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影响因子：7.4

DOI码：10.1021/acs.analchem.1c04182

发表刊物：Analytical Chemistry

摘要：Formation and aggregation of metal carboxylates (metal soaps) can degrade the appearance and integrity of oil paints, challenging efforts to conserve painted works of art. Endeavors to understand the root cause of metal soap formation have been hampered by the limited spatial resolution of Fourier transform infrared microscopy (μ-FTIR). We overcome this limitation using optical photothermal infrared spectroscopy (O-PTIR) and photothermal-induced resonance (PTIR), two novel methods that provide IR spectra with ≈500 and ≈10 nm spatial resolutions, respectively. The distribution of chemical phases in thin sections from the top layer of a 19th-century painting is investigated at multiple scales (μ-FTIR ≈ 102 μm3, O-PTIR ≈ 10–1 μm3, PTIR ≈ 10–5 μm3). The paint samples analyzed here are found to be mixtures of pigments (cobalt green, lead white), cured oil, and a rich array of intermixed, small (often ≪ 0.1 μm3) zinc soap domains. We identify Zn stearate and Zn oleate crystalline soaps with characteristic narrow IR peaks (≈1530–1558 cm–1) and a heterogeneous, disordered, water-permeable, tetrahedral zinc soap phase, with a characteristic broad peak centered at ≈1596 cm–1. We show that the high signal-to-noise ratio and spatial resolution afforded by O-PTIR are ideal for identifying phase-separated (or locally concentrated) species with low average concentration, while PTIR provides an unprecedented nanoscale view of distributions and associations of species in paint. This newly accessible nanocompositional information will advance our knowledge of chemical processes in oil paint and will stimulate new art conservation practices.

合写作者：Georges Pavlidis,Eoghan Dillon,Victoria Beltran,Jeffrey Schwartz,Mathieu Thoury,Ferenc Borondics,Christophe Sandt,Kevin Kjoller

第一作者：Xiao Ma

论文类型：期刊论文

通讯作者：Barbara H.Berrie,Andrea Centrone

卷号：94,

期号：7

页面范围：3103–3110

是否译文：否

发表时间：2022-02-09

收录刊物：SCI

发布期刊链接：https://pubs.acs.org/doi/10.1021/acs.analchem.1c04182