This simulation shows a Jablonski diagram with the singlet ground state (S0), first and second excited singlet states (S1, S2), and first excited triplet state (T1). Vibrational substates are shown for each electronic state.
Adjust the rate constant sliders to change the rates of fluorescence, phosphorescence, intersystem crossing, internal conversion, and reaction. Arrow thicknesses update to reflect each pathway's quantum yield, which is the fraction of absorbed photons that exit through that process. Mouse over the transitions arrows to identify the type of transition.
The light intensity and absorbance rate sliders are included as a learning tool. Notice that changing them has no effect on the quantum yields shown on the diagram.
A ⚠ symbol and amber color appear on a slider's value label when that rate constant is outside the typical literature range for that process. The simulation remains fully functional at these values; the warning is a reminder that the combination may not represent a physically realistic molecule.
Quantum yield describes the fraction of absorbed photons that produce a specific photophysical outcome. After a molecule absorbs light, the excited state can relax through several competing pathways such as fluorescence, phosphorescence, internal conversion, or intersystem crossing. The quantum yield of each pathway represents the probability that an absorbed photon ultimately leaves through that process.
Scroll to zoom and drag the screen to pan.
The quantum yield (\(\Phi\)) of a photophysical process is defined as the number of events of that process divided by the number of photons absorbed. Photochemists use quantum yields to quantify how efficiently absorbed energy produces a particular outcome such as fluorescence emission or a photochemical reaction.
Because excited states can decay through multiple competing pathways, the quantum yield depends on the relative magnitudes of the rate constants connecting the states in the Jablonski diagram. In this simulation, the quantum yields are calculated from the branching ratios of the rate constants for each pathway.
Rate constant ranges were chosen based on representative orders of magnitude from the reference below. Each slider covers an expanded range that extends beyond typical laboratory values to allow exploration of extreme cases. When a slider is within the typical literature range for that process, the value label is shown normally. When it falls outside that range, the label turns amber and shows a ⚠ symbol. The simulation remains fully functional in either case.
Source: Edinburgh Instruments. “What is a Jablonski (Perrin-Jablonski) Diagram?”
This simulation was created in the Department of Chemical and Biological Engineering at University of Colorado Boulder for LearnChemE.com by Alexander Osterbaan under the direction of Professor Christopher N. Bowman. Address any questions or comments to LearnChemE@gmail.com.