Fast heavy-ion induced desorption of biomolecules

Heavy ion beams with MeV energies from the Uppsala EN-tandem accelerator have been used to induce desorption of ions from samples of cesium iodide, ergosterol and glycylglycine. With a time-of-flight mass spectrometer the yield of secondary ions has been measured as a function of the velocity, atomic number, angle of incidence and charge-state of the primary ion. The results show that the desorption process is connected with the electronic part of the energy loss of the primary ion. The experimental data are discussed in terms of models based on a thermal spike or a Coulomb explosion in the track of the primary ion. (orig.)