Photodegradation of methyl thioglycolate particles as a proxy for organosulphur containing droplets

Understanding the formation and transformation of sulphur-rich particles is of prime importance since they contribute to the global atmospheric sulphur budget. In this work, we performed a series of experiments on a photoactive organosulphur compound namely, methyl thioglycolate, as a model of an organosulphur species of marine origin. By investigating the photoproducts within levitated droplets, we showed that elemental sulphur (α-S8) and sulphate (SO4 2-) can be photochemically generated at the gas-liquid interface by heterogeneous interaction with gaseous O2 and H2O. These results demonstrate that the surface of levitated droplets facilitate the oxidation of methyl thioglycolate in the dark, while illumination is necessary to produce the oxidation in bulk experiments.Fil: Seng, Samantha. Universite Des Sciences Et Technologies de Lille;Fil: Picone, A. Lorena. Facultad de Ciencias Exactas, Universidad Nacional de la Plata; ArgentinaFil: Bava, Yanina B.. Facultad de Ciencias Exactas, Universidad Nacional de la Plata; ArgentinaFil: Juncal, Luciana C.. Facultad de Ciencias Exactas, Universidad Nacional de la Plata; ArgentinaFil: Moreau, Myriam. Universite Des Sciences Et Technologies de Lille;Fil: Ciuraru, Raluca. Universite Des Sciences Et Technologies de Lille;Fil: George, Christian. Universite Claude Bernard Lyon 1;Fil: Romano, Rosana M.. Universite Claude Bernard Lyon 1;Fil: Sobanska, Sophie. Facultad de Ciencias Exactas, Universidad Nacional de la Plata; ArgentinaFil: Tobon, Yeny A.. Universite Des Sciences Et Technologies de Lille

Photodegradation of methyl thioglycolate particles as a proxy for organosulphur containing droplets

Understanding the formation and transformation of sulphur-rich particles is of prime importance since they contribute to the global atmospheric sulphur budget. In this work, we performed a series of experiments on a photoactive organosulphur compound namely, methyl thioglycolate, as a model of an organosulphur species of marine origin. By investigating the photoproducts within levitated droplets, we showed that elemental sulphur (α-S8) and sulphate (SO4 2-) can be photochemically generated at the gas-liquid interface by heterogeneous interaction with gaseous O2 and H2O. These results demonstrate that the surface of levitated droplets facilitate the oxidation of methyl thioglycolate in the dark, while illumination is necessary to produce the oxidation in bulk experiments.Centro de Química Inorgánic

Photodegradation of methyl thioglycolate particles as a proxy for organosulphur containing droplets

Understanding the formation and transformation of sulphur-rich particles is of prime importance since they contribute to the global atmospheric sulphur budget. In this work, we performed a series of experiments on a photoactive organosulphur compound namely, methyl thioglycolate, as a model of an organosulphur species of marine origin. By investigating the photoproducts within levitated droplets, we showed that elemental sulphur (α-S8) and sulphate (SO4 2-) can be photochemically generated at the gas-liquid interface by heterogeneous interaction with gaseous O2 and H2O. These results demonstrate that the surface of levitated droplets facilitate the oxidation of methyl thioglycolate in the dark, while illumination is necessary to produce the oxidation in bulk experiments.Centro de Química Inorgánic

Photoswitching of the spin crossover polymeric material [Fe(Htrz)₂(trz)](BF₄) under continuous laser irradiation in a Raman scattering experiment

Photoswitching of the [Fe(Htrz)2(trz)](BF4) spin crossover polymeric material has been investigated by means of confocal Raman spectroscopy upon continuous laser irradiation outside and inside its thermal hysteresis loop. In both cases, the evolution of HS and LS Raman marker bands show that light excitation can trigger the LS to HS transition, but the long-lived HS state can be populated only within the hysteresis loop. Local sample heating can explain this light-induced effect leading to a narrowing of the thermal hysteresis loop for laser intensities higher than 0.02 mW/μm2, in strong accordance with previous time-resolved pump-probe experiments on similar materials

Modification of aerosol properties due to relative humidity

International audienc

Spectroscopic and structural studies of bis[isopropoxy(thiocarbonyl)]sulfide, [(CH(3))(2)CHOC(S)](2)S

Structural and conformational properties of the molecule bis[isopropoxy(thiocarbonyl)]sulfide, [(CH(3))(2)CHOC(S)](2)S, have been studied by vibrational spectroscopy (IR and Raman) and quantum chemical calculations (HF and B3LYP with 6-31+G* basis sets). The crystal and molecular structure of the title compound was determined by X-ray diffraction methods. It crystallizes in the monoclinic C2/c space group with a = 8.4007(4), b = 13.5936(5), c = 10.3648(5) angstrom, beta = 106.024(4)degrees and Z = 4 molecules per unit cell. The molecules are sited on a crystallographic twofold axis passing through the sulphide atom and arranged in layers perpendicular to the b-axis. The solid state IR and Raman spectra of the compound give no sign of any other rotamer. (C) 2009 Elsevier B.V. All rights reserved.Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina (CONICET)Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET)[PIP 4695]Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (CIC), ArgentinaComisión de Investigaciones Científicas Provincia de Buenos Aires (CIC) - ArgentinaAgencia Nacional Cientifica y Tecnologica[PICT 33878]Agencia Nacional Cientifica y TecnologicaFacultad de Ciencias ExactasFacultad de Ciencias ExactasUniversidad Nacional de La PlataUniversidad Nacional de La PlataFAPESP of BrazilFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Deutscher Akademischer Austauschdienst (DAAD)Deutscher Akademischer Austausch Dienst (DAAD)CONICETConsejo Nacional de Investigaciones Científicas y Técnicas de Argentina (CONICET

Ageing of single pollen grains under controlled environment

International audienc

Observations of single pollen grains after ageing under controlled environment

International audienc

Spin crossover complexes [Fe(NH2trz)3](X)2*nH2O investigated by means of polarized Raman scattering and DFT calculations.

Vibrational spectra of the spin crossover (SCO) polymers [Fe(NH2trz)3](X)2*nH2O where NH2trz = 4-NH2-1,2,4-triazole and X = Cl, Br, BF4, and NO3 have been analyzed. Our results show that the anions and water molecules have no significant influence on the vibrational properties of the Fe(NH2-trz)3 polymer chains. A detailed study of the nitrate derivative, based on the DFT analysis of the polarized spectra of single crystals, has been undertaken to propose the normal mode assignment of the Raman peaks in the low spin state of the compound. Changes in the Raman spectra in the high spin state could therefore be analyzed and interpreted by several Raman bands identified as molecular probes of the SCO phenomenon. Various factors (laser power, humidity, pressure) that influence the transition temperatures and the hysteresis loops have been identified and adjusted for obtaining reliable measurements. We demonstrate in particular that all the techniques used to probe the phase transition process give comparable results providing that the sample environment is well controlled

Photochemistry of single particles using acoustic levitation coupled with Raman microspectrometry

The photoreactivity of single particles with atmospheric interest was studied by using an acoustic levitation system coupled to Raman microspectrometry. Both, inorganic and organic single particle phototransformation has been investigated without any surface contact. The Raman microspectrometry has suitably provided the identification, the chemical heterogeneity as well as the formation rates of products. Complex surface limited processes are demonstrated for photolysis of both nitrate-rich and sulfur-rich droplets.Fil: Tobon, Yeny A.. Centre National de la Recherche Scientifique; FranciaFil: Seng, Samantha. Centre National de la Recherche Scientifique; FranciaFil: Picone, Andrea Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Bava, Yanina Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Juncal, Luciana Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; Argentina. Centre National de la Recherche Scientifique; FranciaFil: Moreau, Myriam. Centre National de la Recherche Scientifique; FranciaFil: Romano, Rosana Mariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Barbillat, Jacques. Centre National de la Recherche Scientifique; FranciaFil: Sobanska, Sophie. Centre National de la Recherche Scientifique; Franci