Irradiation of isolated collagen mimetic peptides by x rays and carbon ions at the Bragg-peak energy

We report on an experimental irradiation of isolated peptides by carbon ions at the Bragg-peak energy. Collagen mimetic peptides and their noncovalent complexes undergo nondissociative ionization, but also inter- and intramolecular fragmentation induced by internal energy transfer. We also detect nondissociative proton detachment, an ion-specific process. The average amount of energy transferred by ions is similar to the case of x-ray single photoabsorption, and our results indicate that it changes with the conformation and size of a given molecular system. Our work paves the way to experimental investigation of high-energy ion collisions involving proteins and DNA strands, to investigate the role of ion kinetic energy in internal energy deposition.