Dissociation dynamics of FCO and HCO radicals

摘要

Dissociation energies and barriers to dissociation for XCOrarr;X+CO have been calculated forXtilde;thinsp;2Arsquo;andAtilde;thinsp;2pgr; states of FCO and HCO byabinitiomolecular orbital methods. At the PUMP4sol;sol;UMP2/6hyphen;311Gast; level,Dcir;298(Fhyphen;CO)=22.3 kcalthinsp;molminus;1and Dgr;H298=24.2 kcalthinsp;molminus;1for dissociation of groundhyphen;state FCO; these values are much higher than the corresponding bond energy and activation enthalpy for HCO dissociation. Calculated RRKM rate constants suggests that the lifetime of FCO under stratospheric conditions is sufficient to allow bimolecular reactions to compete with dissociation. Reaction with O2may provide aninsitusource of stratospheric CO2.