Doubly charged clusters - neutral atom charge transfer: the role of the Coulombic repulsion

We have studied experimentally the collisional charge transfer between a neutral atom and a multicharged metal-atom cluster. The charge transfer cross section measured for Na 31+ + + Cs is in the range of 400 A2. The time-of-flight mass analysis of the singly charged collision products demonstrates that an energy of about 0.5 eV is deposited in the cluster fragment during the charge transfer collision. This effect can be interpreted as a charge transfer to an excited state of the metal cluster. The measured cross section for Na 31+ + + Cs is larger than the one for Na 31+ + Cs collisions. This difference between these two systems is due to the existence, for the first one, of a Coulombic repulsion term in the collision output channel.