SYNTHESIS AND SPECTROSCOPIC PROPERTIES OF PRASEODYMIUM(III) ACETATE HYDRATE

A new synthesis for the quasi-one-dimensional compound Pr(CH3COO)3.H2O and its deuterated analogue Pr(CD3COO)3.D2O is reported. Well-resolved absorption, luminescence, and Raman measurements on single crystals of these compounds as well as the diluted system Ce(CH3COO)3.H2O:1% Pr3+ down to 5 K are reported and analyzed. Due to high-energy O-H stretching vibrations of the directly coordinated water molecule, excited states are efficiently depopulated by nonradiative multiphonon relaxation. In the concentrated crystal, the relaxation rate of the 3P0 excited state at 5 K is approximately 2 x 10(8)s-1 and > 10(9)s-1 for the deuterated and nondeuterated compound, respectively. In addition, cross relaxation contributes to the nonradiative depopulation of the 1D2 excited state. It is thus likely that energy migration along the chain is not important. The 3H4 --> 3P0 absorption has a relatively intense sideband, 65% and 20% of the total intensity for Pr(CH3COO)3.H2O and Ce(CH3COO)3.H2O:1% Pr3+, respectively. Double excitations involving nearest neighbors in the chain contribute two-thirds of the sideband intensity of the undiluted compound, one-third being vibronic.