Figure 3. VSFS spectra of DLPS monolayers at the air/water interface at pH 7.4: Black, red and blue traces correspond to monolayers in the absence of Ca²⁺, in the presence of 10 mM Ca²⁺ and 200 mM Ca²⁺, respectively.

VSFS spectrum of phosphate stretch (A), carboxylate stretch (B) and ester stretch (C). Solid lines are fits to the experimental spectra.