Time-resolved Fluorescence Spectroscopy
Time-resolved fluorescence spectroscopy is an extension of fluorescence spectroscopy. Here, the fluorescence of a sample is monitored as a function of time after excitation by a flash of light. The time resolution can be obtained in a number of ways, depending on the required sensitivity and time resolution:
- With fast-detection electronics (nanoseconds and slower)
- With Time Correlated Single Photon Counting, TCSPC (picoseconds and slower)
- With a streak camera (picoseconds and slower)
- With intensified CCD (ICCD) cameras (down to 200 picoseconds and slower)
- With optical gating (femtoseconds-nanoseconds) - a short laser pulse acts as a gate for the detection of fluorescence light; only fluorescence light that arrives at the detector at the same time as the gate pulse is detected. This technique has the best time resolution, but the efficiency is rather low. An extension of this optical gating technique is to use a "Kerr gate", which allows the scattered Raman signal to be collected before the (slower) fluorescence signal overwhelms it. This technique can greatly improve the signal:noise ratio of Raman spectra.
This technique uses convolution integral to calculate a lifetime from a fluorescence decay.
Read more about this topic: Time-resolved Spectroscopy