Fluorescence and Phosphorescence
Fluorescence and phosphorescence are two ways in which materials emit light. Both processes
start by absorbing energy, which excites electrons in the material. Then, the energy is released as
light. The main difference between these two phenomena is the amount of time it takes for the
energy to be released and the type of energy involved.
Fluorescence occurs immediately after the material absorbs energy in the form of light. The
excited electrons quickly release the absorbed energy as light, producing a glow or color. This
happens within a few nanoseconds.
Phosphorescence, on the other hand, happens when the material absorbs energy and holds onto it
for a longer period before releasing it as light. This delayed release is due to the presence of
triplet excited states, which can persist for several milliseconds or even seconds before emitting
light. This causes phosphorescent materials to continue glowing even after the source of
excitation has been removed.
The energy involved in fluorescence and phosphorescence is different. Fluorescence typically
involves energy in the ultraviolet or visible range, while phosphorescence can also involve
energy in the infrared range. Both organic molecules and certain inorganic compounds, like
transition metal complexes, can exhibit fluorescence and phosphorescence.
In summary, fluorescence and phosphorescence are two related but distinct ways in which
materials emit light. Fluorescence happens almost immediately, while phosphorescence has a
delayed release of energy. Both processes involve the interaction of electrons with energy from
the electromagnetic spectrum. Organic molecules and certain inorganic compounds are known to
display fluorescence and phosphorescence.
References:
Kamal, C., & Bhattacharjee, A. (2019). Fluorescence and phosphorescence. In Principles of
Organic Light Emitting Diodes (pp. 23-44). Springer, Singapore.
Nakamura, N., & Yamamoto, Y. (2018). Fundamentals and applications of phosphorescence.
Chemical Society Reviews, 47(14), 5298-5316.
Wang, X., Liu, X., Xu, W., & Zhang, J. (2020). Recent advances in molecular materials for
thermally activated delayed fluorescence and phosphorescence. Materials Chemistry Frontiers,
4(7), 1973-1995.