Electronic structure of tert-butyl halides and group 14 derivatives : electron affinities and dissociative electron attachment

Electron transmission (ET) and dissociative attachment (DA) spectroscopies are applied to the tert-butyl halides and to derivatives where the central carbon atom is replaced by a heavier group 14 element. In the tert-butyl halide series, the electron affinity increases with increasing size of the halogen atom, while in the group 14 analogues the electron affinity reaches a minimum value for the silicon derivatives. Bound-state and continuum multiple scattering Xα (MS-Xα) calculations reproduce very closely the energies of the resonances observed in the ET spectra. The DA spectra show that the ground anion state of the tert-butyl halides (except for the fluorine derivative) can decay following a dissociative channel, with halogen anion production. In the group 14 derivatives this mechanism is much less active. In some of the compounds investigated, dissociative capture of thermal electrons is also observed.