Knockout driven fragmentation of porphyrins

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.