Spectroscopic properties of Ho$^{3+}$ in Ho$^{3+}$:Y$_{2}$O$_{3}$ Nanocrystals*

Spectroscopic properties are investigated for Ho$^{3+}$ in nanocrystalline Ho$^{3+}$:Y$_{2}$O$_{3}$. Room temperature absorption intensities of Ho$^{3+}$(4$f^{10})$ transitions in synthesized Ho$^{3+}$:Y$_{2}$O$_{3 }$nanocrystals have been analyzed using the Judd-Ofelt (J-O) approach in order 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 Ho$^{3+}_{ }$transitions from the upper multiplet manifolds to the corresponding lower-lying multiplet manifolds $^{2S+1}L_{J}$ of Ho$^{3+}$(4$f^{10})$. An 8K absorption spectra was also taken. From that spectra an in-depth crystal field splitting analysis was performed on selected manifolds. A comparison of the manifold splittings for Ho$^{3+}$:Y$_{2}$O$_{3}$ (nano) was made to that observed for Ho$^{3+}$ in large single crystals of Y$_{2}$O$_{3}$. Presently we are investigating the fluorescence properties of this nanocrystal. A comparative study of Ho$^{3+}$(4$f^{10})$ ions suggests that synthesized Ho$^{3+}$:Y$_{2}$O$_{3 }$nanocrystals could be an excellent alternative to single-crystal Ho$^{3+}$:Y$_{2}$O$_{3 }$for certain applications especially in the visible region.