Photochemistry: A Jablonski Diagram

Summary:
An electron can absorb energy and move to a higher energy orbital. From here energy of the electron can be lost in several ways. The electron can relax through vibration or rotation in the same electronic state. If such relaxation occur between electronic states it is called Internal Conversion (IC). Fluorescence sees some of the energy lost as a photon and the electron energy drops between electronic states. Inter-system Crossing (ISC) has th electron change spin state from singlet to triplet. From there the electron can return to a single state, ground state energy with phosphorescence. These processes take increasingly longer time to carry out.

Key Words:
Absorbance, Relaxation, Vibration, Rotation, Internal Conversion (IC), Electronic State, Fluorescence, Inter-System Crossing (ISC), Phosphorescence