Actualités
Séminaire de Roger ATKINSON le 9/12 à 14H
Roger Atkinson, Professeur à l'Université de Californie à Riverside, donnera un séminaire au LISA le vendredi 9 décembre à 14h intitulé :
Titre : "Alkane and Cycloalkane Atmospheric Chemistry"
Résumé : Alkanes and cycloalkanes are important components of gasoline and of vehicle exhaust, and of non-methane volatile organic compounds in urban air. Alkoxy radicals are key intermediates formed during alkane and cycloalkane degradations. Alkoxy radicals react in the atmosphere by decomposition, isomerization, and reaction with O2. The products formed after alkoxy radical isomerization have proven difficult to identify and quantify. Our research concerning the identification and quantification of hydroxycarbonyl products formed from the OH radical-initiated reactions of alkanes will be presented, together with a very recent extension of this research to C7-C10 cycloalkanes.
Roger Atkinson est un chimiste de l'atmosphère qui travaille sur l'étude des cinétiques et des mécanismes d'oxydation des COV par les oxydants atmosphériques (OH, NO3, O3). Il est l'auteur de plus de 500 publications sur ce sujet parmi lesquelles de nombreux monographes qui font références dans le domaine. C'est un scientifique d'une grande renommée internationale et c'est pour nous un honneur de l'accueillir au LISA.
Wednesday, 23 November 2011
Séminaire de Stuart J. PIKETH le 21/11 à 11H
Stuart J. PIKETH
Professeur et Directeur du Climatology Research Group de l'Université de Johannesburg, en Afrique du Sud "Airborne measurement of aerosols and cloud properties over southern Africa, the Middle East, Australia and India" Lundi 21 Novembre à 11h dans la salle de réunion du LISA
(Faculté des Sciences, Batiment P4, 4eme étage, pièce 456)
Thursday, 10 November 2011
Conférence de John H. Seinfeld le 23/11 à 10h30
Aerosols and Climate
Prof. John H. Seinfeld
Division of Chemistry and Chemical Engineering
California Institute of Technology
Pasadena, CA
Lavoisier Lecture #1
Department of Chemistry
University Paris Diderot – Paris 7
November 23, 2011
10:30 am
Atmospheric particles generally exert a cooling effect on climate that counteracts warming from greenhouse gases. The amount of radiative forcing due to aerosols is generally considered as the most uncertain component of the overall radiative forcing from pre-industrial to present day.
Aerosols scatter and absorb incoming solar radiation (referred to the direct effect) and act as cloud condensation nuclei (referred to as the indirect effect). While most aerosol inorganic and organic constituents are purely scattering in nature, black carbon absorbs solar radiation and heats the atmosphere. The overall optical properties of the aerosol depend on the fraction of black carbon. The effect of aerosol perturbations on cloud properties is considered as the most uncertain of the aerosol effects. In this presentation, we will review the current understanding of aerosol effects on climate and the prospects for improving estimates of aerosol forcing of climate.
Amphithéâtre Buffon, Rez-de-chaussée bas
15 rue Hélène Brion, 75013 Paris
Wednesday, 09 November 2011
Conférence de John H. Seinfeld le 24/11 à 11h
Atmospheric Organic Aerosols
Prof. John H. Seinfeld
Division of Chemistry and Chemical Engineering
California Institute of Technology
Pasadena, CA
Lavoisier Lecture #2
Department of Chemistry
University Paris Diderot – Paris 7
November 24, 2011
11:00 am
Organic compounds are a significant fraction of atmospheric particulate matter. Secondary organic aerosol (SOA), formed from condensation of low-volatility species from the oxidation of gas-phase organic compounds, often dominates the total organic aerosol. Understanding the formation of SOA has proven to be a challenge, owing to the difficulty in identifying and quantifying the gas-phase oxidation chemistry, as well as the complex, multi-generation oxidative chemistry that leads to the aerosol formation. Laboratory chamber data provide the basic understanding of SOA formation. In chamber experiments, specific compounds of interest can be isolated and studied under well-controlled oxidation environments, allowing one to achieve a more detailed and direct characterization of the composition, chemical, and physical properties of the aerosol. Field measurements provide important datasets for understanding the chemistry and life cycles of ambient aerosols. The combination of chamber and ambient data yields important insights into our understanding of aerosol chemistry. Results from chamber experiments and integrated analysis of multidimensional and multiple worldwide aerosol mass spectrometry datasets will be presented, and their implications for the evolution of atmospheric aerosols will be discussed.
Amphithéâtre Buffon, Rez-de-chaussée bas
15 rue Hélène Brion, 75013 Paris
Wednesday, 09 November 2011
Séminaire de Michel ATTOUI le 18/11 à 11H
Michel ATTOUI (Maître de conférence en physique à l'UPEC) donnera un séminaire au LISA en salle de réunion (456 P4) le 18 novembre à 11h00
Titre: "Métrologie (détection, génération et comptage) des aérosols de diamètres inférieurs à 10 nanomètres"
Wednesday, 02 November 2011