Excited State Lifetime Calculator

Analyze fluorescence decay with clear inputs and instant outputs. Explore rate balances and quantum efficiency. Build reliable photophysics estimates for labs, classes, and reports.

Calculator Inputs


Example Data Table

Sample kr (s-1) knr (s-1) kISC (s-1) kIC (s-1) Lifetime (ns)
Coumarin dye 1.20×108 8.50×107 1.10×107 4.00×106 4.5455
Organic emitter 9.40×107 5.10×107 8.00×106 6.00×106 6.2893
Metal complex 3.20×107 1.80×107 1.50×107 7.00×106 13.8889

Formula Used

The core lifetime expression is τ = 1 / (kr + knr + kISC + kIC).

Here, τ is the excited state lifetime in seconds. Each k term is a first-order decay rate constant.

Fluorescence quantum yield is ΦF = kr / ktotal.

When observed lifetime and fluorescence yield are known, the radiative rate becomes kr = ΦF / τ.

The combined nonradiative loss rate is kloss = 1/τ − kr.

How to Use This Calculator

  1. Select the calculation mode that matches your available photophysical data.
  2. Enter rate constants, or supply lifetime with fluorescence quantum yield.
  3. Press Calculate Lifetime to display the result above the form.
  4. Review lifetime, decay rate, and yield fractions for interpretation.
  5. Use the CSV or PDF buttons to export the result summary.