화학공학소재연구정보센터
Journal of Physical Chemistry, Vol.99, No.48, 17394-17402, 1995
Kinetics of the Reaction of Cf3O with No
The reaction between CF3O and NO has been studied by laser flash photolysis/transient diode laser absorption over the range 213 K less than or equal to T less than or equal to 353 K. CF3O was generated by the 193 nm photolysis of(CF3O)(2). The dominant dissociation pathway is O-O bond fission (Phi congruent to 0.85), but C-O bond breaking occurs to a small extent (Phi congruent to 0.15). A significant fraction of the CF3O (similar to 30%) is born with sufficient internal excitation to dissociate into F2CO and F atoms. The presence of NO leads to additional F2CO formation. The analysis of this formation rate, as well as the NO loss rate, yields a temperature dependent rate constant of (4.4 +/- 1.5) x 10(-11)e((+100+/-88)/T) cm(3) s(-1) for the CF3O + NO reaction. The measured rate constants agree well with previous results based on observations of CF3O disappearance. They confirm expectations that the reaction yields exclusively the products FNO and F2CO and that it serves as an efficient stratospheric sink for the CF3O radical. The reaction between CF3O and HCl has also been examined, and an upper limit of 2 x 10(-13) cm(3) s(-1) has been determined for its rate constant at 295 K. The small rate constant for this reaction relative to the rapid removal of CF3O by NO severely limits the possibility that hydrofluorocarbons contribute to stratospheric ozone depletion by their CF3O degradation product liberating chlorine atoms from HCl.