Figure 8.

C K-edge XANES spectra obtained on the particles and cells shown in Figure 7. Dashed lines correspond to absorption energies for different organic functional groups: 285 eV ($1s\to {\pi }_{\mathrm{C}=\mathrm{C}}^{\ast }$transitions in aromatics or unsaturated carbon), 285.2 eV ($1s\to {\pi }_{\mathrm{C}=\mathrm{C}}^{\ast }$transitions in aromatics), 286.6 eV (1 s→π^* transitions in ketones, pyridines, and phenols), 287.5 eV (3 s→σ^* transitions in aliphatics), 288.2 eV (1 s→π^* transitions in amides), 288.5 eV ($1s\to {\pi }_{\mathrm{C}=\mathrm{O}}^{\ast }$ transitions in carboxylic acids), 288.7 eV ($1s\to {\pi }_{\mathrm{C}=\mathrm{O}}^{\ast }$ transitions in carboxyls in acidic polysaccharides), and 289.4 eV (1 s→3p/σ^* transitions in alcohols, ethers, and hydroxylated aliphatic compounds).