PROJECTILE VELOCITY DEPENDENCE OF EMISSION-LINE POLARIZATION DEGREES FOLLOWING SLOW AR8-LI(2S) STATE-SELECTIVE ELECTRON-CAPTURE COLLISIONS()

The influence of the projectile velocity on the m(l) distributions of the Ar7+ excited states produced by electron capture during Ar8+-Li(2s ) collisions is studied experimentally between 1.5 and 4.5 keV amu(-1) by measuring the polarization of the emitted light, and theoretically between 1 and 4 keV amu(-1) by using the classical trajectory Monte C arlo (CTMC) method. We investigate the 7l'-8l and 8l'-9l radiative tra nsitions subsequent to the decay of the 8l and 9l sublevels of Ar VIII , which are preferentially populated by the single electron capture pr ocess. A small but not negligible effect is seen for the experimental polarization ratios relating to transitions from sublevels of large l values, showing a slight increase of the component parallel to the inc ident ion beam as the projectile energy increases. Theoretical polariz ation ratios obtained from CTMC calculated m(l) distributions are in e xcellent agreement with the measured polarization ratios. Electronic e nergy curve calculations are then presented in order to discuss these results in terms of dynamical couplings.