Figure 6

Combined hierarchical 4 cluster analysis of all 12 samples together. On the left false colour representation of all samples with an individual resolution of 64 × 64 pixels showing a tissue area of 30 × 30 µm for each sample. Grey colours correspond to the surrounding tissue and the orange and red colours to the feature body and core. The spectra are given with the corresponding colours for the fingerprint region (700–1800 cm⁻¹) and the high frequency region (2800–3500 cm⁻¹), representing the mean results from 49152 spectra (64 × 64 pixels from 12 samples). Tissue ID numbers from left to right and top to bottom are: 29F3, 29F2, 29F1, 23F1, 36F1, 36H3, 36H1, 23F2, 29F4, 43F1, 36H2, 23H1. The indicated band positions are assigned to phenylalanine (1002 cm⁻¹), CH2/CH3-deformation mode¹³ (1310 cm⁻¹), -CH2-bending mode²⁸ (1440 cm⁻¹), protein β-sheet¹⁷ (1666 cm⁻¹), -CH2-symmetric stretching mode²⁹ (2850 cm⁻¹), the -CH2-antisymmetric stretching mode²⁹ (2881 cm⁻¹), Fermi resonance -CH2- + antisymmetric CH bending mode²⁹ (2918 cm⁻¹), lipid and protein -CH3 symmetric stretching mode²⁸ (2935 cm⁻¹).