Nonlocal complex potential theory of dissociative electron attachment: Inclusion of two vibrational modes

Abstract

The process of dissociative electron attachment (DEA) to molecules with several vibrational degrees of freedom is usually treated in the approximation of the local potential for the description of the nuclear motion. We develop the nonlocal complex potential theory to treat the dissociation dynamics when there is more than one vibrational mode in the neutral molecule. We demonstrate the application of the multimode nonlocal theory to a generic molecule of the type $\mathrm{C}{Y}_{3}X$, where Y denotes the H or F atom and X denotes the halogen atom, with the inclusion of symmetric C--X stretch and $\mathrm{C}{Y}_{3}$ deform (``umbrella'') vibrational modes. We present results for the dependence of DEA cross sections on the electron energy and vibrational energy for the ${\mathrm{CF}}_{3}\mathrm{Cl}$ molecule in the two-mode approximation. The 1.5 eV peak in the DEA cross section is well described in the one-mode approximation. However, inclusion of additional modes is required to explain the experimentally observed low-energy peak in the DEA cross section at the vibrational temperature ${T}_{v}=800$ K.