fluorescence

IPA/fləˈresns/
KK[flˌʊrˈɛsəns]IPA/fləˈresns/

fluorescence — noun

1. a bright, visible glow given off by certain materials when they take in energy f

1.nounC1
Definition

a bright, visible glow given off by certain materials when they take in energy from a shorter-wavelength light source, such as ultraviolet radiation — the glow stops almost as soon as the source is removed

Example

Cyrus was amazed by the bright green fluorescence of the mineral under ultraviolet light.

visible light + UV source collocation

Beatrix watched the jellyfish's fluorescence glow a vivid blue in the dark seawater.

marine organism producing fluorescence

Common collocations
  • bright fluorescence
  • green / red / blue fluorescence
  • ultraviolet fluorescence
  • under UV light
Synonyms
  • luminescence

    broader term covering any cold-light emission not caused by heat; fluorescence is one type of luminescence

  • phosphorescence

    similar but delayed emission that continues after excitation stops, unlike fluorescence which is immediate and brief

  • bioluminescence

    light produced by living organisms through a chemical reaction, not by absorbing external light

Grammar Patterns

fluorescence + of + noun phrase

noun + fluorescence

Usage Note

Uncountable; used mainly in scientific or technical contexts. The effect ceases within nanoseconds of removing the energy source — this distinguishes fluorescence from phosphorescence, which continues to glow.

Common Mistakes

The fluorescence of the stone kept glowing for ten minutes after the UV lamp was switched off.
The fluorescence stopped as soon as the UV lamp was switched off.
Fluorescence ends almost instantly when the energy source is removed; a glow that lasts minutes is phosphorescence.

2. the physical property of a substance that causes it to absorb short-wavelength r

2.nounC1
Definition

the physical property of a substance that causes it to absorb short-wavelength radiation and immediately release it as longer-wavelength visible light

Example

Joshua tested the fluorescence of several diamonds by shining a UV torch on them.

diamond fluorescence under UV test

The strong fluorescence of this plastic makes it useful for safety signs in dark buildings.

practical application in safety materials

Common collocations
  • strong / weak fluorescence
  • exhibit fluorescence
  • measure fluorescence
  • fluorescence intensity
Synonyms
  • luminescence

    broader property of emitting light without heat; fluorescence is a specific subtype with immediate emission

  • phosphorescence

    similar light-emitting property but with a delayed, longer-lasting glow after the source is removed

Grammar Patterns

fluorescence + of + noun

noun + shows / exhibits + fluorescence

Usage Note

Uncountable; describes a material characteristic rather than the light itself. Frequently appears in materials science and analytical chemistry contexts: 'the fluorescence of [substance]'.

Common Mistakes

This ink has fluorescence colour.
This ink shows strong fluorescence.
Fluorescence is a property, not a colour; use 'shows / exhibits / has' + 'fluorescence'.

Word family

  • fluoresce
    verbC1
  • fluorescent
    adjectiveB1
  • fluorophore
    nounC2
  • fluorimetry
    nounC2

Synonym discussion

Sense: noun/1

Fluorescence, luminescence, phosphorescence, and bioluminescence all describe the emission of light from a substance, but they differ in mechanism and duration. Luminescence is the broadest category — any emission of cold light that is not caused by heat. Fluorescence is a specific type of luminescence in which the glow stops almost instantly (within nanoseconds) when the energy source is removed; it typically involves ultraviolet light being converted into visible light. Phosphorescence is similar, but the material stores the energy and releases it slowly, so the glow can continue for seconds or even hours after the source is turned off. Bioluminescence is a special case in which light is produced through a chemical reaction inside a living organism, such as a firefly or a deep-sea fish. For example, the bright mark on a fluorescent highlighter fades the moment you remove the UV light (fluorescence), whereas the glow-in-the-dark stars on a bedroom ceiling keep shining for a while (phosphorescence).

luminescence ↗phosphorescencebioluminescence ↗

Common collocations

Nouns

Adverbs

Phrases

  • under ultraviolet light
  • under a black light
  • UV-induced fluorescence

Prepositions

  • under (UV light / black light)
  • of (a substance / a mineral)

Etymology

LatinEnglish

The word comes from the mineral fluorite (calcium fluoride), which was one of the first substances in which the effect was observed. The mineral's name comes from Latin 'fluere' (to flow), referring to its use as a flux in metal smelting. The suffix '-escence' means 'a process or state of becoming'. The term 'fluorescence' was coined by Irish physicist Sir George Stokes in 1852.