Intensity analysis and energy-level modeling of Nd3+ in Nd3+:Y2O3 nanocrystals in polymeric hosts

Abstract

Optical absorption and emission intensities are investigated for Nd3+ in nanocrystalline Nd3+:Y2O3. Room temperature absorption intensities of Nd3+(4f3) transitions in synthesized Nd3+:Y2O3 nanocrystals have been analyzed using the Judd–Ofelt (J-O) approach to obtain the phenomenological intensity parameters. The J-O intensity parameters are used to calculate the spontaneous emission probabilities, radiative lifetimes, and branching ratios of the Nd3+ transitions from the upper multiplet manifolds to the corresponding lower-lying multiplet manifolds L2S+1J of Nd3+(4f3). The emission cross sections and room temperature fluorescence lifetimes of the important intermanifold F43/2→I4J (J=9/2,11/2,13/2,15/2) transitions have been determined. We also compare the spectra of the Nd3+:Y2O3 nanocrystals to those of the nanocrystals embedded in polymeric matrices of epoxy and chitosan, and we find similarities in terms of the detailed Stark energy levels of the Nd3+ ion in the Y2O3 nanocrystalline host. The 300 K spectra are analyzed for the energy (Stark) level transitions between the L2S+1J multiplet manifolds of Nd3+(4f3). The results of this study are also compared with a crystal-field splitting analysis reported earlier for single-crystal Nd3+:Y2O3 grown by a modified flame fusion method. We find that the spectroscopic properties of our nanocrystals embedded in polymeric hosts compare favorably with other ceramic and single-crystal forms of Nd3+:Y2O3 currently available.