Thermodynamics and laser luminescence spectroscopy of binary and ternary complexation of Am3+, Cm3+ and Eu3+ with citric acid, and citric acid + EDTA at high ionic strength

Am3+, Cm3+ and Eu3+ with citric acid formed MCit and MCit23- and with EDTA + citric acid, M(EDTA)(Cit)4− complexes at 6.60 m (NaClO4). Positive enthalpy and entropy values are reported for the Am3+-cit3− complexes. Luminescence excitation spectra and lifetime measurement studies validated the formation of Eu(Cit)(H2O)6, Eu(Cit)2(H2O)33-, Eu(Cit)2(H2O)23-, Eu(Cit)2(H2O)3− and Eu(EDTA)(Cit)4−.