XANES-Based Quantification of Carbon Functional Group Concentrations

X-ray absorption spectroscopy in the soft X-ray range is used in many research fields to identify the nature of functional groups in organic compounds and carbon materials. However, the concentrations of these functional groups have so far remained difficult to quantify. Using X-ray absorption near...

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Bibliographic Details
Published in:Analytical chemistry (Washington) 2018-07, Vol.90 (14), p.8379-8386
Main Authors: Le Guillou, Corentin, Bernard, Sylvain, De la Pena, Francisco, Le Brech, Yann
Format: Article
Language:English
Subjects:
Absorption spectroscopy
Aliphatic compounds
Astrophysics
Carbon
Chemical Sciences
Chemistry
Condensed Matter
Correlation analysis
Earth Sciences
Functional groups
Geophysics
Lignin
Material chemistry
Materials Science
NMR
Nuclear magnetic resonance
Organic chemicals
Organic compounds
Phenols
Physics
Polymers
Reference materials
Sciences of the Universe
Soft x rays
X-ray absorption spectroscopy
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Summary:X-ray absorption spectroscopy in the soft X-ray range is used in many research fields to identify the nature of functional groups in organic compounds and carbon materials. However, the concentrations of these functional groups have so far remained difficult to quantify. Using X-ray absorption near edge structure (XANES) spectra of reference materials (polymers and compounds of known molecular composition), we established a correlation between measured optical densities and functional groups concentration. This methodology relies on an alternative method for normalization to the total amount of carbon and for deconvolution of the spectra. It allows precisely quantifying the N/C atomic ratio (σ1 = 0.02 atom %) as well as the concentration of [aromatic + olefinic] groups (σ1 = 3.7 atom %), [ketone + phenol + nitrile] groups (σ1 = 2.2 atom %), [aliphatic] groups (σ1 = 11.2 atom %) and [carboxylic] groups (σ1 = 7.4 atom %). We validated this quantification by comparing with nuclear magnetic resonance data obtained on pyrolized lignin samples. We also provide an easy-to-use python program automating XANES-based quantification of carbon functional group concentrations.
ISSN:0003-2700
1520-6882
DOI:10.1021/acs.analchem.8b00689