Unité Matériaux et Transformations (UMET) MR-CNRS 8207 , Université de Lille , 59655 Villeneuve d'Ascq , France.
Muséum National d'Histoire Naturelle, Sorbonne Université, CNRS UMR 7590, IRD , Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie , 75005 Paris , France.
Anal Chem. 2018 Jul 17;90(14):8379-8386. doi: 10.1021/acs.analchem.8b00689. Epub 2018 Jun 25.
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.
在软 X 射线范围内的 X 射线吸收光谱在许多研究领域中用于识别有机化合物和碳材料中官能团的性质。然而，这些官能团的浓度迄今为止仍然难以定量。我们使用参考材料（具有已知分子组成的聚合物和化合物）的 X 射线吸收近边结构（XANES）光谱，建立了测量的光密度与官能团浓度之间的相关性。该方法依赖于对总碳量进行归一化和对光谱进行解卷积的替代方法。它可以精确地定量测定 N/C 原子比（σ1 = 0.02 原子％）以及[芳族+烯属]基团（σ1 = 3.7 原子％），[酮+酚+腈]基团（σ1 = 2.2 原子％），[脂肪族]基团（σ1 = 11.2 原子％）和[羧酸]基团（σ1 = 7.4 原子％）的浓度。我们通过与在热解木质素样品上获得的核磁共振数据进行比较来验证这种定量。我们还提供了一个易于使用的 python 程序，用于自动化基于 XANES 的碳官能团浓度定量。
