Langmuir and Langmuir-Blodgett films of three new rare earth heteropoly compounds with long-chain alkyl gruops DODA/Ln(PW~1~1)~2 (Ln=La, Sm, Eu) were prepared and characterized by π-A isotherm, FT IR spectra, UV-vis absorption spectra, low-angle X-ray diffraction (LAXD), fluorescence spectra and surface photovoltage spectroscopy (SPS). The results show that they have good films-forming property on air/water interface. The molecular areas for these monolayers at zero pressure are estimated to be 0.45～0.50 nm^2. LB films have the good interlayer order, rare earth heteropoly anions are sandwiched between dilongchain alkyl groups as an inorganic layer. DODA/Ln(PW)~1~1)~2LB films have characteristic fluorescene-cemission spectrum of Sm and Eu, surface photovoltage spectroscopy has stronger photoelectric response.

Key words: HETEROPOLYACID, RARE EARTH, L-B MEMBRANE, QUATERNARY AMMONIUM COMPOUNDS, INFRARED SPECTROPHOTOMETRY, ULTRAVIOLET SPECTROPHOTOMETRY, X-RAY SMALL ANGLE SCATTERING ANALYSIS