Scattering and recoiling imaging spectrometry in the blocking configuration is used to obtain a three-dimensional ion fraction map of 5 keV He + scattered from a Si(100)-(2x1)-two domain surface. The scattered ion fractions Y are highly sensitive to the alignment of the He + beam with the crystal geometry, with Y varying from a minimum of 2% to a maximum of 10%. Scattering and recoiling imaging code simulations, including Auger-neutralization and charge exchange in the close collision, show that the highest Y values correspond to ions that collide with Si atoms in the outermost surface layers. The experimentally measured fraction of He + surviving as ions from the surface layers are as follows: Y 1 s t ~70%, Y 2 n d ~25%, and Y 3 r d ~5%. After fitting the experimental charge fraction with the two adjustable parameters v 0 (characteristic velocity) and P c (charge exchange probability in the close collision) for three blocking exit angles of 35 o , 45 o , and 55 o , good agreement between experiment and simulation was found for v 0 =(1.9+/-0.1)x10 7 cm/s and P c =0.34+/-0.09.