Term: single-photon timing
https://doi.org/10.1351/goldbook.S05689

Definition:
Technique that permits recovery of the parameters characterizing a fluorescence decay after pulse excitation (in particular excited-states lifetimes). It is based on the creation of a time histogram of many stochastic events involving the time delay between the electronic excitation of a molecule or material and its emission of a photon from an excited state. A key to the technique is that no more than one photon strike the detector per pulsed excitation. Excitation is commonly achieved with a flash from a repetitive nanosecond lamp or diode laser or a CW operated laser (mode-locked laser). The essential components of the hardware are a device to measure the excitation-emission delay time and another to determine the relative frequency of photons reaching the detector at each delay time. Delay times are usually measured with a time-to-amplitude-converter (TAC), using voltage to measure the delay between a start and a stop signal. The frequency of events with each delay is stored in a multi-channel analyser. This term is preferred to time-correlated single-photon counting.

Related Terms:
1) recovery (http://doi.org/10.1351/goldbook.R05206).
2) fluorescence (http://doi.org/10.1351/goldbook.F02453).
3) excited state (http://doi.org/10.1351/goldbook.E02257).
4) lamp (http://doi.org/10.1351/goldbook.L03447).
5) diode laser (http://doi.org/10.1351/goldbook.D01747).
6) laser (http://doi.org/10.1351/goldbook.L03459).
7) mode-locked laser (http://doi.org/10.1351/goldbook.M03959).
8) channel (http://doi.org/10.1351/goldbook.C00970).
9) single-photon counting (http://doi.org/10.1351/goldbook.P04629).

Source: PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 420 (https://doi.org/10.1351/pac200779030293)

Citation: 'single-photon timing' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.S05689

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