Luminescence is “COLD LIGHT.”Cold light is light that usually occurs at low temperatures. Luminescence can be produced in many different. Bioluminescence, i.e. luminescence generated by a living organism. black body radiation or incandescence from things getting very hot very quickly. Thermoluminescence is an important method for dating some archeological artifacts. Incandescence is light emitted from material because of the high temperature of the material. In a conventional incandescent light bulb, the excited atoms in the.
Types of Luminescence
Or why those plastic stars are still glowing at night after the lights have been switched off? You may not have. However, whether you have asked yourself those questions or not, the following text will hopefully provide you with answers and explanations of the phenomena of glowing bracelets, shining jellyfish, black light, and many more.
Luminescence In general, the glow that occurs in all the aforementioned phenomena is called luminescence.
Luminescence vs. Incandescence | VanCleave's Science Fun
Luminescence is energy released by a substance in the form of light [1,2]. Several types of luminescence can be differentiated: One example is chemiluminescence. During some chemical reactions, energy is released as light. This occurs after bending a glow stick. It is also the reason for the glowing of animals like jellyfish or some microorganisms.
In this case, it is called bioluminescence . Another kind is triboluminescence. This can be observed when a self-adhesive envelope is opened in complete darkness or when adhesive tape is unrolled in a dark room. In doing so, mechanical energy is put into the system and serves as an activator for the glow .
Probably the most familiar type of luminescence is photoluminescence. Here, energy is provided by electromagnetic radiation, for instance through sunlight or an ultraviolet lamp, as in some discotheques.
This causes phenomena like the ongoing glow of plastic stars or the extreme brightness of white clothes under black light.
One can differentiate fluorescence and phosphorescence, which will be explained below . What is an Electronically Excited State? Generally, all kinds of luminescence are based on so-called photo-physical processes. Usually, molecules themselves are described as fluorescent. This is the case with fluorescent dyes like fluorescein or curcumin [1,5].Science - Light
However, to explain photo-physical processes, one has to take a closer look at an even smaller level than the molecular one. Atoms of different elements have a different number of electrons distributed into several shells and orbitals. Electrons are a type of elementary particle. Electronic transitions are responsible for luminescence [6,7].
Luminescence vs. Incandescence
When the system absorbs energy, electrons are excited and are lifted into a higher energetic state. How this works exactly will be explained using photoluminescence as a specific example.
Different energetic states of an atom or molecule are known as "energy levels". Depending on the molecule and atom, the electrons can only occupy discrete energy levels since the energy is quantized, which means, energy can only be absorbed and emitted in certain amounts .
The difference between two levels can be calculated with equation 1 where E2 is the higher energy level and E1 the lower one. Only light with a certain energy, and accordingly with a certain frequency and wavelength, is capable of exciting electrons .
By equalizing equations 1 and 2, and with the help of equation 3 where c stands for the speed of lightthe necessary frequency and wavelength can be calculated see eq.
In many cases, UV-radiation is used for excitation. Electrons drop back to their ground states. At the same time, the excitation energy is released again. Triboluminescence occurs when a material is scratched, crushed, rubbed or stressed mechanically in any way.
When a material is subjected to mechanical stress spatially separated, electrical charges are produced. Since electrical discharge is in the foundation of Triboluminescence, it can be classified as a part of Electroluminescence. Blue or red Triboluminescence can be observed when sawing a diamond during the cutting process.
Crystalloluminescence is a type of Luminescence generated during crystallization, used to determine the critical size of the crystal nucleus. Separation of electrical charges may occur on the fracture facets on the surface of micro-fractures and their following recombination.
This effectively classifies Crystalloluminescence as a type of Triboluminescence and a subtype of Electroluminescence. Let us note that electrically charged micro-fractures may be developed due to multiple processes such as the movement of charged dislocations, piezoelectrification, etc.
Sonoluminescence is the emission of short bursts of light from imploding bubbles in a liquid when excited by sound. It is believed that when a bubble starts imploding, extremely high pressures inside the bubble cause the water to form ice-like structures. At the moment when the opposite sides of an imploding bubble collide, the very strong mechanical stress causes the ice to fracture.
The growth of ice micro-fractures results in separation of electrical charges and their following recombination, which generates light. Therefore, Sonoluminescence is a part of Triboluminescence phenomenon. It is emitted at relatively short wavelengths, which can reach into the ultraviolet. The emitting bubble size is averaged at about 1 mkm in diameter. The addition of a small amount of noble gas such as helium, argon, or xenon to the gas in the bubble enhances the intensity of the emitted light dramatically.
Chemoluminescence is conversion of chemical energy directly into light as a result of a chemical reaction. In brief, given reactants A and B are transformed into an excited intermediate I. The decay of the excited intermediate I to a lower energy level is responsible for the emission of light. Fluorescence and Photoluminescence are luminescence where the energy is supplied by electromagnetic radiation rays such as light, which will be discussed later.
Photoluminescence is generally taken to mean "luminesce from any electromagnetic radiation", while fluorescence is often used only for luminescence caused by ultraviolet, although it may also be used for other photoluminescences.
Fluorescence is seen in fluorescent lights, amusement park and movie special effects, the redness of rubies in sunlight, "day-glo" or "neon" colors, and in emission nebulae seen with telescopes in the night sky. Bleaches enhance their whitening power with a white fluorescent material. Photoluminescence should not be confused with reflection, refraction, or scattering of light, which cause most of the colors you see in daylight or bright artificial lighting.
Photoluminescence is distinguished in that the light is absorbed for a significant time, and generally produces light of a frequency that is lower than, but otherwise independent of, the frequency of the absorbed light. Chemiluminescence is luminescence where the energy is supplied by chemical reactions.
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Those glow-in-the-dark plastic tubes sold in amusement parks are examples of chemiluminescence. Bioluminescence is luminescence caused by chemical reactions in living things; it is a form of chemiluminescence. Fireflies glow by bioluminescence.
Electroluminescence is luminescence caused by electric current. Cathodoluminescence is electroluminescence caused by electron beams; this is how television pictures are formed on a CRT Cathode Ray Tube.
Other examples of electroluminescence are neon lights, the auroras, and lightning flashes. This should not be mistaken for what occurs with the ordinary incandescent electric lights, in which the electricity is used to produce heat, and it is the heat that in turn produces light.
Radioluminescence is luminescence caused by nuclear radiation.