  We have studied collisions between tetraphenylporphyrin cations and He or Ne
at center-of-mass energies in the 50-110 eV range. The experimental results
were interpreted in view of Density Functional Theory calculations of
dissociation energies and classical Molecular Dynamics simulations of how the
molecules respond to He/Ne impact. We demonstrate that prompt atom knockout
strongly contributes to the total destruction cross sections. Such impulse
driven processes typically yield highly reactive fragments and are expected to
be important for collisions with any molecular system in this collision energy
range, but have earlier been very difficult to isolate for biomolecules.
