  It was first noted during the 1970s that finite-range distorted wave Born
approximation (FR-DWBA) calculations were unable satisfactorily to describe the
shape of the angular distributions of many single-proton (and some
single-neutron) transfer reactions induced by heavy ions, with calculations
shifted to larger angles by up to ~ 4 degrees compared with the data. These
reactions exhibited a significant mismatch, either of the reaction Q value or
the grazing angular momentum of the entrance and exit channels, and it was
speculated that the inclusion of multi-step transfer paths via excited state(s)
of the projectile and/or ejectile could compensate for the effect of this
mismatch and yield good descriptions of the data by shifting the calculated
peaks to smaller angles. However, to date this has not been explicitly
demonstrated for many reactions. In this work we show that inclusion of the
two-step transfer path via the 4.44-MeV 2+ excited state of the 12C projectile
in coupled channel Born approximation calculations enables a good description
of the 208Pb(12C,11B)209Bi single-proton stripping data at four incident
energies which could not be described by the FR-DWBA. We also show that
inclusion of a similar reaction path for the 208Pb(12C,13C)207Pb single-neutron
pickup reaction has a relatively minor influence, slightly improving the
already good description obtained with the FR-DWBA.
