Bi-exponential decay of Eu(III) complexed by Suwannee River humic substances: Spectroscopic evidence of two different excited species

摘要: Abstract The bi-exponential luminescence decay of europium (III) complexed by Suwannee River fulvic acid (SRFA) and humic (SRHA), is studied in time-resolved spectroscopy using two different gratings at varying delay after the laser pulse, increasing accumulation time order to obtain comparable signals. hypotheses found literature interpret this are (i) a back transfer from metal triplet state organic ligand (ii) radiative excited species. It shown that evolutions 5D0 → 7F0 5D0 → 7F2 luminescent transitions occurring between 10 300 μs delay. First, transition decreasing relative 5D0 → 7F1 showing slightly greater symmetry ‘slow’ component, also red shifted. Second, slight modification evidencing field splitting. No significant magnetic dipole, which less susceptible changes, noted line with expectations. adjusted either one or components. use simple component fit seems be well adapted for representing an average comportment these heterogeneous compounds, two-component constrained parameters times yields proposition spectra fast slow