile ion A q+ finally captures k electron(s) and changes its charge state to ( ) A , q k − + which is called scattered projectile ion. The target atom B loses r electron(s) and becomes ionized; B r + is the recoil ion. Finally (r − k) electrons are emitted from the collision process. When (r − k) > 0, the reaction is called transfer-ionization (TI) process, and several different mechanisms can contribute to it. In this process, there are two main mechanisms: Shake-Off process and Two-Step process. When the projectile velocity is faster, and reaction time with target atoms is shorter, the probability of capture electron will be smaller. The main reaction channel is direct-single-ionization, and direct-two-ionization of target atoms works because of the Shake-Off process. When the projectile velocity becomes slow, the reaction time will increase, and two or more target atoms reacting with the projectile ion would be ionized, which is called Two-Step process [1,2] . In fact, these two

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