The rate constant k1 for reaction of CF3 with NO2 was investigated over the pressure range 1.5–110 Torr
Ar or N2 and at temperatures between 251 and 295 K. Time resolved emission from vibrationally excited CF2O and FNO products was used as a detection method for CF3 removal. The rate constant at room
temperature shows no marked variation with pressure, with an average value of k1
= (1.75 ± 0.26) × 10−11 cm3 molecule−1
s−1, where the errors are 2σ, but a small reduction at the lowest pressure indicates the possible
contribution from a third body recombination process. We conclude that this process is minor, and if it is treated as a separate reaction channel it results in a limiting high pressure branching ratio of 13 ± 7%, which drops to half that value at 10 Torr. As the limiting high and low pressure rate constants are within the 2σ error bars of k1, we recommend the average value as applying over the full pressure range. Combination with previous results shows that of the possible bimolecular channels, formation of CF2O + FNO dominates (ca. 95%).
No temperature dependence is seen, within experimental error. Pitfalls in the extraction of rate constants from
the analysis of time resolved product emission are discussed, and a method is described to assign rate
constants unambiguously to reactive formation and collisional quenching. CF3 radicals were formed from the 248 nm photolysis of CF3I, and observations of emission from the radical show previously unobserved
excitation in the asymmetric C–F stretching mode ν3.
在 1.5–110 Torr 压力范围内研究了
CF3 与
NO2 反应的速率常数 k1
Ar 或 N2,温度在 251 到 295 K 之间。振动激发的
CF2O 和 FNO 产物的时间分辨发射被用作 去除的检测方法。房间内的速率常数
温度随压力变化不明显,平均值为k1
= (1.75 ± 0.26) × 10−11 cm3 分子−1
s−1,其中误差为 2σ,但最低压力处的小幅减小表明可能的
来自第三体
重组过程的贡献。我们得出的结论是,这个过程很小,如果将其视为单独的反应通道,则会导致 13 ± 7% 的极限高压支化比,在 10 Torr 时降至该值的一半。由于限制高压速率常数和低压速率常数在 k1 的 2σ 误差条内,因此我们建议在整个压力范围内应用平均值。结合之前的结果表明,在可能的双分子通道中,
CF2O + FNO 的形成占主导地位(约 95%)。
在实验误差范围内,没有观察到温度依赖性。从中提取速率常数的陷阱
讨论了时间分辨产物排放的分析,并描述了分配速率的方法
明确反应形成和碰撞猝灭的常数。 自由基是由 I 的 248 nm 光解形成的,对自由基发射的观察表明以前未观察到
以不对称 C-F 拉伸模式 ν3 激发。