The authors describe the use of an ultraviolet light-emitting diode (UV LED), Nichia NSHU590E, as a 373 nm excitation light source for fluorescence lifetime measurements. A frequency-domain technique has been chosen to demonstrate that the UV LED can be efficiently intensity modulated by driving the radio-frequency signal over a range of modulation frequencies from 10 kHz up to 330 MHz. Time-resolved measurements have been performed by using a fluorophore with a very long lifetime of 10.2 mu s and fluorophore with a very short lifetime of 0.15 ns. Application of LEDs for lifetime-based chemical sensing is discussed.
Henryk Szmacinski and Qing Chang, "Micro- and Sub-nanosecond Lifetime Measurements Using a UV Light-Emitting Diode," Appl. Spectrosc. 54, 106-109 (2000)