CENTRO DE QUIMICA INORGANICA "DR. PEDRO J. AYMONINO"
Unidad Ejecutora - UE
congresos y reuniones científicas
HeI Photoelectron and Valence Synchrotron Photoionization Studies of CClH2SCN
MAURICIO F. ERBEN; LUCAS RODRÍGUEZ PIRANI; MARIANA GERONÉS; ROSANA M. ROMANO; REINALDO L. CAVASSO FILHO; CARLOS O. DELLA VÉDOVA
Congreso; XIX Reuniao Anual de Usuários (RAU),; 2009
Laboratório Nacional Luz Síncrotron
Organosulfur compounds have attracted much attention and several outstanding reviews covering the chemistry of thiocyanates (RSCN) and isothiocyanates (RNCS) can be found in the chemical literature.1-3 Simple alkylated species, (R= alkyl), are very well known molecules. For example, methyl isothiocyanate, CH3NCS, is widely used as an agricultural fumigant and much attention in recent years has been devoted to understand the effect of this application on the atmospheric balance.4 Recently, we became interested in the CH3SCN molecule, in particular the inner shell electronic properties and the ionic fragmentation of photon excited CH3SCN following S 2p excitation were studied by using synchrotron radiation.5 The dynamic of the ionic fragmentation of S 2p excited CH3SCN is dominated by the rupture of both carbon-sulfur bonds, a process that may be related with electronic excitations from the ground electronic state to vacant ó* molecular orbitals. The recent development of a neon gas filter in the TGM line at the Brazilian Synchrotron National Laboratory (LNLS) now affords pure synchrotron radiation in the 12-21.5 eV range, and this has permitted us to enlarge the study of photoionization processes into the valence region. The coalition of PES and multicoincidence Time-Of-Flight (TOF)-based techniques seems to offer a most promising approach to a deeper understanding of the electronic structure and the ionic dissociation induced by photon absorption in the valence region. Following this methodology, relatively simple species such as XC(O)SCl (X= F and Cl) and CH3C(O)SCH3 have been studied.6,7 For the later, vibronic structure was observed in the valence synchrotron photoionization process. Here we report a study of the photon impact excitation and ionization dissociation dynamics of CClH2SCN, in a combined approach that includes the use of HeI photoelectron spectroscopy and of photoionization under the action of synchrotron radiation in the valence region. Total and partial ion yields have been measured, together with the PEPICO spectra at selected photon energies, thereby allowing the study of the dissociation dynamics of excited CClH2SCN molecules.