  It is often stated that heavy-ion nucleon knockout reactions are mostly
sensitive to the tails of the bound-state wavefunctions. In contrast, (p,2p)
and (p,pn) reactions are known to access information on the full overlap
functions within the nucleus. We analyze the oxygen isotopic chain and explore
the differences between single-particle wave functions generated with potential
models, used in the experimental analysis of knockout reactions, and ab initio
computations from self-consistent Green's function theory. Contrary to the
common belief, we find that not only the tail of the overlap functions, but
also their internal part are assessed in both reaction mechanisms, which are
crucial to yield accurately determined spectroscopic information.
