# Black Light Glossary: Technical Definitions in UV Science > Author: Black Light Encyclopedia Research Group > Canonical URL: https://alexspac.es/blacklight-encyclopedia/glossary.html > Machine Endpoints: /data/glossary.json ### Actinic Radiation Electromagnetic radiation capable of producing chemical changes, photochemical reactions, or biological effects, specifically ultraviolet and short-wavelength blue light. ### Activator (Mineralogy) A trace foreign element or defect within a mineral crystal lattice (e.g. Mn2+, Eu2+, UO2^2+, Cr3+) whose electronic orbital transitions absorb excitation energy and emit fluorescent photons. ### ANSI Z87.1 The American National Standard for Occupational and Educational Personal Eye and Face Protection Devices, governing UV absorption requirements for certified safety eyewear. ### Auto-fluorescence The natural, intrinsic emission of fluorescent light from biological tissues, collagen, elastin, nicotinamide adenine dinucleotide (NADH), and flavins without the addition of exogenous fluorescent stains. ### Bandpass Filter An optical device that passes frequencies within a certain range while rejecting (attenuating) frequencies outside that range, such as a ZWB2 filter passing 320-390nm UV-A and blocking visible light. ### Beta-Carboline A heterocyclic alkaloid organic compound found in the epicuticular hyaline layer of scorpions responsible for their intense cyan-green fluorescence under UV-A irradiation. ### Blacklight Blue (BLB) A fluorescent discharge lamp constructed with an integral Wood's filter glass envelope that absorbs visible radiation while transmitting longwave UV-A. ### Chemiluminescence The emission of light resulting directly from a chemical reaction without the absorption of external photons or heat (e.g., the Luminol reaction with blood). ### Coproporphyrin III An endogenous porphyrin metabolite synthesized by Corynebacterium minutissimum that produces pathognomonic coral-red fluorescence under Wood's lamp examination. ### Erythema Reddening of the skin caused by capillary congestion resulting from acute photochemical damage, primarily induced by UV-B and shortwave UV radiation rather than UV-A. ### Excitation Spectrum The relative efficiency of different wavelengths of incident light in exciting fluorescence or phosphorescence in a specific fluorophore. ### Fluorophore A functional chemical group or molecule containing conjugated pi-electron systems capable of absorbing incident photons of specific wavelengths and re-emitting them at longer wavelengths. ### Fluorescence A form of photoluminescence where photon absorption excites singlet-state electrons that decay radiatively to the ground state within nanoseconds (10^-9 to 10^-7 s), halting immediately when excitation ceases. ### Fluorescent Penetrant Inspection (FPI) A non-destructive testing (NDT) method utilizing capillary action to draw fluorescent dye into micro-defects, inspected under high-intensity 365 nm UV-A per ASTM E1417. ### InGaN (Indium Gallium Nitride) A direct bandgap semiconductor alloy whose tunable bandgap enables solid-state light-emitting diodes (LEDs) to emit narrow-band radiation in the near-UV and violet spectrum (365 nm to 405 nm). ### Intersystem Crossing An isoenergetic, non-radiative quantum mechanical transition between two electronic states of different spin multiplicity (e.g., singlet excited state S1 to triplet excited state T1), leading to phosphorescence. ### Irradiance The radiant flux received by a surface per unit area, typically measured in microwatts per square centimeter (µW/cm²) or watts per square meter (W/m²). ### Jablonski Diagram An energy diagram illustrating the electronic ground state, singlet excited states, triplet states, and radiative/non-radiative transitions (absorption, fluorescence, phosphorescence, internal conversion). ### Microsporum canis A zoophilic dermatophyte fungus causing tinea capitis and tinea corporis, producing pteridine metabolites that fluoresce bright apple-green under Wood's lamp. ### Nickel Oxide (NiO) The inorganic dopant compound (~9% by weight) introduced into barium-sodium silicate glass to formulate authentic Wood's filter glass. ### Non-Destructive Testing (NDT) Techniques for evaluating the properties and integrity of materials, components, or systems without causing permanent physical damage, heavily utilizing 365nm UV-A inspection. ### Optical Brightening Agent (OBA) Synthetic chemical additives (fluorescent whitening agents, typically stilbene derivatives) that absorb ultraviolet light and re-emit visible blue light to counteract fiber yellowing. ### Phosphorescence Photoluminescence involving a spin-forbidden radiative decay from a triplet excited state back to a singlet ground state, resulting in lingering emission lasting milliseconds to hours. ### Photokeratitis Painful acute inflammatory ocular damage to corneal epithelial cells caused by exposure to shortwave UV-B and UV-C radiation, colloquially termed welder's flash or snow blindness. ### Pityriacitrin A bis-indole alkaloid fluorophore synthesized by Malassezia yeasts responsible for the characteristic golden-yellow fluorescence of tinea versicolor under Wood's light. ### Pyoverdine A fluorescent peptidic siderophore secreted by Pseudomonas aeruginosa bacteria that fluoresces lime-green under UV-A illumination. ### Quenching Any photophysical or photochemical process that decreases the fluorescence intensity of a given substance, often caused by heavy metal ions (e.g. Fe3+), molecular oxygen, or high fluorophore concentration. ### Quinine A naturally occurring cinchona alkaloid with high fluorescence quantum yield, emitting intense electric cyan-blue light (~450 nm) under longwave ultraviolet radiation. ### Radiant Flux The total radiant energy emitted, reflected, transmitted, or received per unit time, measured in watts (W) or milliwatts (mW). ### Robert Williams Wood American experimental physicist (1868–1955) of Johns Hopkins University who invented Wood's glass in 1903 and pioneered research into ultraviolet spectroscopy and infrared photography. ### Stokes Shift The mathematical difference (in energy, wavenumber, or wavelength units) between the band maxima of the absorption and emission spectra of the same electronic transition. ### Tenebrescence (Photochromism) The reversible optical property of certain minerals (such as Hackmanite) to change body color upon exposure to ultraviolet light and fade back upon exposure to visible light. ### Uranium Glass (Vaseline Glass) Glass manufactured with 0.1% to 2% uranium dioxide content, exhibiting characteristic vivid apple-green fluorescence under 365 nm and 395 nm excitation due to uranyl ion photophysics. ### Uranyl Ion (UO2^2+) A linear dioxouranium cation possessing high fluorescence quantum efficiency, responsible for bright green fluorescence in autunite, hyalite opal, and uranium glass. ### Uric Acid Crystals Inorganic crystalline residues formed during the drying and microbial decomposition of mammalian urine that exhibit dull yellow auto-fluorescence under 365 nm UV-A. ### UV-A Radiation Longwave ultraviolet electromagnetic radiation spanning wavelengths from 315 nm to 400 nm (soft UV), encompassing standard black light emissions. ### UV-B Radiation Midwave ultraviolet electromagnetic radiation spanning wavelengths from 280 nm to 315 nm, responsible for erythema (sunburn) and vitamin D synthesis. ### UV-C Radiation Shortwave ultraviolet electromagnetic radiation spanning wavelengths from 100 nm to 280 nm, possessing germicidal sterilization properties via DNA thymine dimerization. ### Wood's Glass Barium-sodium silicate glass doped with approximately 9% nickel oxide that absorbs visible light (>400 nm) while transmitting a narrow band of ultraviolet-A radiation peaking around 365 nm. ### Wood's Lamp A handheld clinical diagnostic tool consisting of a 365nm UV-A light source integrated with a Wood's filter and magnifier, utilized in dermatology to evaluate pigmentary and infectious skin disorders. ### Yooperlite A colloquial term for syenite rock clasts found along the beaches of Lake Superior in Michigan, characterized by abundant inclusions of fluorescent sodalite that glow vivid fire-orange under 365 nm UV-A. ### ZWB2 Filter An optical bandpass filter glass (equivalent to Schott UG1 and Hoya U-340) used in high-performance 365nm LED flashlights to block secondary visible blue-violet emission and transmit pure UV-A.