Positronium Scattering by CO and LiF*

Experimental measurements of the total cross section for scattering of Positronium (Ps) by various atomic and molecular targets are very similar to electron scattering cross sections above the Ps ionization threshold [1].  Using a Free Electron Gas model [2] we have previously calculated elastic scattering cross sections for Ps scattering by the homonuclear diatomic molecules N₂ and O₂ as well as CO₂ [3]. To obtain the total scattering cross section we added the Ps ionization cross section which was computed using the binary encounter method. Our calculations confirmed that the total cross section for electron and Ps scattering is similar above the Ps ionization threshold. In the present work we extend our calculations to include the heteronuclear diatomics CO and LiF. For CO we again see a similarity between the electron and Ps cross sections. While there are no experimental results for either molecule in the gas phase there are experimental results for Ps scattering by a LiF surface [4]. Our Ps-LiF ionization cross sections may help with the interpretation of these results.

¹S. J. Brawley et al., Science 330, 789 (2010).  ²R. S. Wilde and I. I. Fabrikant, Phys. Rev. A  98, 042703 (2018).  ³R. S. Wilde, H. B. Ambalapitiya and I. I. Fabrikant, Phys. Rev. A 104, 012810 (2021). ⁴M. H. Weber et al., Phys. Rev. Lett. 61, 2542 (1988).