How does a Jablonski diagram work?
In molecular spectroscopy, a Jablonski diagram is a diagram that illustrates the electronic states of a molecule and the transitions between them. The states are arranged vertically by energy and grouped horizontally by spin multiplicity.
What is fluorescence explain with Jablonski diagram?
Fluorescence. Another pathway for molecules to deal with energy received from photons is to emit a photon. This is termed fluorescence. It is indicated on a Jablonski diagram as a straight line going down on the energy axis between electronic states.
How is Jablonski diagram used in photochemical phenomena?
Jablonski diagrams are used to easily visualize the complex inner workings of how electrons change eigenstates in different conditions. Through this simple model, specific quantum mechanical phenomena are easily communicated.
What is the difference between internal conversion and intersystem crossing?
Internal conversion is the radiationless transition between energy states of the same spin state (compare with fluorescence-a radiative process). Intersystem crossing is a radiationless transition between different spin states (compare to phosphorescence).
Why does fluorescence occur?
Fluorescence occurs when electrons go back from a singlet excited state to the ground state. But in some molecules the spins of the excited electrons can be switched to a triplet state in a process called inter system crossing. These electrons lose energy until they are in the triplet ground state.
What causes Stokes shift?
The Stokes shift is primarily the result of two phenomena: vibrational relaxation or dissipation and solvent reorganization. A fluorophore is a dipole, surrounded by solvent molecules. When a fluorophore enters an excited state, its dipole moment changes, but surrounding solvent molecules cannot adjust so quickly.
What is singlet and triplet state?
Singlet state: All electrons in the molecule are spin paired. It is called a singlet because there is only one possible orientation in space. Triplet state: One set of electron spins is unpaired. It is called a triplet because there are three possible orientations in space with respect to the axis.
What causes intersystem crossing?
Intersystem crossing between triplets and singlets arise from spin-orbit interaction. The highest rates are between adjacent states mixed by spin-orbit interaction, and symmetric vibrations absorb the mismatch in energy.