Luminescence
LUMINESCENCE is known as the emission of light by a substance that has not been heated. This phenomenon occurs when a photon is absorbed and subsequently causes an electron to jump from its ground state to a higher (more excited) energy state.
Around 0.00000001 seconds later, the electron returns to the ground state which results in the emission of a photon and an excited vibrational state which reaches equilibrium approximately 0.000000000001 seconds later.
LUMINESCENCE can be the result of many reactions, including chemical, biochemical, subatomic particle activity, radiation, or additional stress added to a crystal.
Types of Luminescence
Photoluminescence- a process which occurs when moving electrons travel to higher energy levels through the absorption of photons
Thermoluminescence- the phenomenon that occurs when a crystalline material is heated and gives off light that is not black body radiation or incandescence
Sonoluminescence- occurs when a liquid is excited by sound and emits short bursts of light from bubbles
Crystalloluminescence- can potentially occur during crystallization as a result of bonding between atoms.
And most importantly....
Chemiluminescence- occurs as a result of chemical or electrochemical reactions. Few chemical reactions result in luminescence as the return to the ground state generally releases energy in another way (ie. as heat) rather than visible light
--> Bioluminescence- Bioluminescence is the process of chemiluminescence carried out by living organisms as a survival mechanism. This requres a reaction betweeen a particular chemical and oxygen gas.