XPS Analysis of Combustion Aerosols for Chemical Composition, Surface Chemistry, and Carbon Chemical State

Abstract

Carbonaceous aerosols can vary in elemental content, surface chemistry, and carbon nano-structure. Each of these properties is related to the details of soot formation. Fuel source, combustion process (affecting formation and growth conditions), and postcombustion exhaust where oxidation occurs all contribute to the physical structure and surface chemistry of soot. Traditionally such physical and chemical parameters have been measured separately by various techniques. Presented here is the unified measurement of these characteristics using X-ray photoelectron spectroscopy (XPS). In the present study, XPS is applied to combustion soot collected from a diesel engine (running biodiesel and pump-grade fuels); jet engine; and institutional, plant, and residential oil-fired boilers. Elemental composition is mapped by a survey scan over a broad energy range. Surface chemistry and carbon nanostructure are quantified by deconvolution of high-resolution scans over the C1s region. This combination of parameters forms a distinct matrix of identifiers for the soots from these sources.

Surface Chemical Composition of Size-Fractionated Urban Walkway Aerosols Determined by X-Ray Photoelectron Spectroscopy

“…As they grew to the accumulation mode, more organics from the gas phase might have condensed on the surfaces and some might have oxidized further to form oxygen-containing surface groups (Muller et al 2007;Vander Wal et al 2011). Thus, these particles had organic surface layers with multiple functional groups.…”

“…High sulfur and nitrogen concentrations on the surfaces of the accumulation-mode particles also suggest that the reactive uptake of NO x and SO 2 was quite feasible. Chemical reactions could further proceed among these adsorbed species (Prince et al 2002;Vander Wal et al 2011). …”

“…A number of studies have used XPS to analyze particulate matters collected with filters (Hutton and Williams 2000;Zhu et al 2001;Paoletti et al 2003;Song and Peng 2009;Vander Wal et al 2011). XPS analysis provides important information about elemental concentrations and chemical states (Faude and Goschnick 1997;Lei et al 2003;Lau et al 2009;Ng et al 2011).…”

Chemical and Isotopic Composition of Humic-Like Substances (HULIS) in Ambient Aerosols in Guangzhou, South China

“…Among these sulfur species, the sulfur groups of thiophenes, thioesters, and mercaptanes may be formed from the S-containing compounds directly emitted from wetlands such as rice paddy fields, the litter layer of forest soils, the aerobic decomposition of food wastes, oil-fired boiler, and so on (Yi et al 2008Wu et al 2010;Vander Wal et al 2011). The occurrence of sulfone sulfur suggested the possibility of SO x incorporation into OM via photochemical processes.…”

Chemistry characterization of jet aircraft engine particulate matter by XPS: Results from APEX III

“…Peak assignments were made per the NIST compilation (NIST X-ray Photoelectron Spectroscopy Database; http://srdata.nist.gov/xps/), allowing for shifts due to sample charging. Precision of reported percentages of the different C1s components is judged to be ~ 6% as + 2ߪ, this measure being based upon examination of residuals expressing goodness of fit upon variation of peak position or width [30].…”