Near-infrared spark source excitation for fluorescence lifetime measurements

We have extended the range of excitation wavelengths from spark sources used in single photon timing fluorometry into the near infrared by means of the all-metal coaxial flashlamp filled with an argon-hydrogen gas mixture. At 750 nm this mixture gives ∼15 times the intensity available from pure hydrogen for a comparable pulse duration. Measurements are demonstrated by using the laser dye IR-140 in acetone, for which a fluorescence lifetime of 1.20 ns is recorded.