Fluorescence lifetime measurement in the time domain requires excitation from a well separated single bunch using synchrotron light sources.In the colliding mode of the Beijing Electron Positron ColliderⅡ (BEPCⅡ),a hybrid filling pattern was realized such that a single bunch was placed in the middle of a large gap between two multi-bunch groups.Detection of fluorescence lifetime,based on the excitation of the light pulse from this designated single-bunch,was established at Beamline 4B8 of the Beijing Synchrotron Radiation Facility (BSRF).The timing signal of the BEPCⅡ was utilized as a trigger to gate this fluorescence event.L-Tryptophan amino acid,a known lifetime standard,was selected to assess the lifetime measurement performance.The measured lifetime was consistent in both colliding and single-bunch mode with the time resolution down to 450 ps.Moreover,both the bunch purity and the fine structure of the hybrid filling pattern were characterized.
