COLD-TARGET RECOIL-ION-MOMENTUM SPECTROSCOPY STUDY OF SINGLE-ELECTRONCAPTURE FROM HE BY SLOW AR8+ IONS

Cold-target recoil-ion-momentum spectroscopy (COLTRIMS) has been used to study single electron capture from He by Ar8+ ions at projectile ve locities between 0.2 and 1.0 a.u. Populations of 3d through 7l states on the final ion are resolved, and angular distributions are presented for separated major final channels. As the projectile velocity is rai sed, the reaction window is observed to spread. Contrary to expectatio ns based on a Landau-Zener picture of the process, higher n and I beco me favored with higher v. The results are in excellent agreement with coupled-channel calculations.