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Experimental and theoretical studies of the C2F4 + O reaction: Nonadiabatic reaction mechanism

dc.contributor.authorNguyen, T.L.
dc.contributor.authorDils, B.
dc.contributor.authorCarl, S.A.
dc.contributor.authorVereecken, L.
dc.contributor.authorPeeters, J.
dc.date2005
dc.date.accessioned2016-12-07T10:36:06Z
dc.date.available2016-12-07T10:36:06Z
dc.identifier.urihttps://orfeo.belnet.be/handle/internal/4636
dc.descriptionIn this work, the C2F4(X1Ag) + O(3P) reaction was investigated experimentally using molecular beam-threshold ionization mass spectrometry (MB-TIMS). The major primary products were observed to be CF2O (+ CF2) and CF 3 (+ CFO), with measured approximate yields of 84-11 +7% versus 16-7 +11%, respectively, neglecting minor products. Furthermore, the lowest-lying triplet and singlet potential energy surfaces for this reaction were constructed theoretically using B3LYP, G2M(UCC, MP2), CBS-QB3, and G3 methods in combination with various basis sets such as 6-31G(d), 6-31l+G(3df), and cc-pVDZ. The primary product distribution for the multiwell multichannel reaction was then determined by RRKM statistical rate theory and weak-collision master equation analysis. It was found that the observed production of CF3 (+ CFO) can only occur on the singlet surface, in parallel with formation of ca. 5 times more CF2O(X) + CF2(X1A1). This requires fast intersystem crossing (ISC) from the triplet to the singlet surface at a rate of ca. 4 × 1012 s-1. The theoretical calculations combined with the experimental results thus indicate that the yield of triplet CF 2(ã3B1 + CF2O formed on the triplet surface prior to ISC is ≤35%, whereas singlet CF2(X 1A1) + CF2O is produced with yield ≥60%, after ISC. In addition, the thermal rate coefficients k(O + C2F 4) in the T = 150-1500 K range were computed using multistate transition state theory and can be expressed as k(T) = 1.67 × 10 -16 × T1.48 cm3 molecule-1 s-1; they are in agreement with the available experimental results in the T = 298-500 K range.
dc.languageeng
dc.titleExperimental and theoretical studies of the C2F4 + O reaction: Nonadiabatic reaction mechanism
dc.typeArticle
dc.subject.frascatiChemical sciences
dc.audienceScientific
dc.subject.freeCarbon inorganic compounds
dc.subject.freeIonization
dc.subject.freeMass spectrometry
dc.subject.freeMolecular dynamics
dc.subject.freeOxygen
dc.subject.freePotential energy
dc.subject.freeStatistical methods
dc.subject.freeMolecular beam-threshold ionization mass spectrometry (MB-TIMS)
dc.subject.freeMultiwell multichannel reactions
dc.subject.freeNonadiabatic reaction mechanisms
dc.subject.freePotential energy surfaces
dc.subject.freeReaction kinetics
dc.source.titleJournal of Physical Chemistry A
dc.source.volume109
dc.source.issue43
dc.source.page9786-9794
Orfeo.peerreviewedYes
dc.identifier.doi10.1021/jp053585y
dc.identifier.scopus2-s2.0-27744566467


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