Evaluation of the Difference in the Rate Coefficients of F₂ + NO_x (x = 1 or 2) → F + FNO_x by the Stereochemical Arrangement Using the Density Functional Theory

Abstract

The rate coefficient of F2 + NO → F + FNO is 2 to 5 orders of magnitude higher than that of F2 + NO2 → F + FNO2 even though bond energies of FNO and FNO2 only differ by ∼0.2 eV. To understand the cause of having different rate coefficients of these two reactions, the change in total energies was calculated by varying the stereochemical arrangement of F2 with respect to NOx (x = 1 or 2) by the density functional theory (DFT), using CAM-B3LYP/6-311 G+(d) in the Gaussian program. The permitted approaching angle between the x-axis and the plane consisting of O, N, F, and ϕ plays a key role to restrict the reaction of NO2 and F2 compared to the reaction of NO and F2. This restriction in the reaction space is considered to be the main cause of different rate coefficients depending on the selection of x = 1 or 2 of the reaction of F2 + NOx → F + FNOx, which was also confirmed by the difference in Si etch rate using the F formed by those reactions.

Gas-Phase Reaction between CF2O and CF3C(O)OH: Characterization of CF3C(O)OC(O)F

“…This E a is slightly lower than the E a for the heterogeneous thermal decomposition of CF 3 C­(O)­OH, and the value of the pre-exponential factor is consistent with a bimolecular homogeneous gas-phase reaction. − We can think the mechanism as a stepwise two-reaction mechanism from these reagents to produce CF 3 C­(O)­F, HF, and CO 2 …”