The light made in chemiluminiscence is not directly related to heat. A simple two step example of a reaction of A, and B, that produces; C, D, and light.
- [A] + [B] → [C*] + [D]
- [C*] → [C] + [Light(hν)]
C* is an excited state of C.
This reaction is simpler than most chemiluminesence reactions. The excited state happens when electrons are pushed into a higher orbit by the energy of a chemical reaction. The excited state is less stable than the ground state. The electrons in the excited state fall to the ground state (lower energy), emitting light.
Analytical applications[change | edit source]
The device needed to measure the light made is simple. It needs something to hold the sample, and a photomultiplier tube. There are three ways for this to be used in chemical measurements.
- sometimes the product wanted makes light when it reacts with another compound,
- in another type the amount of light made drops when the wanted product is added,
- sometimes the wanted product when added to a chemiluminescence reaction makes more light(a catalytic reaction).
Analysis of gases[change | edit source]
The method measures small amounts of atmospheric pollutants. A common method measures the amount of nitrogen monoxide by reacting it with ozone. The light made has a wavelength range of 600 to 2800 nm.
Analysis of liquids[change | edit source]
Luminol is the most well known type of compound used for chemiluminescence in liquids.
Analysis of cell organelles[change | edit source]
Ca2+(calcium) inside of different parts of cells like the mitochondria can make light when it reacts with a protein from jellyfish named aequorin. Nitric oxide(NO) is in cells and is a way for cells to talk to each other, this can be measured with the compound luminol.
Other examples[change | edit source]
- An example of chemiluminescence molecules in nature is firefly luciferin.
- The process is used to make glowsticks.
References[change | edit source]
- Daniel C. Harris. In Quantitative Chemical Analysis Seventh Edition: 2007 by W.H. Freeman and Company.
- Douglas A. Skoog, James F. Holler, Stanley R. Crouch. In Principles of Instrumental Analysis Sixth Edition:2005 by Thomson, Brooks, Cole.