Microscopy and Fluorescence
3 types of microscope: Brightfield (most common), Darkfield, Fluorescence
Fluorescence: ability to absorb electromagnetic radiation at a certain wavelength and to emit a fraction of the energy absorbed as radiations of a different and longer wavelength.
The energy of light absorbed by an object is dissipated as heat or light of a different colour (different frequency or wavelength); in the case of UV, the rays excite the material which reacts emitting fluorescent light.
Fluorescent materials cease to be bright as soon as the light source stops to work.
The fluorescence can be direct (from a fluorescent material) or indirect (from a non fluorescent material contaminated with chemicals).
(From lectures of Università Statale of Milan and Pavia, faculty of Pharmaceutical Chemistry and Biotechnologies)