Editing Time-resolved spectroscopy (section)

==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, [[Ultrafast laser spectroscopy#Time-correlated single photon counting|TCSPC]] (picoseconds and slower)
* With a [[streak camera]] (picoseconds and slower)
* With  [[Intensified charge-coupled device|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 effect|"Kerr gate"]], which allows the scattered [[Raman spectroscopy|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.