FTIR spectroscopic semi-quantification of iron phases: A new method to evaluate the protection ability index (PAI) of archaeological artefacts corrosion systems

Abstract

This study proposes an innovative approach to semi-quantify the main iron corrosion phases found in corrosion systems of archaeological artefacts. This method is based on the treatment of Fourier Transform Infrared Spectroscopy (FTIR) data using a homemade spectra decomposition software (PALME). Its application was first tested on mixtures of pure iron corrosion standards. After optimization, it was used to study real archaeological samples and evaluate the stability of their corrosion system. Considering that reliable and repetitive results were reached using extremely small quantities of material, this method can be particularly suitable for the study of iron-based objects of cultural interest.

Micro- and Nanoscale Spectroscopic Investigations of Threonine Influence on the Corrosion Process of the Modified Fe Surface by Cu Nanoparticles

“…The reference FT-IR and RS spectra obtained for the CuNPs-Fe surface after its immersion in 0.5 M HCl solution for 24 h are shown in Figure 2 a,b, respectively. The FT-IR and RS spectra are dominated by bands which can be assigned to a corrosion product, which is a mixture of different compounds such as goethite (α-FeOOH), lepidocrocite (γ-FeOOH), feroxyhyte (δ-FeOOH), akaganeite (β-FeOOH), hematite (α-Fe 2 O 3 ), and cuprite (Cu 2 O) [ 49 , 50 , 51 , 53 , 54 , 55 , 56 ]. In the FT-IR spectra ( Figure 2 a), the appearance of bands around at 920 cm −1 , 810 cm −1 , and 630 cm −1 can be assigned to α-FeOOH [ 49 ].…”

“…In the FT-IR spectra ( Figure 2 a), the appearance of bands around at 920 cm −1 , 810 cm −1 , and 630 cm −1 can be assigned to α-FeOOH [ 49 ]. However, the presence of a significantly broadened band around 810 cm −1 and 630 cm −1 also suggests the formation of β-FeOOH on the corroded CuNPs-Fe surface [ 50 ]. In addition, the band with maximum at 1127 cm −1 , with a shoulder at 1160 cm −1 , and the broad band with a maximum at around 950 cm −1 , mean the presence of lepidocrocite (γ-FeOOH) and feroxyhyte (δ-FeOOH) on the corroded CuNPs-Fe surface cannot be excluded [ 49 , 50 , 51 , 53 ].…”

“…However, the presence of a significantly broadened band around 810 cm −1 and 630 cm −1 also suggests the formation of β-FeOOH on the corroded CuNPs-Fe surface [ 50 ]. In addition, the band with maximum at 1127 cm −1 , with a shoulder at 1160 cm −1 , and the broad band with a maximum at around 950 cm −1 , mean the presence of lepidocrocite (γ-FeOOH) and feroxyhyte (δ-FeOOH) on the corroded CuNPs-Fe surface cannot be excluded [ 49 , 50 , 51 , 53 ]. Another overlapped band at 660 cm −1 in Figure 2 a may suggest the formation of Cu 2 O on the corroded CuNPs-Fe surface [ 54 , 55 ].…”

“…SERS, SEIRA, and nano-SEIRA are promising techniques applied in various fields including biomedicine, catalysis research, and biotechnology [ 43 , 44 , 45 , 46 , 47 , 48 ]. They can be also very useful in corrosion studies, especially in studies of the mechanism of the corrosion inhibition process, at the micro- and nanoscale [ 49 , 50 , 51 ].…”

A tool for assisting phase identification by micro‐Raman spectroscopy

“…This proposed solution is, in some ways, similar to PALME, a software for Fourier transform infrared spectra decomposition …”