First in-flight synchrotron X-ray absorption and photoemission study of carbon soot nanoparticles

F C Ouf (1) , P. Parent (2) , C. Laffon (2) , I. Marhaba (2) , Daniel Ferry (2) , B. Marcillaud (1) , E. Antonsson (3, 4) , S. Benkoula (3) , X.J. Liu (5) , C. Nicolas (3) , E. Robert (3) , M. Patanen (6, 3) , F.A. Barreda (7) , Olivier Sublemontier (7) , A. Coppalle (8) , Jerôme Yon (8) , F Miserque (9) , T Mostefaoui (10) , T.Z. Regier (11) , James Brian Alexander Mitchell (12) , C. Miron (13, 3)

1 IRSN - Institut de Radioprotection et de Sûreté Nucléaire
2 CINaM - Centre Interdisciplinaire de Nanoscience de Marseille
3 SSOLEIL - Synchrotron SOLEIL
4 Freie Universität Berlin
5 BUAA - Beihang University
6 University of Oulu
7 LEDNA - Laboratoire Edifices Nanométriques
8 CORIA - Complexe de recherche interprofessionnel en aérothermochimie
9 LECA - Laboratoire d'Etude de la Corrosion Aqueuse
10 Université Abderrahmane Mira [Béjaïa]
11 Canadian Light Source
12 IPR - Institut de Physique de Rennes
13 Horia Hulubei National Institute for Physics and Nuclear Engineering

Many studies have been conducted on the environmental impacts of combustion generated aerosols. Due to their complex composition and morphology, their chemical reactivity is not well understood and new developments of analysis methods are needed. We report the first demonstration of in-flight X-ray based characterizations of freshly emitted soot particles, which is of paramount importance for understanding the role of one of the main anthropogenic particulate contributors to global climate change. Soot particles, produced by a burner for several air-to-fuel ratios, were injected through an aerodynamic lens, focusing them to a region where they interacted with synchrotron radiation. X-ray photoelectron spectroscopy and carbon K-edge near-edge X-ray absorption spectroscopy were performed and compared to those obtained for supported samples. A good agreement is found between these samples, although slight oxidation is observed for supported samples. Our experiments demonstrate that NEXAFS characterization of supported samples provides relevant information on soot composition, with limited effects of contamination or ageing under ambient storage conditions. The highly surface sensitive XPS experiments of airborne soot indicate that the oxidation is different at the surface as compared to the bulk probed by NEXAFS. We also report changes in soot's work function obtained at different combustion conditions.

Domains: Chemical Sciences; Material chemistry

F C Ouf, P. Parent, C. Laffon, I. Marhaba, Daniel Ferry, et al.. First in-flight synchrotron X-ray absorption and photoemission study of carbon soot nanoparticles. Scientific Reports, 2016, 6 (1), pp.36495. ⟨10.1038/srep36495⟩. ⟨cea-01409226⟩