The fluorescence stability of a series of atypical amphiphilic rare earth complex LB films is studied under the following two conditions: (1) measure the LB films every 40 seconds; (2) measure the LB films once a week. The fluorescence intensity decreases slowly in a linear relationship for the first case, nearly 96% of the original intensity is kept after 30 times of irradiation. The fluorescence intensity decreases in a monoexponential relationship for the second case. The time τ that the fluorescence intensity decayed to 1/e of its original value is about 10 weeks, e.g., the τ value of n[Eu(TTA) ~3Phen] : n(AA)=1 : 1 LB film is 11.4 weeks. When the LB films are excited for the same times (> 1), fluorescence of the LB films for the first case is more intense than that for the second case. The fluorescence stability was studied by the UV-vis spectra and low angle X-ray diffraction. The decreased absorbance of the rare earth complexes in LB films contributed to the decreased fluorescence intensity with time passing by. However, all the LB films can emit detectable fluorescence even after half one year, indicating that the rare earth complexes in LB films have better fluorescence intensity. The reason can be attributed to the high ordered orientation of the rare earth complexes in LB films.

Key words: RARE EARTH METAL COMPLEX, L-B MEMBRANE, FLUOROSPECTROPHOTOMETRY, STABILITY