Photoionization dynamic of O-methyl dithiocarbonate (dimethyl xanthate), CH3OC(S)SCH3, on the sulfur 2p absorption edge

MAURICIO F. ERBEN; ANTONELA CANNEVA; LUCAS S. RODRÍGUEZ PIRANI; REINALDO L. CAVASSO FILHO; ROSANA M. ROMANO; CARLOS O. DELLA VÉDOVA

Campinas

Otro; 25th RAU Annual Users Meeting LNLS; 2015

Laboratório Nacional de Luz Síncrotron

Xanthates (from the Greek ?golden?) are the esters of xanthic acid, with general formula ROC(S)SR'. These are important organosulfur compounds used in the production of cellophane and as flotation agents for extraction of metals from many ores. As an example, sodium ethyl xanthate is added as a collector in the selective flotation of PbS (galena) to separate it from ZnS (sphalerite). A series of xanthate and xanthogen derivatives are being the subject of investigation in our group, including synthetic aspects together with the elucidation of structural, conformational and vibrational properties.1 Following our general project aimed at elucidating the shallow and inner?shell core electronic properties and photoionization dynamics of sulfur-containing derivatives,2,3 we became now interested in the simplest xanthate compound, with R=R´=CH3. Here we report a study of the photon impact excitation and dissociation dynamics of CH3OC(S)SCH3 exited at the S 2p level by using synchrotron radiation. Interestingly, the photoelectron spectrum of CH3OC(S)SCH3 in the valence region (7.5-13 eV energy range) was reported by Guimon et al. in 1974 and interpreted in terms of ionization of non-bonded orbital mostly localized on the sulfur atoms. 4 The S 2p core XPS and KLL Auger spectra of CH3OC(S)SCH3 were early reported by Suoninen et al. 5 showing that the ionization energies of the =S and ?S? atoms within the xanthate group differ from each other by 1.5 eV, this difference assigned to the initial-state charge distribution rather than to final-state relaxation. In this presentation, the TIY spectra of CH3OC(S)SCH3 following S 2p excitations is reported and compared with the previous data. The dissociative photoionizaiton is discussed in term of PEPICO and PEPIPICO spectra and possible fragmentations mechanisms are deduced from the interpretation of the PEPIPICO spectra. Thus, the advantage of energy tunability offered by synchrotron radiation allowed us for a clear understanding of the resonant electronic processes occurring after excitation of each of the sulfur atoms present in this molecule and how the ionic dissociation is affected.