Jablonski Diagram
Definition
An energy-level diagram showing the ground state, singlet excited states, and triplet state of a molecule, with arrows indicating absorption, internal conversion, fluorescence, intersystem crossing, and phosphorescence pathways.
- Key transitions shown
- Absorption, fluorescence, phosphorescence, internal conversion, and intersystem crossing
- Primary states mapped
- Ground state (S0), singlet excited states (S1, S2), and triplet states (T1, T2)
Common questions
What does a Jablonski diagram show?+
A Jablonski diagram is an energy-level cartoon that maps how a molecule absorbs light and releases it through different pathways. It shows ground state, excited singlet states, triplet states, and the transitions between them, including fluorescence, phosphorescence, and internal conversion.
What are the different energy states in a Jablonski diagram?+
The diagram typically shows S0 (ground state), S1 and S2 (singlet excited states), and T1 and T2 (triplet states). Each level represents a different electronic energy state of the molecule, with arrows showing how the molecule transitions between them.
Why does intersystem crossing matter in a Jablonski diagram?+
Intersystem crossing is the transition from a singlet state to a triplet state, or vice versa. This pathway is crucial because it leads to phosphorescence, a longer-lived emission that makes some molecules glow after the light source is removed, which has forensic applications in detecting trace evidence.
Related terms
- Phosphorescence
- Light emission from the triplet excited state (T1) via a spin-forbidden radiative transition; characterised by emission persisting after the excitation source is...
- Stokes Shift
- The wavelength difference between the excitation peak and the emission peak of a fluorophore. A positive Stokes shift (emission at longer wavelength...
- Absorption
- The purification technique in which a crude antiserum is mixed with antigen preparations from cross-reacting species. Cross-reactive antibodies bind those antigens and...
- Beer-Lambert Law
- A = εbc. Absorbance equals molar absorptivity times path length times concentration. The linear relation between absorbance and concentration that makes UV-Vis...
- Chromophore
- The molecular subunit responsible for a dye's colour, typically a conjugated double-bond system; chemical erasure destroys the chromophore while leaving the decolourised...
- Fluorescence
- Light emission following absorption of light at a shorter (higher-energy) wavelength. Fluorescein absorbs blue-green excitation light and emits yellow-green light. The emitted...
- Fluorescence Lifetime
- The average time a fluorophore spends in the S1 excited state before emitting a fluorescence photon; typically 1-10 ns for organic fluorophores,...
- Fluorescence Quantum Yield (Phi)
- The fraction of absorbed photons that result in fluorescence emission (0 to 1); determines the brightness of a fluorescent signal and is...
- Kubelka-Munk Model
- A diffuse-reflectance theory relating the measured reflectance of a scattering-plus-absorbing layer to its absorption and scattering coefficients; used in forensic paint and...
- Molar Extinction Coefficient (ε)
- The intrinsic absorptivity of a molecule at a given wavelength, in L/(mol·cm); oxyhaemoglobin at 415 nm has ε ≈ 125,000, making it...
- Phosphoroscope
- A rotating chopper that alternately blocks the excitation beam and the detector. Fluorescence dies during the blocked window, phosphorescence persists, so only...
- Quantum Yield (Φ)
- Photons emitted divided by photons absorbed. A unit-less efficiency between 0 and 1. Quinine sulphate in 0.5 N sulphuric acid sits at...
Explained in these topics
- Fluorescence and Phosphorescence SpectroscopyThe vertical energy-level cartoon showing S0, S1, S2, T1, T2 and the radiative and non-radiative transitions (absorption, fluorescence, phosphorescence, intern...
- Light-Matter Interaction: Absorption, Reflection, FluorescenceAn energy-level diagram showing the ground state, singlet excited states, and triplet state of a molecule, with arrows indicating absorption, internal conversi...