What is fluorescence?
Fluorescence is the name for the absorption of light at one wavelength and its re-emission at another wavelength. What that boils down to is that some things will glow when you shine the right light on them. The ‘right light’ can be different for different targets. We are most used to seeing fluorescence produced by ultraviolet light, often called ‘black light’ because we humans can’t see it. At NightSea we mostly deal with specially filtered blue lights, because the blue has proved to be better at making most things underwater fluoresce. Fluorescence is kind of magical. You point one light at a target and a totally different color comes out. One of the characteristics of fluorescence is the intense, highly saturated colors. We are used to seeing things illuminated by white light, which contains all the colors of the spectrum. When something fluoresces it usually emits only a narrow range of colors, making it appear like a pure color. There are fluorescent items around you all the time
Fluorescence is the phenomenon in which absorption of light of a given wavelength by fluorescent molecule is followed by the emission of light at longer wavelengths. The distribution of wavelength-dependent intensity that causes fluorescence is known as the fluorescence excitation spectrum, and the distribution of wavelength-dependent intensity of emitted energy is known as the fluorescence emission spectrum.
Fluorescence was first observed as long ago as 1565 and gets its name from a type of naturally occurring mineral, Fluorspar (Fluorite), which glows under ultra violet (UV) irradiation. Fluorescence is a photo-luminescence phenomenon, meaning a molecule can emit energy in the form of visible light after it has been irradiated with a radiation source that is not visible. When a material that is capable of fluorescing is irradiated with UV radiation, the absorbed energy forms an unstable state in the molecule that stabilizes itself by spontaneously emitting excess energy at a different wave-length, which we see as fluorescence. This can be observed as various colors depending on the emission wave-length – from deep blue, violet, green and even shades of yellow (see Figure 1). As soon as the UV radiation source ceases, fluorescence also ceases. Figure 1: Fluorescence Emission Colors and Relative Intensities of Regalite Partially Hydrogenated Hydrocarbon Resins with Varying Degrees of Hydro
Fluorescence is an optical phenomenon that is manifested as glowing light. We observe it every day in the energy-saving compact fluorescent light bulbs that are used in many household and glow sticks that are often used in emergency situations, but in nightclubs as well. Fluorescence is often referred to as “cold light,” because very little heat is emitted by most fluorescent substances. This is very different from incandescent light, the type of light that is found in traditional light bulbs that is emitted due to high temperatures. Another phenomenon that is very similar to fluorescence is phosphorescence. In both cases, cold light will be emitted when the light-emitting object is exposed to an external energy source. However, fluorescence differs from phosphorescence in that the fluorescent light ceases immediately after the energy source is removed, while a phosphorescent light will continue glowing for some time after. The phenomenon of fluorescence occurs when a high energy photo
