Theoretical ionization and capture cross sections for DNA nucleobases impacted by light ions

Area of Science:

• Atomic and Molecular Physics
• Chemical Physics
• Radiation Biology

Background:

• DNA lesions are critical for cellular survival post-irradiation but are understudied experimentally and theoretically.
• Understanding proton interactions with DNA bases is essential for radiobiology and radiation protection.

Purpose of the Study:

• To develop and compare theoretical models for predicting single ionization and single capture total cross sections of DNA bases impacted by protons.
• To investigate the behavior of these cross sections across a range of proton impact energies.

Main Methods:

• Classical Trajectory Monte Carlo (CTMC) model.
• Quantum mechanical models: Coulomb Born (CB1) and Continuum-Distorted Wave Eikonal-Initial-State (CDW-EIS).
• Calculation of total cross sections for proton interactions with adenine, cytosine, thymine, and guanine.

Main Results:

• Proton-induced ionization and capture cross sections were calculated for DNA bases.
• Agreement between CTMC, CB1, and CDW-EIS models was observed at high impact velocities.
• Discrepancies among models were noted at low impact energies (below 100 keV).

Conclusions:

• Theoretical models provide insights into proton-DNA base interactions, particularly at higher energies.
• Existing theoretical cross sections tend to underestimate experimental data for adenine and thymine.
• A reasonable agreement was found between theoretical predictions and experimental data for cytosine.