『Abstract
　Multiple Internal Reflection Fourier Transform Infra-Red (MIR-FTIR) spectroscopy was developed and used for in situ flow-through experiments designed to study the process of organic acid promoted silicate dissolution. In tandem with the FTIR analysis, ex situ X-ray scattering was used to perform detailed analyses of the changes in the surface structure and chemistry resulting from the dissolution process. Phthalic acid and forsteritic glass that had been Chemically Vapour Deposited (CVD) onto an internal reflection element were used as reactants, and the MIR-FTIR results showed that phthalic acid may promote dissolution by directly binding to exposed acid attachment apparently follows a t^1/2 dependence, indicating that attachment is a diffusive process. The diffusion coefficient of phthalic acid was estimated to be approximately 7×10^-6 cm² s^-1 in the solution near the interface with the glass. Shifts in the infrared absorption structure of the phthalate complexed with the surface compared to the solute species indicate that phthalate forms a seven-membered ring chelate complex. This bidentate complex efficiently deplete Mg from the glass surface, such that after reaction as much as 95% of the Mg may be removed. Surface depletion in Mg causes adsorbate density to fall after an initial attachment stage for the organic ligand. In addition, the infrared analysis shows that silica in the near surface polymerizes after Mg removal, presumably to maintain charge balance. X-ray reflectivity shows that the dissolution rate of forsteritic glass at pH 4 based on Mg removal in such flow-through experiments was equal to 4×10^-12 cm² s^-1 (geometric surface area normalized). Reflectivity also shows how the surface mass density decreases during reaction from 2.64 g cm^-3 to 2.2 g cm^-3, consistent with preferential loss of Mg from the surface. Auxiliary batch experiments with forsteritic glass films deposited onto soda glass were also completed to add further constraints to the mechanism of reaction. By combining reflectivity with diffuse scatter measurements it is shown that the primary interface changes little in terms of atomic-scale roughness even after removal of several hundred angstroms of material. These measurements unequivocally show how a dicarboxylic acid bonds to and may chelate the dissolution of a magnesium-bearing silicate. At the molecular level the solid surface retreat may best be described by a depinning model where Mg is preferentially removed and residual silica tetrahedra polymerize and act to episodically “pin” the surface.』

1. Introduction
2. Methods and materials
　2.1. Chemicals, solutions, flow cell, and reaction protocol
　　2.1.1. Sample A
　　2.1.2. Sample B
　　2.1.3. Sample C
　　2.1.4. Flow cell
　　2.1.5. Phthalic acid
　2.2. CVD preparation of glassy forsteritic thin films
　2.3. Infrared measurements
　2.4. X-ray scattering
　2.5. AFM
　2.6. XPS
　2.7. ICP-OES
3. Results and discussion
　3.1. Characterisation of the thin films before reaction
　3.2. FTIR of solutes and adsorbates
　　3.2.1. Solution spectra
　　3.2.2. Adsorbate spectra
　3.3. X-ray reflectivity post reaction
4. Summary and conclusions
Acknowledgments
References