CENTRO DE QUIMICA INORGANICA "DR. PEDRO J. AYMONINO"
Unidad Ejecutora - UE
congresos y reuniones científicas
Dissociation mechanisms of SO2- containing molecules after photoexcitation with synchrotron radiation in the energy range between 100 and 1000 eV
ANGÉLICA MORENO BETANCOURT; YANINA B. BAVA; REINALDO L. CAVASSO FILHO; CARLOS O. DELLA VÉDOVA; MAURICIO F. ERBEN; MARIANA GERONÉS; ROSANA M. ROMANO
Otro; 23ª Reunião Anual de Usuários do LNLS/CNPEM; 2013
Laboratório Nacional de Luz Síncrotron
Recent investigations in our research group have been dedicated to the elucidationof photochemical reaction mechanisms between small molecules that are relevantas atmospheric contaminants or components. For example the photochemicalgas-phase reaction between SO2, O2 and Cl2 was studied and the reaction mechanismswere proposed on the basis of the isolation and identification of the products.Molecules of the type ClSO2(OSO2)nCl, with n=1,2 and the novel peroxideClSO2OOSO2Cl were determined, among others, as the main photoproducts. Onthe frame of a general project aimed to the elucidation of the photochemical andelectronic properties of molecules containing the XSO2- group, with X=halogen, wepresent here the study of the of the ionic photofragmentation of three compoundsof this family: (ClSO2)2O, FSO2NCO and ClSO2NCO, after core-shell excitationof C 1s, N 1s, O 1s, and F 1s electrons. Photoionization and photofragmentationof the compounds in the energy region between 250 and 1000 eV were studiedin the SGM beamline at LNLS, using the experimental station for gaseous samplesand coincidence techniques. The detection of ionic fragments in coincidence,PEPIPICO techniques, allows the study of unimolecular photofragmentation mechanisms.At the high excitation energies, the most important processes conduct usuallyto atomic fragments produced through concerted mechanisms. Nevertheless,in the three molecules studied here several polyatomic ionic fragments were detectedin coincidence. The NCO+/SO+ coincidence was observed for FSO2NCOand interpreted as a four-body secondary decay after differed charge separationmechanisms. It is worth to mention that this coincidence was not observed inthe case of ClSO2NCO, for which most of the fragmentation mechanisms involveatomic fragments. On the other hand, the SO2+ ion was produced from (ClSO2)2Oby several different mechanisms.