Fig. 3.

⁵D₀ ← ⁷F₀ excitation (left) and ⁵D₀ → ⁷F₂ emission (right) spectra for aqueous solutions of 0.040 mol/l [Eu(CDA)₃]⁶⁻, and after addition of 1.2 and 1.6 mol/l of l-Arg at 295 K and at a pH of 12.2 (from bottom to top). The luminescence was monitored at approximately 615 nm for the excitation spectra, while the emission spectra were recorded following excitation at the maximum of the ⁵D₀ ← ⁷F₀ excitation spectra.