This work presents the first direct experimental study on the thermal unimolecular decomposition of n-C 3 F 7 I. Experiments were performed behind incident and reflected shock waves using the atomic resonance absorption spectroscopy (ARAS) technique on a resonant line of atomic iodine at 183.04 nm. The reaction C 3 F 7 I + Ar → C 3 F 7 + I + Ar (1) was studied at specific temperature (800-1200 K) and pressure (0.6-8.3 bar) ranges. Under experimental conditions, the obtained values of the rate constant at temperatures below 950 K are close to the high-pressure limit; however, considering theoretical calculations, the influence of pressure on the rate constant at elevated temperatures remains noticeable. The resulting value of the experimental rate constant of reaction 1 is presented in the following Arrhenius form: 1st (±30%) = 1.05 × 10 14 exp(−200.4 kJ ⋅ mol −1 ∕ ) (s −1 ) Experimental data were found to correlate with the results of the Rice-Ramsperger-Kassel-Marcus -master equation analysis based on quantum-chemical calculations.The following low-and high-pressure limiting rate coefficients were obtained over the temperature range T = 300-3000 K: 0 ( −C 3 F 7 I + Ar ) = 8.849 × 10 19 −1.444 exp (−11, 454.4∕ ) (cm 3 mol −1 s −1 ) and ∞ ( −C 3 F 7 I ) = 9.676 × 10 16 −0.378 exp (−26, 956.8∕ ) (s −1 )with the center broadening factor F c = 0.119.
K E Y W O R D Satomic resonance absorption spectroscopy, chemical kinetics, density functional theory, dissociation rate constant, perfluoropropyl iodide, Rice-Ramsperger-Kassel-Marcus/master equation, shock tube 206