J. Legendziewicz et M. Borzechowska, Heteronuclear Eu : Cu trichloroacetate and its polynuclear Eu analogue; their spectroscopy and magnetism, J ALLOY COM, 300, 2000, pp. 353-359
Single crystals of europium trichloroacetates of formulae Eu(CCl3COO)(3). 2
H(2)O (1) and CuEu2(CCl3COO)(8). 6H(2)O (2) were obtained. They are isomorp
hic with the respective Er and (Nd:Cu) compounds. Absorption, excitation, e
mission as well as magnetic susceptibility measurements in the 1.7-300 K ra
nge were carried out. The spectroscopic and magnetic data were analysed. Th
e absorption spectra of compounds 1 and 2 at room and low temperature were
compared and the differences in the splitting of the levels described as a
result of the CF effect and the effect of the d-electron ion. The emission
of EU3+ was completely quenched in the heteronuclear single crystal (2) at
293 and 77 K. The oscillator strengths of the f-f transitions were calculat
ed and the radiative processes analysed. Weak vibronic components recorded
in the low-temperature excitation and emission spectra were promoted by loc
alised M-L and internal ligand modes. The number of Stark components of the
L'S'J' levels in both systems (1 and 2) was analysed and the symmetries of
the metal centres determined and compared with the results of X-ray analys
is. The value of the splitting of the first excited state, 7F(1), was used
to explain the LT and HT magnetic properties of the systems under investiga
tion. The role of the heteroatom was considered and related to the data of
earlier reported respective systems. (C) 2000 Elsevier Science S.A. All rig
hts reserved.