Optical properties of europium compounds of the formulae:: Eu(NCS)3•2[N4(CH2)6]•8H2O and Eu(NO3)3•2[N4(CH2)6]•10H2O

Optical spectra of two types of europium compounds of the formulae: Eu(NCS)(3). 2[N-4(CH2)(6)]. 8H(2)O (1) and Eu(NO3)(2). 2[N-4(CH2)(6)]. 10H(2)O (2) at room and low temperatures are reported. The probabilities of f-f transitions were analysed and their temperature dependencies were explained. Unusually high oscillator strength values were found, particularly for europium thiocyanate. Comparison of the spectroscopic properties of the powder disc sample with the single crystal spectra was made. Absorption and excitation spectra of the title compounds in the region of f-f and C-T transitions in the 4.2-293 K range were studied and the vibronic components were assigned on the basis of IR and Raman data. Temperature dependence of the relative intensities of luminescence lines was examined and luminescence quenching was considered. The decay rimes for deuterated and non-deuterated samples were measured and the non-radiative processes were analysed. (C) 2000 Elsevier Science S.A. All rights reserved.