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SUMMARY:EESS talk on "The chemical composition of the interface of (some) 
 atmospheric particles: A molecular view"
DTSTART:20211207T121500
DTEND:20211207T131500
DTSTAMP:20260429T182450Z
UID:7c542860d9c9a040108ac17409c8aec2aa18f09b722f7acacb32d783
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr Michel Rossi\, Emeritus Senior Scientist\, Group Ludwig\, E
 PFL\nAbstract:\nA flowing gas experiment is used to “interrogate” the 
 gas-solid interface of specific atmospheric particles using reactive probe
  gases that interact to various extents with surface functional groups mak
 ing up the interface.\nFor instance\, a basic probe gas such as trimethyla
 mine may interact with surface acidic functional groups such as carboxylic
  acids or acidic OH groups in a neutralization reaction. We will first exp
 lain the advantages and disadvantages of the used method based on molecula
 r beam sampling mass spectrometry and subsequently present three examples 
 that describe applications of the method to atmospheric chemistry: (a) the
  interface of amorphous carbon generated from incomplete combustion/oxidat
 ion processes or biomass burning has a wealth of surface functional groups
  revealing both its provenance as well as past atmospheric processing. Mor
 e often than not the interface has both acidic and basic as well as oxidiz
 ing and reducing properties side-by-side\;\n(b) The atmospheric fate of se
 mivolatile organic compounds that are partially oxidized is subject to the
  presence of secondary organic aerosols and atmospheric mineral dust parti
 cles. We will undertake a brief tour of the heterogeneous interaction of t
 hree partially oxidized semivolatile compounds with two proxies of mineral
  dust particles (Kaolinite\, Arizona Test Dust) in terms of adsorption and
  desorption kinetics. We will highlight the relationship between organic s
 tructure and abundance of surface functional groups of the mineral dust pr
 oxy\; (c) the interfacial composition of an atmospheric particle greatly c
 ontrols the role it plays in oxidative stress on living organisms in terms
  of supporting Reactive Oxygen Species (ROS) through interfacial reactions
  in the presence of atmospheric oxygen. Laboratory experiments using antio
 xidants in solution correlate with the abundance of redox-cycling surface 
 functional groups. It turns out that the interface acts as a redox catalys
 t in order to accelerate surface oxidation in the presence of excess atmos
 pheric oxygen.\n\nShort biography:\nPhD in physical chemistry (University 
 of Basel\, 1975). postdoctoral fellow at Stanford Research Institute (SRI 
 International\, 1976-78)\; Swiss National Science Foundation fellowship (1
 979)\; rose through the ranks of Stanford Research Institute to end up as 
 program manager/senior scientist in the Chemical Kinetics Department/Physi
 cal Sciences Division (1991)\; adjoint scientifique and chargé de cours a
 t EPFL/DGR\, Laboratoire de Pollution Atmosphérique et Sol (LPAS)\, in ch
 arge of the heterogeneous atmospheric chemistry program (1991-2008)\; seni
 or scientist at PSI in the Laboratory of Atmospheric Chemistry (LAC/ENE) (
 2009- 2019)\; guest scientist at EPFL since 2017 maintaining a level of sc
 ientific activity in the GR-Lud/IIE Department to date.
LOCATION:https://epfl.zoom.us/j/63900222242?pwd=OXluejhzTklCbkdWakkvaUFCSG
 Vndz09
STATUS:CONFIRMED
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