Electron capture and ionization cross-section calculations for proton collisions from methane and the DNA and RNA nucleobases

Abstract

Net ionization and net capture cross-section calculations are presented for proton collisions from methane molecules and the DNA/RNA nucleobases adenine, cytosine, guanine, thymine, and uracil. We use the recently introduced independent-atom-model pixel counting method to calculate these cross sections in the 10 keV to 10 MeV impact energy range and compare them with results obtained from the simpler additivity rule, a previously used complete-neglect-of-differential-overlap method, and with experimental data and previous calculations where available. It is found that all theoretical results agree reasonably well at high energies, but deviate significantly in the low-to-intermediate energy range. In particular, the pixel counting method which takes the geometrical overlap of atomic cross sections into account is the only calculation that is able to describe the measurements for capture in proton-methane collisions down to 10 keV impact energy. For the nucleobases it also yields a significantly smaller cross section in this region than the other models. New measurements are urgently required to test this prediction.

References in corpus (2)

• A screened independent atom model for the description of ion collisions from atomic and molecular clusters
• Proton-impact-induced electron emission from biologically relevant molecules studied with a screened independent atom model

Cited by in corpus (3)

• Non-perturbative scaling behavior for net ionization of biologically relevant molecules by multiply-charged heavy-ion impact
• Independent atom model description of multiple ionization of water, methane, and ammonia molecules by proton impact
• A generalized independent atom model approach for net ionization of molecules by multiply-charged heavy-ion impact