## 3 Results
### Hexacyanorrate Anions
The random-oriented intercalated LDH exhibited two overlapping bands of similar intensity, with the higher wavenumber band being the broader of the two. This higher wavenumber band at 2041 cm\({}^{-1}\) was still visible in the oriented sample, with unaltered band shape and width, but the sharper, lower wavenumber band at 2035 cm\({}^{-1}\) was no longer visible. Therefore, both these intense bands were interpreted to correlate with \(T_{1u}\) in \(O_{h}\), and their separation is proof of a local reduction of symmetry. They attributed this effect to a change to \(D_{3d}\) symmetry by the ferrocyanide anion, resulting in a splitting of this mode into \(E_{u}\) and \(A_{2u}\) components. The symmetry reduction is a result of the orientation of the ferrocyanide anions in the interlayer space of the LDH, which lies with two opposed triangular faces of the coordination octahedron parallel to the internal surfaces of the LDH hydroxide layers. Under these circumstances, the \(E_{u}\) component is likely to be broader than the \(A_{2u}\) component. Furthermore, the \(E_{u}\) component is x,y-polarized in the molecular axis system, while the \(A_{2u}\) component is z-polarized. This explains the detected selectivity. The molecular three-fold z-axis, the crystallographic c-axis, and the direction of light propagation are all parallel in the oriented LDH sample. Two Raman spectroscopic studies on hexacyanoferrate intercalated LDH were published by [PERSON] et al. [102] and [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] [30]. Details about the symmetry of the hexacyanoferrate anion and its reduction and oxidation behavior after intercalation in LDH can be obtained by comparing the Raman spectra with the infrared spectra. Free Fe(CN)\({}_{6}\)\({}^{4-}\) will exhibit three vibrational modes with \(A_{1g}\) at 2098 cm\({}^{-1}\) and \(E_{g}\) at 2062 cm\({}^{-1}\) in the Raman spectrum, and \(T_{1u}\) at 2044 cm\({}^{-1}\) in the infrared spectrum. For the intercalated LDH, they detected bands in the Raman spectrum at 2136, 2094 and 2065 cm\({}^{-1}\) for hexacyanoferrate(II) intercalated LDH and at 2164, 2136, 2094 and 2059 cm\({}^{-1}\) for hexacyanferrate(III) intercalated LDH, clearly supporting the fact that a change in the site symmetry had taken place as well as partial reduction. Lowering the site symmetry to \(C_{3}\) after intercalation in LDH would predict four bands in the Raman spectra for both the hexacyanoferrate (II) and hexacyanoferrate(III) anions, resulting in theoretically eight modes. In reality, it is expected that a number of these modes will overlap, causing the detection of fewer bands. It is clear that the case of hexacyanoferrate(III) intercalation in LDH generally results in a partial reduction of Fe\({}^{3+}\) to Fe\({}^{2+}\). In contrast to the other anionic groups studied here, the reduction of hexacyanoferrate(III) results in clear changes in the infrared and Raman spectra. These changes are also clearly visible in the XPS Fe 2p spectra. Integration of the peak areas for both the Fe 2p3/2 of Fe(II) and Fe(III) allows for a direct measure of the amount of reduction. In this sample, 45% of the Fe(III) was reduced to Fe(II).