Fragmentation Mechanisms of Perfluorinated compounds using Synchrotron Radiation: Study of CF3CF2CF2C(O)Cl

YANINA BERRUETA MARTÍNEZ; REINALDO L. CAVASSO FILHO; CARLOS O. DELLA VÉDOVA; MAURICIO F. ERBEN; MARIANA GERONÉS; ANGÉLICA MORENO BETANCOURT; ROSANA M. ROMANO

Campinas

Otro; 23ª Reunião Anual de Usuários do LNLS/CNPEM; 2013

Laboratório Nacional de Luz Síncrotron

Perfluorinated compounds have been extensively used in industrial applicationsduring the last years. Recently, some perfluorinated species were detected in tissuesof animals, in environmental waters, and in the atmosphere. Different processesmay be responsible for the presence of these compounds in the environment. Forexample, the thermolysis of fluoropolymers and the degradation of fluorotelomeralcohols result in the emission of perfluorocarboxylic species to the atmosphere.In this work, and as part of a general project aimed to the elucidation of thephotofragmentation mechanisms of compounds relevant for atmospheric chemistry,we present the study of perfluorobutanoyl chloride using synchrotron radiation withenergies between 7.3 and 300 eV. The photoexcitation and photofragmentationmechanisms of perfluorobutanoyl chloride were studied in the TGM beamline atLNLS using the chamber for gaseous samples and coincidence techniques. There isno ion in the PEPICO spectra at energies lower than 11 eV, denoting that theseenergies are below the first ionization potential of the molecule. At 12 eV the onlyion in the spectrum is the ClCO+ fragment, while the increment of the excitationenergies leads to the formation of (M-Cl)+ and (M-ClCO)+. The CF3+ ion appears from 16 eV, becoming the most important fragment at higher energies. The TIYspectrum obtained around the Cl 2p threshold, 211 eV, shows three resonancespeaks at 201, 204 and 206 eV, while the C 1s TIY spectrum presents only oneresonance at 287 eV below the threshold, occurring at 296 eV. The PEPICO spectrain this energy region were found to be almost independent of the ionization energy,being the CF+ (the only CF species found so far in the interstellar medium),CF2+ and CF3+ fragments the most abundant of the spectra. The ions FCO+,CF2Cl+, C2F4Cl+, C3F6Cl+ and C3F7O+, also detected in the spectra, denotethe importance of frustrated dissociations to radicals followed by intramolecularabstraction reactions. Dissociation mechanisms were elucidated from PEPIPICOspectra.