We have prepared and characterized several lanthanide ion complexes of multidentate ligands or chelates in an effort to develop new upconverting luminescent labels that can be immune to autofluorescence and photobleaching. This study has involved the characterization of various chelates of Nd, Er, and Tm with respect to relative luminescent efficiency and excited-state lifetimes and explored various two-photon stepwise excitation mechanisms. Using peak laser powers near 100 kW, the upconversion emissions of Nd in Nd(EDTA)_2 ^5- at 386 nm, Er in Er(DPA)_3 ^3- at 550 nm, and Tm in Tm(DPA)_3 ^3- at 480 nm, at levels of ∼10^-12 moles can be detected.
© 2005 Optical Society of America
(170.4580) Medical optics and biotechnology : Optical diagnostics for medicine
(170.6280) Medical optics and biotechnology : Spectroscopy, fluorescence and luminescence
(190.7220) Nonlinear optics : Upconversion
(300.1030) Spectroscopy : Absorption
Xudong Xiao, Jeanne P. Haushalter, and Gregory W. Faris, "Upconversion from aqueous phase lanthanide chelates," Opt. Lett. 30, 1674-1676 (2005)