Total cross sections for dissociative electron attachment in dichloroalkanes and selected polychloroalkanes: The correlation with vertical attachment energies

Electron attachment into the lowest unoccupied molecular orbital of a typical polychloroalkane in the gas phase forms a temporary negative ion in which the impinging electron resides on a combination of local C-Cl sigma* orbitals. Because of the antibonding character of these orbitals, these anions may dissociate, producing Cl- with cross sections that vary enormously over the chloroalkane family. In this work, we present absolute total dissociative electron attachment (DEA) cross sections for 33 of these compounds, and we show that the peak values of the cross sections correlate strongly with the vertical attachment energies (VAEs) for formation of the lowest anion states at the equilibrium geometries of the neutral molecules. This behavior is a consequence of the remarkably monotonic dependence of the resonance widths of the temporary anion states on VAE over the range 0.42 < VAE < 3.45 eV. Finally, we note also the strong connection between the s-wave attachment process at 0 eV in these compounds and the VAEs associated with the nearby anion states. (C) 2000 American Institute of Physics. [S0021-9606(00)01128-4].