Trajectory dependent charge-state distribution of planar channeled heavy ions

The exit charge state and exit angle distribution of 103.5 MeV oxygen ions transmitted through a 1 μm thick Si single crystal was measured as a function of the incident charge state and incident angle with respect to the (110) planar channeling direction. The aim of the present measurement was to investigate the dependence of electron loss and electron capture probabilities on the impact parameter. The conservation rule of the transverse energy allows us to determine the channeling trajectory of the ion from its incident and exit angles. A series of exit charge state and scattering angle distributions, Y(θ_sc,q_ex;θ_in,q_in,t), were measured by scanning the incident angle, θ_in, with a step of 0.01° for incident charge states of q_in = 6, 7 and 8 at path lengths of t = 9500 and 10500 Å. Two parameter mappings of the yields as functions of θ_in and θ_sc clearly show characteristic features reflecting the combination of q_in and q_ex, which enabled us to deduce impact-parameter dependent electron transfer cross sections with an aid of a Monte Carlo simulation.