Mixed complexes of alkaline earth uranyl carbonates: a laser-induced time-resolved fluorescence spectroscopic study

The interaction of the alkaline earth ions Mg(2+), Sr(2+) and Ba(2+) with the uranyl tricarbonato complex has been studied by time-resolved laser-induced fluorescence spectroscopy. In contrast to the non-luminescent uranyl tricarbonato complex at ambient temperature the formed products show luminescence properties. These have been used to determine the stoichiometry and complex stabilities of the formed compounds. As the alkaline earth elements are located in an outer shell of the complex the influence of the type of the alkaline earth element on the stability constant is not very drastic. The stability constants range from log beta113 degrees = 26.07+/-0.13 to log beta113 degrees = 26.93+/-0.25 for the first reaction step and from log beta213 degrees = 29.73+/-0.47 to log beta213 degrees = 30.79+/-0.29 for the overall complex formation with two alkaline earth ions.