We model the nucleosynthesis during a radiative interpulse phase of a rotating 3 { { M } _ { \odot } } Asymptotic Giant Branch ( AGB ) star .
We find an enhanced production of the neutron source species { { } ^ { 13 } { \mathrm { C } } } compared to non-rotating models due to shear mixing of protons and { { } ^ { 12 } { \mathrm { C } } } at the core-envelope interface .
We estimate that the resulting total production of heavy elements by slow neutron capture ( s -process ) is too low to account for most observations .
This due to the fact that rotationally induced mixing during the interpulse phase causes a pollution of the { { } ^ { 13 } { \mathrm { C } } } pocket layer with the neutron poison { { } ^ { 14 } { \mathrm { N } } } .
As a result we find a maximum neutron exposure of \tau _ { \mathrm { max } } = 0.04 { \mathrm { mbarn ^ { -1 } } } in the s -process layer of our solar metallicity model with rotation .
This is about a factor of 5 \dots 10 less than required to reproduce the observed stellar s -process abundance patterns .
We compare our results with models that include hydrodynamic overshooting mixing , and with simple parametric models including the combined effects of overshooting and mixing in the interpulse .
Within the parametric model a range of mixing efficiencies during the interpulse phase correlates with a spread in the s -process-efficiency .
Such a spread is observed in AGB and post-AGB stars as well as in pre-solar SiC grains .