Cross section calculations for electron scattering from DNA and RNA bases

Area of Science:

• Atomic and Molecular Physics
• Chemical Physics
• Biophysics

Background:

• Understanding electron interactions with DNA and RNA bases is crucial for radiobiology and radiation chemistry.
• Previous theoretical and experimental data for elastic electron scattering from these biomolecules are scarce.

Purpose of the Study:

• To calculate differential and integral cross sections for elastic electron collisions with key DNA and RNA bases.
• To compute total cross sections for single electron-impact ionization of these bases.
• To investigate the relationship between cross sections and molecular properties like symmetry, electron count, and size.

Main Methods:

• Independent Atom Method (IAM) with a static-polarization model potential for elastic scattering (50–4000 eV).
• Binary-Encounter-Bethe (BEB) model for electron-impact ionization (ionization threshold–5000 eV).
• Comparison of calculated ionization cross sections with existing theoretical formalisms.

Main Results:

• Calculated cross sections for elastic and ionization processes show dependence on molecular symmetry, electron number, and size.
• Guanine and adenine exhibit the highest elastic and ionization cross sections.
• Uracil displays the lowest cross sections for both elastic scattering and ionization.

Conclusions:

• The study provides valuable theoretical cross-section data for electron interactions with DNA and RNA bases.
• The findings highlight the varying efficiencies of elastic and ionization processes among different bases.
• The theoretical approach's validity is supported by comparisons with similar molecules, given the lack of direct experimental data.