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1) Lifetime plus triplet yield: k_ISC = Phi_T / tau_S, where tau_S is the observed singlet lifetime and Phi_T is the triplet quantum yield.
2) Rate decomposition: k_total = 1 / tau_S and k_ISC = k_total - k_r - k_IC - k_NR. This balances the observed decay against known competing channels.
3) Spin-orbit estimate: k_ISC = A x |H_SO|^2 x FCWD x exp(-DeltaE / k_B T) x g. Here, A is a model prefactor, H_SO is spin-orbit coupling, FCWD is the Franck-Condon weighted density factor, and g is degeneracy.
These relationships are widely used for screening and interpretation. Exact rates still depend on solvent, vibronic coupling, orbital character, and excited-state topology.
| Sample | Lifetime (ns) | Triplet Yield | H_SO (cm^-1) | Energy Gap (cm^-1) | Estimated k_ISC (s^-1) |
|---|---|---|---|---|---|
| Dye A | 8.4 | 0.62 | 18.5 | 950 | 7.3810e7 |
| Dye B | 5.1 | 0.41 | 11.2 | 1320 | 8.0392e7 |
| Sensitizer C | 12.0 | 0.79 | 24.0 | 640 | 6.5833e7 |
It measures how quickly an excited molecule changes spin multiplicity, usually from a singlet excited state to a triplet excited state.
Use lifetime plus triplet yield when you have direct photophysical measurements. It is usually the most practical starting point.
Heavy atoms can strengthen spin-orbit coupling and raise crossing probability. The factor lets you apply an empirical correction during comparison studies.
No. It is a semi-empirical screening model. Real systems also depend on solvent, geometry, vibronic overlap, and state ordering.
That usually means one or more input rates are inconsistent with the measured lifetime. Recheck units, assumptions, and experimental uncertainty.
Crossing time is the inverse of the rate constant. It provides an intuitive time-domain view of how fast intersystem crossing occurs.
Yes. Enter measured or estimated inputs for each compound and compare the resulting rates, branching fractions, and crossing times.
Prefer experimental lifetimes and yields when available. Use theoretical coupling and energy-gap values mainly for interpretation or early-stage screening.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.