Mechanism of sputtering of large biomolecular ions by impact of highly ionizing particles

We describe a model for the ejection of large biomolecules from surfaces by impact of high-energy (1 MeV/nucleon) heavy ions. The model involves the rapid vibrational excitation of the biomolecule by low-energy electron irradiation arising from the incident particle track. The excitation breaks most hydrogen bonds binding the molecule to the surface and causes the molecule to expand on a subpicosecond timescale; the expanding molecule pushes against the substrate and generates sufficient momentum to escape.