Judd-Ofelt analysis of lanthanide doped silica-PEG hybrid sol-gels

Lanthanide complexes of 1,10-phenanthroline (phen), 2,2'-bipyridine (bipyridyl, bpy) and dipicolinate (dpa), together with uncomplexed lanthanide ions (Ln = Nd, Sm, Dy, Ho, Er) were doped into silica-polyethylene glycol (SiO2 PEG) inorganic organic hybrid materials. The samples were prepared via a sol-gel process. The intensities of the f-f transitions in the absorption spectrum were analysed by application of the Judd-Ofelt theory. Sets of phenomenological Omega(lambda) intensity parameters have been extracted. The hypersensitive transitions are strongly influenced by the drying time of the sol-gel glass. The PEG molecules compete with the organic ligand for complex formation to the lanthanide ions complex. 1,10-Phenanthroline and bipyridyl complexes are not stable in the presence of PEG, but the dipicolinate complexes are.