Figure 2. Absorbance spectra for the non-irradiated (green line), irradiated (red line) and fluoride-irradiated (blue line) enamel, without pH-cycling (A) and after pH-cycling (B). Amide I (1653 cm⁻¹), Carbonate v3 (1460 and 1425 cm⁻¹), Phosphate v1 and v3 (960 and 1040cm⁻¹).