Elastic scattering of electrons fromF2: AnR-matrix calculation

The $R$-matrix method for electron-molecule scattering developed by one of us (B.I.S.) is applied to the elastic scattering of electrons from ${\mathrm{F}}_2$ in the static-exchange approximation. Calculations are presented using both ${\mathrm{F}}_2$ and ${\mathrm{F}}_2^{-}$ core orbitals to construct the electron-molecule interaction potential. The total and differential elastic scattering cross sections are quite different for the two molecular fields and can be interpreted in terms of the presence or absence of an ${\mathrm{F}}_2^{-}$ bound negative ion at the equilibrium internuclear separation in ${\mathrm{F}}_2$. Since there is little experimental data on ${\mathrm{F}}_2^{-}$ or $e+{\mathrm{F}}_2$ collisions, the calculations coupled with some detailed electron-beam experiments would be of great value in furthering our understanding of the chemistry of ${\mathrm{F}}_2^{-}$.