How does a fluorophore become excited?
1 Answer
A light source with the appropriate wavelength raises the electrons in the fluorochrome to a higher energy electronic orbital.
While the electron is in the higher state (usually 1 to 10 ns), it can undergo non-radiative transitions in which the energy is dissipated as heat (vibrations) to the solvent.
When the electron decays from its exited state, it has less energy than it had originally absorbed, so the wavelength of the emitted fluorescent light is longer than that of the absorbed light.
Each fluorochrome has a characteristic spectrum for absorption and fluorescence.
The fluorochrome above is excited by blue light and fluoresces in the greenish-yellow region.
Usually a fluorochrome is a dye that binds to the macromolecules in cells to form a fluorophore.
You are really measuring the fluorescence of the fluorochrome.
