Photodetachment Imaging Studies of the Electron Affinity of CF₃

Abstract

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 (Δ [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 (Δ [CF3 -] = −152.6 kcal/mol). We find the CBS-Q prediction of Δ [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.

Dissociative electron attachment to bromotrifluoromethane

“…2, this situation is shown in a schematic potential energy diagram of the ground state neutral CF 3 Br and the ground state anion along the C Br internuclear distance. Here the experimental adiabatic electron affinities for CF 3 Br (0.9 eV) [41], Br (3.36 eV) [43] and CF 3 (1.82 eV) [46] are used. The equilibrium C Br bond length 1.9Å for the neutral molecule and 2.7Å for the respective anion are adapted from reference [28] and the C Br bond dissociation energy (2.95 eV) from reference [42].…”

The vacuum-UV absorption spectrum of SF5CF3; implications for its lifetime in the earth’s atmosphere

“…[3]. Reference [24], and assuming the ionisation energy of CF 3 is 9.04 eV [25] and the electron affinity is 1.82 eV [26]. The values in brackets of column 1 are 0 K enthalpies of formation, in units of kJ mol -1 .…”

Chapter 3: Trifluoromethyl Sulphur Pentafluoride, SF5CF3: Atmospheric Chemistry and Its Environmental Importance via the Greenhouse Effect

“…The bottom half of Table 5 shows that whilst dissociation to neutral SF 5 and CF 3 is clearly energetically possible since the SF 5 −CF 3 bond strength is only 3.86 eV (Section 5.3), dissociation to the ion pair CF 3 + + SF 5 − (but not to SF 5 + + CF 3 − ) can also occur with 10.2 eV photon excitation. In determining the energetics of these reactions, we use values for the electron affinity of the CF 3 and SF 5 radicals of 1.82 and 3.8 eV, respectively [67,68]. Although the quantum yields for dissociation into ion pairs are generally unknown, their formation following VUV photoexcitation of polyatomic molecules should be prevalent, but this process for SF 5 CF 3 has not yet been observed.…”