Dynamics of l‑Phenylalanine Sputtering by Argon Cluster Bombardment

We simulate the impact of an Ar1000 cluster (energy 10 keV, impact angle 55°) into an amorphous l-phenylalanine target. By use of a ReaxFF potential, it is possible to model not only the emission dynamics of intact Phe molecules but also the fragmentation and reaction pathways taken. The simulated sputter yield is in close agreement with experiment. The simulated emission mass spectrum features both emission of large Phe n clusters and entrainment of reaction products in the ejected flow, again in agreement with experimental observation. While H abstraction is a common fragmentation channel, the H radicals quickly combine with Phe in the amino group; no isolated H atom is ejected.