CONICET | Buscador de Institutos y Recursos Humanos

present work, we investigate the ionization of molecules of biological interest by theimpact of multicharged ions in the intermediate to high energy range. We performed full nonperturbativedistorted-wave calculations (CDW) for thirty-six collisional systems composed bysix atomic targets: H, C, N, O, F, and S?which are the constituents of most of the DNA andbiological molecules?and six charged projectiles (antiprotons, H, He, B, C, and O). On accountof the radiation damage caused by secondary electrons, we inspect the energy and angulardistributions of the emitted electrons from the atomic targets. We examine seventeen molecules:DNA and RNA bases, DNA backbone, pyrimidines, tetrahydrofuran (THF), and CnHncompounds. We show that the simple stoichiometric model (SSM), which approximates themolecular ionization cross sections as a linear combination of the atomic ones, gives reasonablygood results for complex molecules. We also inspect the extensively used Toburen scaling of thetotal ionization cross sections of molecules with the number of weakly bound electrons. Basedon the atomic CDW results, we propose new active electron numbers, which leads to a betteruniversal scaling for all the targets and ions studied here in the intermediate to the high energyregion. The new scaling describes well the available experimental data for proton impact,including small molecules. We perform full molecular calculations for five nucleobases and testa modified stoichiometric formula based on the Mulliken charge of the composite atoms. Thedifference introduced by the new stoichiometric formula is less than 3%, which indicates thereliability of the SSM to deal with this type of molecules. The results of the extensive ion-targetexamination included in the present study allow us to assert that the SSM and the CDW-basedscaling will be useful tools in this area.