Judd-Ofelt Analysis on Trifluoroacetate Europium Complexes for Liquid Laser Media

Four europium trifiuoroacetate complexes, Eu（CF3COO）3＂bpy（bpy=2,2＇-bipyridine）（l）, Eu（CF3COO）3＂ phen（phen=l,10-phenanthroline）（2）, Eu（CF3COO）3.2bp（bp=benzophenone）（3） and Eu（CF3COO）3-2tppo（tppo=triphenyl- phosphine oxide）（4） were synthesized and characterized by elemental analysis, Fourier transform infrared（FTIR） spectroscopy, photoluminescence（PL） spectroscopy and thermogravimetric analysis（TGA）. The PL spectra of the complexes at room temperature show the strong typical Eu3＋ ion red emission, due to the efficient energy ＂antenna absorption＂ of ligands and transitions of Eu3＋ ion between 5Do---7Fj（j-0-4）. The long lifetime and high quantum yield reflect that the multiphonon relaxations by coupling to O--H and C--H vibrations were reduced. According to the photoluminescent spectra, the Judd-Ofelt parameters f22 and 04 of the complexes were calculated and the radiative properties were also presented. The 5D0 radiative lifetime, quantum yield and the stimulated emission cross-section of the complexes are excellent, which prove that they have promising optical properties for liquid laser. The thermal analyses indicate that they are quite stable to heat.