Structure and optical investigation of neodymium propylenediphosphonate NdH[O3P(CH2)3PO3]

The rare earth propylenediphosphonate, REH[O3P(CH2)(3)PO3], (RE[diph]), RE=La-Lu, Y included, have been synthesized by hydothermal technique. The crystal structure is monoclinic with C2/m as space group. The RE cation is coordinated by eight oxygen atoms from the phosphonate groups. The absorption spectra of neodymium compound, Nd[diph], are recorded in the spectral domain from UV to far IR, 30 000 to 3900 cm(-1), at various temperatures. In low temperature absorption spectra an unique local environment is found for the neodymium ion in agreement with the crystallographic data. The parametric simulation is performed on 67 experimental levels from 182 Kramer's doublets of 4f(3) configuration of neodymium, using an approximate C-2v symmetry for the rare earth ion site in Nd[diph], with 14 free ion and 9 real crystal field parameters. A good r.m.s. standard deviation of 16.8 cm(-1) is obtained. (C) 2001 Elsevier Science B.V. All rights reserved.