Université Toulouse III - Paul Sabatier - Bat. 3R4 - 118 route de Narbonne - 31062 Toulouse Cedex 09 - France

Accueil > Événements > Séminaires 2016

Chemical and structural characterization of soot particles by mass spectrometry and Raman spectroscopy

Cristian FOCSA, Université Lille 1, Laboratoire PhLAM

Soot particles are products of the incomplete combustion of biomass or
fossil fuels. The adsorbed phase of soot can strongly affect the
chemical and physical properties of the particle surface, playing an
important role in many fields including combustion, health and climate.

From the climate point of view, aerosol-cloud interaction represents
the largest source of uncertainty in global climate models. Soot
particles can be involved in cloud formation, one of the best examples
is aviation-induced cloudiness, in form of contrail cirrus generated by
injection of soot particles into the upper troposphere. The impact of
these soot particles on cirrus formation depends on their ice nucleating
potential. During the last years, different works have studied the ice
nucleation potential of soot particles, but there are important
discrepancies between the results reported. One of the main reasons
behind these discrepancies is the lack of a complete characterization of
the soot particles studied. Soot particles can have very different
physico-chemical properties depending on their production conditions,
e.g. different fuels or combustion techniques. Therefore a complete
physico-chemical characterization is needed to link the ice nucleation
potential measured with specific soot properties.
In this seminar we will introduce the different techniques
available at
our laboratory to study the structure and chemical surface composition
of soot particles. We use Raman and FTIR microscopy techniques to
characterize the structure of soot particles, and two-step Laser
Desorption/Ionization Mass Spectrometry (L2MS) and Secondary Ions Mass
Spectrometry (SIMS) to determine their surface chemical composition. We
will present the characterization of soot from various sources
(laboratory, aviation, road traffic) to illustrate the performance of
these techniques. Finally, preliminary results from a recently developed
experiment dedicated to ice nucleation on soot will be presented.