The analysis of sinusoidal modulated method used for measuring fluorescence lifetime

This paper has built a system with a sinusoidal modulated LED as the excitation source. Such exciter was used upon the sample EU(2)L'(3) . nH(2)O(L'=C(4)H(4)O(4)). Both the excitation light and the (5)D(0)-(7)F(2) emission of Eu(3+) ion were measured. Fluorescence lifetime, which approximate to 0. 680 ms, can then be obtained from the measured excitation and fluorescence waveforms by non-linear least square curve fitting based on the principle of phase-shift measurement of fluorescence lifetime. Data processing methods considering respectively the high order harmonics in the modulation and multi-exponential decay of the fluorescence were discussed. A method of utilizing Fourier series expandedness to amendatory the result was put forward. Accordingly, the applicability for phase-shift method was expanded as well as a more exact result was acquired.