Complexity, Measurement Scheme, and the Spectral Properties of Fluorophores

It is well known that the lifetime of fluorophores is typically in the range of 1-10 nsec, and that it is easily possible to spend 50,000- 500,000 for lifetime instrumen- 

Prior to describing the possible applications of laser-diode fluorometry, it is important to understand the two methods now used to measure fluorescence lifetimes these being the time-domain (Tl)/4 5 24 and frequency-domain (FD) or phase-modulation methods.(25) In TD fluorometry, the sample is excited by a pulse of light followed by measurement of the time-dependent intensity. In FD fluorometry, the sample is excited with amplitude-modulated light. The lifetime can be found from the phase angle delay and demodulation of the emission relative to the modulated incident light. We do not wish to fuel the debate of TD versus FD methods, but it is clear that phase and modulation measurements can be performed with simple and low cost instrumentation, and can provide excellent accuracy with short data acquisition times. 

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Instrument Complexity, Measurement Scheme, and the Spectral Properties of Fluorophores... 

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