Abstract: STUDY ON ff ABSORPTION SPECTRA OF Nd3＋ Cyanex272 COMPLEX AND Nd3＋Cyanex301 COMPLEXChen Yingzhong Xu Jingming Chen Jing Zhu Yongjun(Institute of Nuclear Energy Technology,Tsinghua University,,Beijing 102201)ABSTRACTThe computer programm developed in INET for calculating ff transition spectra of lanthanides complex is improved and used for the calculation of Nd3＋Cyanex272 (bis(2,4,4trmethylpentyl) phophinic acid)complex and Nd3＋Cyanex301 (bis(2,4,4trimethylpentyl) dithiophosphinic acid) complex on the possible complex structure models.By comparison of the calculated results with the experimental date,assignment to the ff hypersensitive spectra of the neodymium complex is given.The most possible structure of Nd3＋Cyanex272 complex is octahedra with 6 ligands and Nd3＋Cyanex301 complex structure is cubic with 8 ligands.Key words Bis(2,4,4trmethylpentyl) phophinic acid(Cyanex272) Bis(2,4,4trimethylpentyl) dithiophosphinic acid(Cyanex301) Complex structure Trivalent fions Calculation of absorption spectra