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Fluorescence lifetime (exp)

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Fluorescence lifetime (exp) diagram
This calc assumes exponential decay of fluorescence to determine the half-life and lifetime (which is defined as 1/[decay constant], and corresponds to decay to a level of 1/e (~36.8%). It is not suitable for biexponential or other decay functions. "t=0" should be taken at a point where the excitation source is completely off.
Intensity at t=0
Intensity at t=x
Time x

Fluorescence half-life
Fluorescence lifetime
Rate constant
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Note that this calc can be used for other exponential decays such as radioactive decay or a first-order chemical reaction.
Typical fluorescence lifetimes are of the order of ps for small organics, ns for large organics and inorganics, and µs for triplet states (although much longer lifetimes can be found).