  The onset of collision dynamics between an ion and a Rydberg atom is studied
in a regime characterized by a multitude of collision channels. These channels
arise from coupling between a non-polar Rydberg state and numerous highly polar
Stark states. The interaction potentials formed by the polar Stark states show
a substantial difference in spatial gradient compared to the non-polar state
leading to a separation of collisional timescales, which is observed in situ.
For collision energies in the range of $k_\textrm{B}\cdot\mu$K to
$k_\textrm{B}\cdot$K, the dynamics exhibit a counter-intuitive dependence on
temperature, resulting in faster collision dynamics for cold - initially "slow"
- systems. Dipole selection rules enable us to prepare the collision pair on
the non-polar potential in a highly controlled manner, which determines
occupation of the collision channels. The experimental observations are
supported by semi-classical simulations, which model the pair state evolution
and provide evidence for tunable non-adiabatic dynamics.
