Fluorescence spectra of matrix-isolated praseodymium triodide molecules

Abstract

Listen

Translate article

Fluorescence spectra of PrI 3 molecules isolated in Ar and Xe matrices have been measured for the first time. More than 40 transitions have been measured using Hg excitation and have been assigned to transitions within the 4 f 2 configuration. An interpretation of the spectrum is given based on an energy level diagram calculated by adopting an intermediate coupling model and considering electronic repulsion, spin-orbit and “crystal field” interactions. The “crystal field” is assumed to arise from iodide ions located at the points of an equilateral triangle giving the PrI 3 molecule D 3 h symmetry. Results of least-squares refinement calculations for the PrI 3 molecule give the values A 2 0 = −282.5 cm −1 ; A 4 0 = 36.1 cm −1 ; A 6 0 = 26.8 cm −1 ; A 6 6 = 231.7 cm −1 . The effect on the parametric values in going from ninefold coordination (Pr 3+ in LaCl 3 crystals) to threefold coordination (PrI 3 molecules) is calculated using the point charge model, and compared with the experimental results. It is suggested that the matrix isolated rare-earth halide molecules are useful systems for studying matrix perturbation effects and for detailed m.o. calculations to fix the splitting parameters.