Figure 2.

(A,B) Experimental SFG spectra in the amide I region for LE10 peptides at the air–water interface (gray), with Ca²⁺ ion interaction at different times after CaCl₂ injection (red), and following CaC₂O₄ mineralization (blue). The spectra were acquired under (A) achiral SPS and (B) chiral PSP polarization combinations. The fits (black) are superimposed onto the experimental data. (C,D) Calculated amide I SFG spectra for peptides before and after Ca²⁺ ion interaction agree well with experimental spectra.