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L'équipe "Métallurgie et Surfaces" de l'Institut Jean Lamour , invite Valerie J. Alstadt (Pennsylvania State University) pour un séminaire intitulé :
"Characterizing Mineral Surfaces with Respect to Ice Nucleation"
Date et lieu :
Mardi 12 mai 2015 à 14h00
Institut Jean Lamour
Faculté des Sciences et Technologies, Vandœuvre-lès-Nancy
Salle de séminaire entrée 3A, 3ème étage
Understanding how ice nucleation occurs on the molecular scale for mineral dust particles has important implications for cloud formation and climate. Changes in the kaolinite surface structure due to sulfuric acid exposure have been investigated using Diffuse Reflectance Infrared Fourier Transformed Spectroscopy (DRIFTS). Ice nucleation onset experiments were also performed to determine the changes in ice nucleation activity. The interaction of kaolinite with acetic acid was modeled using Density Functional Theory. Results indicate that acid treatment causes changes to functional groups on the surface of kaolinite, but that the product of the acid-mineral reaction is responsible for the corresponding decrease in the ice nucleation. Further studies on the nanoscale will take place to investigate the adsorption of water on mineral surfaces using an Atomic Force Microscope (AFM), Temperature Programmed Desorption Spectroscopy (TPDS) and Reflection Absorbance Infrared Spectroscopy (RAIRS). Together, these results provide a surface perspective of ice nucleation phenomena that gives insight into the surface sites that may promote ice nucleation.