Sulfur K shell photo-fragmentation of CH3C(O)SH and CH3OC(O)SCl species

ERBEN, M. F; GERONES, M; ROMANO, R. M; DELLA VEDOVA, C. O

Campinas, Brasil

Otro; 18ª Reunião Anual de Usuários (RAU); 2008

There are reported scarce data related with absorption of x-ray photons for medium size molecules. Continuing our studies on -SCO- species, CH3OC(O)SCl and CH3C(O)SH molecules have been selected because complementary studies have been already conducted at the LNLS for these molecules [3], [4]. The aim of this work is to investigate the electronic properties of sulfur 1s core electrons and the dynamic of fragmentation followed by the photon absorption. Tunable synchrotron radiation at the soft X-Ray SXS beamline has been used to excite and ionized the sulfur 1s electrons. Total Ion Yield spectra and multi coincidence PEPICO and PEPIPICO spectra were acquired. Below the ionization threshold, the Total Ion Yield (TIY) spectra of thioacetic acid are dominated by an intense resonance near 2473 eV, with a less intense feature at 2476 eV. Comparing with previous spectra for related molecules, the former excitation could be associated to an electronic transitions to the vacant pi* orbital in the C(O)S group. This absorption is observed at 2472 eV for CH3OC(O)SCl. Fragmentation patterns from the PEPICO spectra denote the presence of simple, double and even triple ionized atomic fragments, which should be originated in fragmentation processes arising from multiply charged ion. Highly repulsive states should be populated in the absorption process. These states could dissociate by Coulombic explosion mechanism causing atomization processes as the leading fragmentation channels [5], [6]. PEPIPICO spectra are being analyzed in order to better understand these mechanisms.