CENTRO DE QUIMICA INORGANICA "DR. PEDRO J. AYMONINO"
Unidad Ejecutora - UE
congresos y reuniones científicas
Photochemistry of individual particles: Evidence of sulfate formation through oxidation of organic sulfur compounds on particle surface
A. L. PICONE, R. M. ROMANO; S. SENG, Y. TOBÓN, M. MOREAU, S. SOBANSKA; R. CIURARU, C. GEORGE
Congreso; Pacifichem 2015; 2015
Reactivity of atmospheric aerosols at the individual particle scale is still sparsely studied whereas the climate and health impacts of aerosols depend also on their spatially resolved heterogeneous chemistry. The development of levitation systems coupled with Raman microspectrometry(RMS) allows to investigate the physical and chemical transformations of individual particles in conditions reproducing atmospheric environment. Such experimental devices aremainly used for investigating the hygroscopic properties of particles. Surprisingly, any studies devoted to the (photo)reactivity of individual particles are reported whereas using environmental cells allows appropriate investigations for (photo)-transformation of organic-containing particles.In this work, we have investigated the (photo)-reactivity of individual particles composed of organic sulfur compounds (CH3CO2CH2SH, MTG) as a model of low volatile species. The photo-reactivity process of single particles was performed using an acoustic levitation system coupled with RMS. Individual levitated particles were irradiated with UV-Vis light and the processes taking place in the condensed phase were followed by RMS. The morphological changes, chemical and phase transformations as well as internal structure of the particle were investigated and will be discussed in the presentation. Results clearly evidenced the surface and heterogeneous processes of the MTG droplet oxidation into S8and SO42- together with a particle size reduction and amorphous state. Complementary, gas phase studies supported the formation of secondary sulfated compounds which is of atmospheric interest.