Time-resolved fluorescence spectroscopy using pulsed lasers

Abstract

The mode-locked laser systems available as excitation sources for fluorescence decay measurements using the method of time-correlated single photon counting are discussed. Because of the high stability requirements for successful operation of these lasers, an alternative pulsed excitation source, employing a CW laser with a cavity dumper is proposed. Although the pulse width from this source is large compared to those from the mode-locked systems, it is shown that when combined with a reliable deconvolution procedure, lifetimes in the nanosecond and sub-nanosecond time domain may be measured with fair accuracy. Examples are presented showing how the fluorescence from two component mixtures may be resolved, both spectrally and temporally, and how exciplex formation may be analysed.