STATE-SELECTIVE ELECTRON-CAPTURE BY 18-KEV KR8-EXCITED RB-ASTERISK(15P-25P) RYDBERG ATOMS( IONS FROM LASER)

State-selective single electron capture, in collisions of multicharged ions Kr8+ at 18 keV with laser-excited Rydberg Rb(n(i)p) atoms, is i nvestigated by use of a field ionizing lens system (FILS), in a three- crossed-beam experiment. By scanning the laser over a wide range of wa velengths (303-298 nm), this investigation covers the 15p-25p Rydberg series, showing the influence of the initial state of Rb. For every we ll-defined Rb(n(i)p) state, (i) very high Rydberg states of the Kr7+* (n) product ions are detected as a consequence of the high degree of e xcitation of the target and of the high charge of the projectile, and (ii) the a distribution of the capture cross section is obtained in th e domain 67 less than or equal to n less than or equal to 95, by measu ring the energy spectrum of the Kr8+ ions produced by held ionization in the FILS of the excited product ions Kr7+. These n distributions b ecome wider and are systematically shifted towards higher a values as n(i) increases. By using the classical trajectory Monte Carlo method, the n distributions are calculated for the n(i)p series. Although the calculated a distributions are systematically wider, the behavior of t heir widths and of their relative positions is in agreement with the e xperiment. On the other hand, the extended classical over-the-barrier model yields a distributions significantly narrower than the experimen tal ones.