Matrix photochemistry of organic sulfur-containing species with atmospheric interest

YANINA B. BAVA; A. LORENA PICONE; LUCIANA M. TAMONE; SAMANTHA SENG; YENY A. TOBÓN; SOPHIE SOBANSKA; ROSANA M. ROMANO

Biarritz

Conferencia; Chemistry and Physics at Low Temperatures 2016; 2016

Gaseous sulfur compounds are highly reactive and play an essential role in the formation of acid rain and the generation of atmospheric aerosols.[1,2] The sulfur-containing species evolves to different oxidation states. The most studied case is the oxidation of SO2 to SO42- to form secondary sulfated aerosols; however, other less-studied cases could occur, for example the oxidation of H2S, R-SH or R-S-R to SO2 and SO42-. Gases and particles interact with solar radiation in the atmosphere leading to a variation of the atmospheric composition. In fact, many studies show that atmospheric sulfur compounds produced by marine organisms (DMS, etc.) are transformed under the influence of solar radiation to form new products or secondary aerosols.[3-5] However, the information available on the photoreactivity of organic sulfur compounds including long chain and low volatile compounds is limited. In addition, photochemical mechanisms understanding of such processes are not very well known, due to the complexity of the systems and the short lifetime of the intermediate products.The IR matrix isolation spectroscopy is a very well suited technique for the study of photochemical mechanisms, due to the possibility of the detection of reactive intermediates, free radicals and molecular complexes. In this work, we will present the matrix isolated IR spectra of some organic sulfur containing species (e.g. CH3-OC(O)-CH2-SH, C2H5-C(O)S-CH2-CH=CH2, CH3-S-CH2-CH=CH2) as models of sulfur compound of industrial or biological origin, together with the photochemical studies using broad-band UV?visible radiation in the presence and absence of oxygen. A series of oxygen and sulfur containing compounds of atmospheric interest were formed during irradiation. In addition, sharpness of the IR absorptions, and particularly the behavior of the bands with the irradiation, allowed the assignment of the IR spectra and the proposition of reactional mechanisms. Indeed, we demonstrated that matrix isolation experiments are suitable to describe atmospheric processes.