Practice question

Fluorescence process visualized by Jablonski diagram begins with photon absorption promoting ground state S0 to singlet excited S1 or S2, followed by ultrafast internal conversion and vibrational relaxation to lowest vibrational level of S1. Emission originates from this level to ground S0. Energy lost non-radiatively during relaxation and solvent reorientation around excited dipole reduces emission energy relative to excitation, causing longer wavelength. This difference defined as Stokes shift arises from non-radiative dissipation as heat before photon emission. Magnitude influences choice of filter sets, sensitivity and separation of excitation and emission in fluorescence spectroscopy and microscopy.