Investigation of positron scattering from atomic fluorine and fluorine-containing molecules

Abstract

We report positron scattering cross sections of fluorine and fluorine-containing molecules across an energy range from 1 to 5000 eV. Targets considered in the present study are F, F₂, HF, CF₄, C₂F₆, C₆F₆, CHF₃, C₂H₃F₃, and C₂H₂F₂. Elastic, inelastic, total, and positronium formation cross sections were calculated using the optical potential approach, and the ionisation cross sections are estimated employing the complex scattering potential-ionisation contribution method. The computed results are in satisfactory agreement with available theoretical data. Comparison with experiments shows excellent agreement in the high-energy range; however, discrepancies are observed at lower energies, attributed to deficiencies in the polarisation potential model used and, in part, to the difficulty in resolving forward-angle scattering effects in experimental measurements. Positron interactions with these molecules are important in plasma, astrophysics, and radiation physics, where ionisation, energy losses, and the formation and destruction of positronium are significant. The positron scattering cross-sections are primary inputs for modelling in astrophysics, materials science, and medical imaging, such as positron emission tomography.