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Author Ma, X.; Pavlidis, G.; Dillon, E.; Beltran, V.; Schwartz, J.J.; Thoury, M.; Borondics, F.; Sandt, C.; Kjoller, K.; Berrie, B.H.; Centrone, A. pdf  url
doi  openurl
  Title Micro to nano : multiscale IR analyses reveal zinc soap heterogeneity in a 19th-century painting by Corot Type A1 Journal article
  Year (down) 2022 Publication Analytical chemistry Abbreviated Journal  
  Volume 94 Issue 7 Pages 3103-3110  
  Keywords A1 Journal article; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)  
  Abstract 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 (mu-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 approximate to 500 and approximate to 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 (mu-FTIR approximate to 10(2) mu m(3), O-PTIR approximate to 10(-1) mu m(3), PTIR approximate to 10(-5) mu m(3)). 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 mu m(3)) zinc soap domains. We identify Zn stearate and Zn oleate crystalline soaps with characteristic narrow IR peaks (approximate to 1530-1558 cm(-1)) and a heterogeneous, disordered, water-permeable, tetrahedral zinc soap phase, with a characteristic broad peak centered at approximate to 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.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000766206700011 Publication Date 2022-02-09  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0003-2700; 5206-882x ISBN Additional Links UA library record; WoS full record; WoS full record; WoS citing articles  
  Impact Factor Times cited Open Access OpenAccess  
  Notes Approved no  
  Call Number UA @ admin @ c:irua:187380 Serial 8897  
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Author Ma, X.; Beltran, V.; Ramer, G.; Pavlidis, G.; Parkinson, D.Y.; Thoury, M.; Meldrum, T.; Centrone, A.; Berrie, B.H. doi  openurl
  Title Revealing the distribution of metal carboxylates in oil paint from the micro- to nanoscale Type A1 Journal article
  Year (down) 2019 Publication Angewandte Chemie: international edition in English Abbreviated Journal  
  Volume 58 Issue 34 Pages 11652-11656  
  Keywords A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)  
  Abstract Oil paints comprise pigments, drying oils, and additives that together confer desirable properties, but can react to form metal carboxylates (soaps) that may damage artworks over time. To obtain information on soap formation and aggregation, we introduce a new tapping-mode measurement paradigm for the photothermal induced resonance (PTIR) technique that enables nanoscale IR spectroscopy and imaging on highly heterogenous and rough paint thin sections. PTIR is used in combination with mu-computed tomography and IR microscopy to determine the distribution of metal carboxylates in a 23-year old oil paint of known formulation. Results show that heterogeneous agglomerates of Al-stearate and a Zn-carboxylate complex with Zn-stearate nano-aggregates in proximity are distributed randomly in the paint. The gradients of zinc carboxylates are unrelated to the Al-stearate distribution. These measurements open a new chemically sensitive nanoscale observation window on the distribution of metal soaps that can bring insights for understanding soap formation in oil paint.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000478409100001 Publication Date 2019-06-21  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1433-7851; 0570-0833 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor Times cited Open Access  
  Notes Approved no  
  Call Number UA @ admin @ c:irua:163573 Serial 8478  
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