Experimental investigation of electron and positron interactions with monosubstituted and disubstituted benzene derivatives: fluorobenzene, 1, 3-difluorobenzene and 1, 4-difluorobenzene molecules

Abstract

Electron and positron scattering from fluorobenzene (C6H5F), 1, 3-difluorobenzene (1, 3-C6H4F2) and 1, 4-difluorobenzene (1, 4-C6H4F2) molecules have been investigated experimentally using the linear transmission time-of-flight method. Total cross sections (TCSs) were measured and determined for 0.8–600 eV and 0.7–600 eV, respectively, for electron and positron scattering from 1, 3-C6H4F2 and 1, 4-C6H4F2 molecules, and 0.4–1000 eV and 0.2–1000 eV, respectively, for electron and positron scattering from C6H5F molecules. A broad resonance structure has been observed in the C6H5F electron TCSs at 0.8–1.6 eV, corresponding to the 1.6 eV 2E2u C6H6 resonance structure. This broad structure seems to be made of two structures at 0.8 eV and 1.4 eV, which should mean that the original single 1.6 eV resonance peak in the C6H6 parent molecule has split into two upon the monosubstitution of its H atom by the F atom. 1, 3-C6H4F2 electron TCSs show a rising trend below 2 eV, a feature attributed to the polar nature of these molecules. Above 4 eV for all these three molecules, electron TCSs are greater than positron TCSs by a factor of ∼2 at energies up to 40 eV.