Fluorescence
Fluorescence is the property of some molecules to absorb light at one wavelength and reemit it at a longer wavelength. This process is known as fluorescence, and it occurs when an electron in the molecule is excited from a ground state to a higher energy state by the absorption of a photon. The excited electron then relaxes back to its ground state, releasing energy in the form of a new photon with a longer wavelength [American Chemical Society].
Fluorescence is a common phenomenon that can be observed in a wide range of materials, including minerals, liquids, and gases. It is also widely used in scientific research, medical diagnostic tools, and many other applications. For example, fluorescence microscopy is a powerful technique in biology that allows researchers to visualize the structure and function of cells and tissue in great detail [National Institutes of Health].
In chemistry, fluorescence spectroscopy is a widely used technique for analyzing chemical compounds, enabling the detection and identification of molecules at deficient concentrations [American Chemical Society].
In addition to its many practical applications, fluorescence also has a rich history. The phenomenon was first observed in the early 19th century by French scientist George G. Stokes, who discovered that certain substances emit light when excited by light of a shorter wavelength [Stokes]. This observation laid the foundation for developing fluorescence spectroscopy and other fluorescence-based techniques.
https://www.acs.org/content/acs/en/analytical-chemistry/spectroscopy/fluorescence-spectroscopy.html.
https://www.nigms.nih.gov/education/pages/factsheet_fluorescencemicroscopy.aspx.
Stokes, G. G. (1852). On the change of refrangibility of light. Transactions of the Cambridge Philosophical Society, 9, 399-416.