Photodetachment imaging studies of the electron affinity of CF₃

The photoelectron spectra of the trifluoromethyl anion, CF₃^-, at 355 and 258 nm are reported. Simulation of the partially resolved vibrational structure is used to extract the adiabatic electron affinity, AEA[CF₃] = 1.82 ± 0.05 eV. The heat of formation for the trifluoromethyl anion derived from the adiabatic electron affinity (ΔH_f,298⁰[CF₃^-] = -153.4 ±1.5 kcal/mol) is compared to the high-accuracy "isodesmic bond additivity corrected" (BAC) complete basis set (CBS-Q) theory prediction (ΔH_f,298⁰[CF₃^-] = -152.6 kcal/mol). We find the CBS-Q prediction of ΔH_f,298⁰[CF₃] = -112.1 kcal/mol, after BAC, to be in excellent agreement with the most recent experimental determination of the radical heat of formation. The photoelectron angular distribution at 355 nm was also extracted from the photoelectron image, revealing p wave photodetachment with an energy-averaged anisotropy parameter of β= 1.5 ± 0.1.