ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
The reaction F+O2+M→FOO+M(1) in the bath gases M=He, Ar, and N2 was studied by time-resolved uv absorption spectroscopy of the FOO radical at 220 nm. The experiments were performed at total pressures between 1 and 1000 bar and temperatures between 100 and 420 K. The absorption cross section of FOO was determined as σ (300 K)=1.6⋅10−17 cm21 at 220 nm. The F–O2 bond energy was derived by third law analysis of the equilibrium constant K1=9.15⋅10−24⋅T−0.45⋅exp(5990 K/T) cm3 (between 315 and 420 K) for reaction (1), being (49.8±1) kJ mol−1 (at 0 K). Limiting low pressure rate constants for the recombination reaction (1) of k1,0/[He]=3.7⋅10−33⋅(T/300 K)−1.1 cm6 s−1, k1,0/[Ar]=4.4⋅10−33⋅(T/300 K)−1.4 cm6 s−1, and k1,0/[N2]=5.8⋅10−33⋅(T/300 K)−1.7 cm6 s−1 were obtained between 100 and 373 K. The transition to a high pressure plateau of the rate constants was observed in all cases although the transition to diffusion-controlled reaction may have been superimposed at very high pressures. Correcting for this effect, a limiting high pressure rate constant of k1,∞=1.2⋅10−10 cm3 s−1 was derived between 100 and 373 K. In addition, a rate constant for the reaction F+FOO→F2+O2(2) of k2=1.4⋅10−9 exp(−2790 K/T) cm3 s−1 (340–420 K) with an uncertainty of Δk2/k2=±10% was derived. Furthermore, an equilibrium constant for the reaction F+FOO↔F2O2(3) of K3=(1.9±0.7)⋅10−15 cm3 was obtained at 340 K. © 1995 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.469258
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