Electron affinity of trans-2-C4F8 from electron attachment-detachment kinetics.

Electron attachment and detachment kinetics of 2-C(4)F(8) were studied over the temperature range 298-487 K with a flowing-afterglow Langmuir-probe apparatus. Only parent anions were formed in the attachment process throughout this temperature range. At the highest temperatures, thermal electron detachment of the parent anions is important. Analysis of the 2-C(4)F(8) gas showed an 82/18 mixture of trans/cis isomers. The kinetic data at the higher temperatures were used to determine the electron affinity EA(trans-2-C(4)F(8)) = 0.79 +/- 0.06 eV after making some reasonable assumptions. The same quantity was calculated using the G3(MP2) compound method, yielding 0.74 eV. The kinetic data were not sufficient to establish a reliable value for EA(cis-2-C(4)F(8)), but G3(MP2) calculations give a value 0.017 eV greater than that for trans-2-C(4)F(8). MP2 and density functional theory were used to study the structural properties of the neutral and anion isomers.