Optical study of praseodymium dicarboxylate [Pr(H2O)]2[O2C(CH2)3CO2]3•4H2O

Praseodymium dicarboxylate, [Pr(H2O)](2)[O2C(CH2)(3)CO2].4H(2)O]-glutarate, Pr[glut], is synthesized by hydrothermal techniques. The title compound crystallizes in the monoclinic space group C2/c (No. 15). The rare earth cation is coordinated by nine oxygen atoms, eight oxygen atoms from the carboxylate groups and one from the water molecule. The local symmetry of Pr site is low, C-s. The absorption spectra of Pr[glut] are recorded from the visible to the far IR domain at 300. 77 and 9 K. Under various Ar- laser excitations no emission is detected from P-3(0) and D-1(2) excited levels of Pr3+ ion. In the low temperature absorption spectra only one electronic line is recorded for H-3(4)-->P-3(0) transition. It confirms a unique local environment for the rare earth ion in Pr[glut]. The utility of the 'barycenter curves' in the attribution of electronic lines is demonstrated. Energy level scheme of 36 Stark components is deduced from the absorption spectra. The parametric calculation was performed on the whole (4)f(2) (Pr3+) configuration with the starting set of crystal field parameters obtained previously for the Eu3+ ion in the isostructural compound. Eight free ion and nine phenomenological crystal field parameters in C-2nu symmetry reproduce quite well several electronic levels of Pr3+ ion experimentally observed in Pr[glut]. A good r.m.s. standard deviation of 14.8 cm(-1) is obtained. (C) 2002 Elsevier Science B.V. All rights reserved.