The hypersensitive spectra of [Er(H2O)8]3+and [Er(HL2)3] (HL=(2-ethylhexyl)phosphinic acid) based on possible model structures were calculated By comparison of the former with corresponding experimental data the assignments to most of the experimental bands were given. The origin of experimental peaks were analyzed through the crystal field splitting of energy levels and the transition strength between different energy levels. The bands didn't split apparently in the spectrum of [Er(H2O)83+ because of relative small crystal field splitting, low degeneracy and narrow range of transition savelength. In the case of [Er(HL2)3], the spectra band splits into several sep. sep. peaks because of relative strong crystal field effects, high symmetry of the inner coordination sphere, high energy degeneracy, and distributed range of transition wavelength.

Key words: PHOSPHONIC ACID P, MOLECULAR STRUCTURE, SPECTROGRAPHIC ANALYSIS, HYDRATE, TRANSITION, ERBIUM COMPLEX, COORDINATE CHEMISTRY