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Neodymium complexes (Nd(DBM)3·H2O and Nd(DBM)3·Phen) were studied by photoacoustic spectroscopy from near-IR to mid-IR region. Low excited energy levels, relaxation processes of the complexes and the nephelauxetic effect were discussed according to the comparison with electron absorption spectra of free neodymium ion. The interaction between Nd(III) and the ligands in solid complexes was investigated on the basis of band shifts and intensity change. [Copyright &y& Elsevier]

The amplitude and the phase of the photoacoustic (PA) signal generated in Nd(DBM)3 and Nd(DBM)3·Phen (DBM: dibenzoylmethane; Phen: 1,10-phenanthroline) complex powders were examined. By using PA amplitude and phase spectra, together with IR and fluorescence spectra, the intramolecular relaxation processes and the fluorescence properties of DBM were studied. And a new method to calculate the relaxation time of the ligand of rare earth complexes was presented. Compared with the free ligand DBM, the relaxation time of DBM in Nd(DBM)3 and Nd(DBM)3·Phen complexes calculated by the new method had the order: free ligand>in Nd(DBM)3>in Nd(DBM)3·Phen. The fluorescence spectra verified the validity of the new method. The intramolecular energy transfer models were established on the basis of the calculated results and the fluorescence spectra. [Copyright &y& Elsevier]

The photoacoustic (PA) amplitude spectra of Eu(Dbm)3Phen, Eu0.8Gd0.2(Dbm)3Phen and Eu0.8Nd0.2(Dbm)3Phen complexes (Dbm: dibenzoylmethane; Phen: phenanthroline) have been measured, and the PA phase data of the different complexes calculated. The PA amplitude spectra combined with the luminescence spectra reflected the variation of the luminescence efficiency, and the PA phase is directly relative to the lifetime of Eu3+5D0 level. The luminescence efficiency and the lifetime of Eu3+5D0 level increase when Gd3+ is introduced, while they decrease greatly when Nd3+ is added, which is due to the different intermolecular energy transfer processes. The models of energy transfer and relaxation processes of Eu0.8Gd0.2(Dbm)3Phen and Eu0.8Nd0.2(Dbm)3Phen are established. [Copyright &y& Elsevier]