IN-SITU DEHYDROXYLATION IN EU3-DOPED SOL-GEL SILICA()

Fluorescence line narrowing and lifetime measurements are used to char acterize the extents of clustering and hydroxyl quenching, respectivel y, in Eu3+-doped sol-gel silica glasses prepared using europium triflu oromethanesulfonate (triflate). A triflate ((CF3SO3)(3)Eu) rather than a traditional nitrate (Eu(NO3)(3) . 6H(2)O) precursor is used as the rare earth ion dopant in order to determine the feasibility of effecti ng chemical dehydroxylation via in situ fluorination by incorporating fluorine directly as a ligand substituent of the Eu3+ precursor. In sa mples doped only with Eu3+, the use of the triflate precursor leads to no noticeable differences in hydroxyl quenching of Eu3+ fluorescence or Eu3+ aggregation relative to samples prepared with a nitrate precur sor. Beneficial effects are observed, however, in samples codoped with Al3+ or Sr2+. When Al3+ or Sr2+ is included in the synthesis, a reduc tion in hydroxyl quenching of Eu3+ is observed when the triflate precu rsor is used relative to the nitrate precursor. In addition, (CF3SO3)( 3)Al is found to be as effective at inhibiting Eu3+ clustering as the previously reported Al(NO3)(3) . 9H(2)O and (C4H9O)(2)Al-O-Si(OC2H5)3 precursors. The effect of incoporating fluorine via FSi(OC2H5)(3) is a lso briefly considered and gives mixed results which differ for nitrat e and triflate Eu3+ precursors.