Versatile, High Intensity, Nanosecond Light Source for Fluorescence Lifetime Measurements

A high power, low duty cycle source is described for fluorescence lifetime measurements. Light pulses with a time constant of 7 to 15 nsec are produced by a coaxial capacitor, air discharge. The radiant emittance observed is approximately 10 6 W cm −2 . The spectral distribution of the source radiation can be shifted from the ultraviolet to the visible region by adjusting the gap length. Equations are derived to predict the light output energy and the time constant of the discharge as a function of gap length. The fluorescence lifetime of a 10 −5 M solution of quinine sulfate was measured to demonstrate the usefulness of the source. Other possible applications are discussed.