Final answer:
Fluorescence is the process through which excitation light makes a fluorophore glow. High-energy photons excite electrons, which then release lower-energy photons as they return to the ground state, emitting light that is visible as glowing.
Step-by-step explanation:
Excitation light makes a fluorophore glow through a process known as fluorescence. When a fluorophore absorbs high-energy ultraviolet (UV) photons, an electron is excited to one of the molecule's higher energy levels. This state is not stable, so the excited electron then returns to the ground state. Instead of releasing a single photon with the same energy that was absorbed, the electron can de-excite in a series of smaller steps. Each step can release a photon, often of lower energy, resulting in light that has a longer wavelength than the UV light absorbed. This emission of low-energy photons, some of which may be in the visible range, is what we observe as glowing.
Fluorophores can become repeatedly excited and emit light, which is utilized in fluorescent lights. These lights convert electrical energy to visible light efficiently by exciting electrons in molecules on the bulb's interior surface. As the electrons calm back to the ground state, they fluoresce, making the light glow. Fluorescent substances interact with UV radiation to appear brighter in sunlight—a phenomenon seen with fluorescent dyes in clothing.
Common fluorescent lights and specialized equipment like spectrofluorometers leverage this process to generate or measure light in various scientific applications. The fluorescence process allows for the transformation of various forms of energy into visible light which can be adapted for different needs and is integral to the fields of biochemistry, molecular biology, and microscopy.