Energy selective excision of CN− following electron attachment to hexafluoroacetone azine ((CF3)2CN–NC(CF3)2)

Abstract

Low energy electron attachment (DEA) to hexafluoroacetone azine (HFAA) leads to a remarkable energy selective excision of CN⁻ within a pronounced resonance located at 1.35 eV. The underlying dissociative electron attachment (DEA) reaction involves multiple bond cleavages and rearrangement within the neutral products. A series of further fragment ions (F⁻, CF₃⁻, (CF₃)₂C⁻ and (CF₃)₂CN⁻) are observed from resonant features above 2 eV and only (CF₃)₂CN⁻ is additionally formed within a narrow resonance below 1 eV. In contrast to CN⁻ all the remaining fragment ions can be formed by simple bond cleavages with (CF₃)₂CN⁻ being the result of a symmetric decomposition of the target molecule by cleavage of the (N–N) bond with the excess charge localised on either of the identical fragments. Our ab initio calculations predict an adiabatic electron affinity of HFAA close to 2 eV with the geometry of the relaxed anion considerably distorted with respect to that of the neutral molecule.