Chemiluminescence

__**//Geoff Klein//**__ __ Chemistry Of Chemiluminescence __

Chemiluminescence is the term used for light created by atoms emitting photons from a reaction. It is also known as cool-light because unlike other forms of like, like incandescent light that emits a lot of heat. Chemiluminescence is a very simple concept in terms of chemistry. It can happen two ways. The first way is when two molecules react. Energy is transferred into the product’s molecules. This excites the electrons in the product molecules, and they jump up to the next orbital. Once they fall down and the electrons that were excited return to ground state, photons are released. The colour and frequency of the photon depends on the orbital the valence electron jumped up to; whatever colour and frequency that orbital represents, that colour and frequency is released.

The second way chemiluninescence can happen is very similar to the first way. This is way that glow sticks work. This way involves a reaction that has energy released as a product. The energy is then transferred in a fluorescent dye, and its electrons are jumped to excited state. When it falls to ground state, photons are released for the specific orbital it was jumped to. This method is used so that no matter what chemicals or molecules are used to produce the energy, the energy is always transferred to the same fluorescent dye. It will always produce the same colour.

Now, as simple as this seems, this is only the basis. Most reactions are not this simple and involve more than one reaction. The starting and end is always the same, but there can be multiple reactions in the process and multiple molecules used.

Most chemiluninescent reactions involve electrons being transferred. The electron transfer has nothing to do with the energy being transferred. This means that even if a product has electrons gained, if does not mean for sure that it ha s energy gained. It could, but that cannot be known just from electron transfer. Since electrons are being transferred, these are **redox** reactions. Electrons are lost, **oxidation**, and then gained, **reduction**. This comes in if there are multiple reactions that take place, or even just one reaction.

__ Applications __

Chemiluminescence has had many applications and has become an effective tool in a lot of areas. One of the more common examples is the //Glow Stick// that is used for many reasons. They were invented by the US Navy for special OP missions as a portable light that can b e shielded easily. It is also used as a navigational tool for divers in muddy waters. It is very effective because it is the only light that does not use electricity and is easily portable.

Chemiluminescence is also used in nature. An example of this is the male fire fly that uses the light to attract females to mate. When chemiluminescence is used in living things, it is called **bioluminescence**. They use a luciferin substrate and an enzyme together with oxygen and adenosince triophosphate (ATP) as the energy source. This reaction is what gives them their glow. Now, this might be used to attract mates, but it is not the most effective way of doing it. Not only will this attract mates, but a bright glow can also attract predators.

Another way chemiluminescence is used in our life is to detect the concentration (parts per billion) of nitrogen dioxide in out atmosphere, NO2. Luminol (3-aminophthalhydrazide), C8H7N3O2, is a chemical that detects the amount of NO­2 in our atmosphere. Luminol chemiluminescence is the reaction of luminol with water and nitrogen gas, N2(g). This reaction causes the triple bonds of nitrogen gas to break, **N­ N**­, which releases a high amount of energy. The product is aminophth alate anion in an excited state with the energy released from the nitrogen gas triple breaking. This is an **oxidation** reaction where electrons are lost. Chemiluminescence with Luminol has many reactions, like the one above. Another reaction of Luminol is the detection of blood in crime scenes. All the chemicals are mixed in a spray bottle and when sprayed on the blood, it lights up so forensics and other officers can try to determine what happened at a possible crime scene. Luminol is mixed with hydrogen peroxide and a hydroxide salt, like potassium hydroxide KOH. When they are sprayed, the iron in the blood acts as a catalyst and causes the reaction. The blood will glow making it possible to see where the blood is. It glows blue for about 30 seconds, which is long enough for skilled photographers to

take the pictures of the crime scene.

__ Demonstration __ The detection of blood is possible to try. The all that is needed is Luminol, hydrogen peroxide, a hydroxide salt and iron compound for a catalyst. The catalyst is most often potassium ferricyanide, K6Fe(CN)6. The reation causes the hydrogen peroxide to decompose into water and oxygen gas.

2 H2O2 (aq) -> O2 (g) + 2 H2O (l)

The hydroxide can be 3% concentration, which is the normal //over the counter// solution. The Luminol hydroxide salt solution is composed of, by mass of 2g of Luminol with 15g of the hydroxide salt (potassium hydroxide) and 250mL of water. The reaction is pretty simple once all the materials are collected. Add 10mL of the Luminol hydroxide salt with 10mL of the hydrogen peroxide in either a beaker or a test tube. Now, the potassium ferricyanide is added. For this reaction, approximately 0.1g is all that is needed to get the blue glow. Another way also is have the 10mL of both the hydrogen peroxide and Luminol hydroxide salt in separate test tubes. Dissolve the potassium ferricyanide in the hydrogen peroxide. Then, add both solutions in an empty beaker to see the reaction.

Not all of these chemicals are also needed for this experiment to work, and some can be switched with others. A copper compound can be used rather than an iron compound. Or, to get real exact, you can use dried blood on a sterile alcohol pad. Extra precaution is needed when using blood. Horse radish can also be used as a catalyst. Mimi Duarte

**Chemiluminescence and Bioluminescence**
==In general, bioluminescence refers to the biological process of creating visible light through biological systems == It is a subset of chemiluminescence because it relates to the production of light through a chemical reaction; the only characteristic that separates the two is that the reaction requires an enzyme catalyst and actually occurs within an organism.



**The Chemistry Behind Bioluminescence**

A wide variety of organisms can produce light. However the chemical reaction that creates bioluminescence is generally the same in each of these organisms. It is a complex one that involves the combination of two specific chemicals; luciferin and luciferase. The first is luciferin which is a pigment and the chemical that actually produces the light. There are varying types of luciferin in different species of organism, but they all generally operate in the same fashion. Most often, luciferin enters the system through either a particular diet or internal synthesis. Luciferin on its own works by attaching itself to an oxygen molecule (O2) which will in turn give off light. However, this whole process goes by really slowly therefore the light created is not visible. The second necessary chemical is luciferase. Luciferase is an enzyme that catalyzes or drives the reaction fast enough to make the light emitted visible. Other than just light, the Luciferin-luciferase reaction can also create by-products like inactive oxyluciferin and water. Besides the presence of molecular oxygen, the other/last requirement for bioluminescence to occur is ATP. ATP merely translates to adenosine triphosphate. The ATP is a molecule that stores and transports energy and is found in most organisms. The more ATP present, the brighter the light emitted. In bioluminescence it is the main source of energy.

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Every now and then the pigment protein, luciferin, and the catalyzing protein, luciferase, bind together with the co-factor (the molecular oxygen) to form a single structurecalled a photoprotein. At this point, another co-factor is needed to trigger the bioluminescent reaction. The extra co-factor takes the form of an ion and is most frequently a calcium ion (Ca2+). When that ion attaches to the photoprotein it becomes an apoprotein and produces light. On a chemical level, the above luciferin-luciferase reaction drives an electron to a higher energy level temporarily. When it drops back down (because it has to eventually) a photon of light is released. Barely any heat has been let off in the meantime. This shows that bioluminescence is a subset form of chemiluminescence. ======



**__Luciferins __**

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Throughout the many luminous organisms on the earth, there are only a few common luciferin types widespread. This could potentially be the result of similar specific diets among these species. However studies have shown that internally these organisms are capable of producing the exact same type of luciferin as eachother.The four main types of luciferin found in bioluminescent organisms are bacterial luciferin, dinoflagellate luciferin (derived from chlorophyll), vargulin, coeleterazine (most common among marine organisms), and the firefly luciferin. The firefly luciferin actually an organic compound with a chemical formula of C13H12N2O3S2 and requires ATP as a co-factor for its photprotein. Because of this it is used as an indicator life through the presence of energy. ======

**Physical Properties of Bioluminescence**

Similar to the way chemiluminescence spectroscopy detects, bioluminescence operates much the same way. However unlike the atomic emission spectra (AES), both involve emission from energized molecules rather than just simply excited atoms.

Most marine light-emissions belong in the blue and green light spectrum because those wavelengths can specifically transmit through sea water most easily. The blue light produced by most marine bioluminescent organisms range between 440-480 nm. Meanwhile the green light can fair around 500nm. However other colours are not unheard of. <span style="font-family: 'Trebuchet MS',sans-serif; line-height: 14px;">Certain loose-jawed fishes are capable of emitting red and infrared light as well as the entire genus Tomopteris emits yellow. Along with colour variations, bioluminescent light-emissions can differ in brightness and duration. Although the brightness of the light directly depends on the amount of energy being put in the reaction, the luminescence of a single, microscopic dinoflagellate is still visible to the human eye. This can be explained by the different types of luciferins mentioned earlier. The dinoflagellate luciferin is chlorophyll based meaning its energy source is not relevant to ATP molecules, but rather the energy from the sun. Therefore the intensity of luminescence created by photosynthetic dinoflagellates is directly influenced by the amount of sunlight it receives. The brighter the sunlight, then the brighter the glow. Some organisms can emit light continuously while most others are seen in random spurts or flashes (ranging from 0.1s to 10s). This characteristic can just be a result of whatever initially triggers the chemical reaction. Neurological transmitters are the cause of the flashing luminescence. In other instances, bioluminescence is triggered mechanically by the deformation of the cell surface by minute forces. In a phenomenon called “empathetic luminescence” marine organisms with light receptors/eyes the bioluminescence can be induced merely photic excitation, even from another luminescent organism nearby! They are generally referred to as flashlight fish.

<span style="font-family: Tahoma,Geneva,sans-serif;">**Functions of Bioluminescence (Primarily in Marine Organisms)** <span style="font-family: Tahoma,Geneva,sans-serif;">**Human Engineered Applications of Bioluminescence**

<span style="font-family: 'Trebuchet MS',Helvetica,sans-serif; text-indent: 36pt;">Although bioluminescence seems restricted to bioluminescent organisms, humans see great researching potential from this natural source of light. Bioluminescent organisms have been the target for many studies conducted. The two chemical components of a bioluminescent reaction, luciferin and luciferase, have been harnessed for practical biotechnological purposes. Luciferin systems have been developed for biomedical research involving bioluminescent imaging as well as luciferase systems are widely used in the field of genetic engineering and reporter genes. <span style="font-family: 'Trebuchet MS',Helvetica,sans-serif; text-indent: 36pt;">Meanwhile extended research on symbiosis and quorum sensing is being completed via numerous experimental models of bioluminescence present in the marine invertebrates, particularly the glowing bobtail squid. Besides researching potential, bioluminescence can still find a certain way of applying itself. For example, in many countries, household lanterns are made from ground up fireflies. __<span style="font-family: 'Trebuchet MS',Helvetica,sans-serif; margin-left: 36pt;">Potential Future Engineered Applications __ <span style="font-family: 'Trebuchet MS',Helvetica,sans-serif; margin-left: 36pt;">Some proposed environmentally friendly applications of engineered bioluminescence include: <span style="font-family: 'Trebuchet MS',Helvetica,sans-serif; margin-left: 36pt;">---> Glowing trees (as a result of bioluminescence) to line and light up highway lanes reducing government electricity bills <span style="font-family: 'Trebuchet MS',Helvetica,sans-serif; margin-left: 36pt;">---> Glowing Christmas trees that do not require any sort of electrical wiring and in turn remove any electrical fire hazard <span style="font-family: 'Trebuchet MS',Helvetica,sans-serif; margin-left: 36pt;">---> Agricultural/domestic plants that light up indicating when they need watering <span style="font-family: 'Trebuchet MS',Helvetica,sans-serif; margin-left: 36pt;">---> Detecting bacterial contamination of meats and other foods as well as bacterial species in corpses during autopsy

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<span style="font-size: 1.033em; font-weight: normal; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 5px;">__**Chemiluminescence and Lyoluminescence**__ =====

<span style="margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">Lyloluminescence, like bioluminescence, is another subset form of chemiluminescence. It refers to the light that is emitted when dissolving a solid into a liquid solvent. In most cases, lyoluminescence involves solid samples that have been heavily exposed to radiation then dissolved in water. The radiation is a result of ionizing radiation which just means that electrons have been pulled apart from atoms or molecules (ionizing them) by electromagnetic waves. The total light emitted by the material undergoing this process (referred to as the lyoluminescent intensity) is dependent on radiation doses and its probability of recombination. As well, lyoluminescent intensity can increase if the originaly solution contains a chemiluminescent compound such as Luminol. Lyoluminescent based systems are used in radiotherapy and radio-processing for the sterilization of foods. It can also be applied for the measurement of radical scavenging activity in compounds.

References: [] [] [|http://www.lifesci.ucsb.edu/~biolum/organism/dragon.html] [] [] [] [] []

__ Chemiluminescence Lab Date: __ Collaboration of Geoff, Roger, Derek, Mimi

__Purpose__: How does changing the temperature of the reactants affect the speed and brightness of the reaction?

__Materials__: <span style="font-family: Times New Roman; line-height: 150%; margin: 0cm 0cm 0pt 36pt; text-indent: -18pt;">- 3% hydrogen peroxide, 30mL <span style="font-family: Times New Roman; line-height: 150%; margin: 0cm 0cm 0pt 36pt; text-indent: -18pt;">- 15g of potassium hydroxide <span style="font-family: Times New Roman; line-height: 150%; margin: 0cm 0cm 0pt 36pt; text-indent: -18pt;">- 250mL of distilled <span style="font-family: Times New Roman; line-height: 150%; margin: 0cm 0cm 0pt 36pt; text-indent: -18pt;">- 2g of Luminol <span style="font-family: Times New Roman; line-height: 150%; margin: 0cm 0cm 0pt 36pt; text-indent: -18pt;">- 4 clean 50mL beakers <span style="font-family: Times New Roman; line-height: 150%; margin: 0cm 0cm 0pt 36pt; text-indent: -18pt;">- 3 500mL beakers <span style="font-family: Times New Roman; line-height: 150%; margin: 0cm 0cm 0pt 36pt; text-indent: -18pt;">- 2 hot plates <span style="font-family: Times New Roman; line-height: 150%; margin: 0cm 0cm 0pt 36pt; text-indent: -18pt;">- Ice <span style="font-family: Times New Roman; line-height: 150%; margin: 0cm 0cm 0pt 36pt; text-indent: -18pt;">- 500mL of tap water <span style="font-family: Times New Roman; line-height: 150%; margin: 0cm 0cm 0pt 36pt; text-indent: -18pt;">- 0.3g of copper (II) sulphate <span style="font-family: Times New Roman; line-height: 150%; margin: 0cm 0cm 0pt 36pt; text-indent: -18pt;">- Thermometer <span style="font-family: Times New Roman; line-height: 150%; margin: 0cm 0cm 0pt 36pt; text-indent: -18pt;">- Stop watch

*Safety notes:

<span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt; text-align: justify;">__Procedure__: <span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt 54pt; text-align: justify; text-indent: -18pt;">1) Take one of the 500mL beakers and fill with 250mL of distilled water, 2g of Luminol, and 15g potassium hydroxide. //This is considered the Luminol hydroxide salt solution (Reactant 1)//. <span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt 54pt; text-align: justify; text-indent: -18pt;">2) Pour 10mL of the previous solution into a 50mL beaker. <span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt 54pt; text-align: justify; text-indent: -18pt;">3) Pour 10mL of the 3% hydrogen peroxide into a 50mL beaker. Then add 0.1g of the copper (II) sulfate (Reactant 2). <span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt 54pt; text-align: justify; text-indent: -18pt;">4) Combine the two solution in the 50mL beaker containing the Luminol hydroxide salt solution. <span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt 54pt; text-align: justify; text-indent: -18pt;">5) Take the temperature of the combination of the solutions as well as both reactants. Record time of the light’s duration. <span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt 54pt; text-align: justify; text-indent: -18pt;">6) Record observations of the reaction occurring. <span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt 54pt; text-align: justify; text-indent: -18pt;">7) Repeat steps 2 through 6 with the two 50mL beakers [the Luminol hydroxide salt solution and the 3% hydrogen peroxide/copper (II) sulphate solution] being placed on hot plates before combining. <span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt 54pt; text-align: justify; text-indent: -18pt;">8) Repeat steps 2 through 6 with the two 50mL beakers [the Luminol hydroxide salt solution and the 3% hydrogen peroxide/copper (II) sulphate solution] placed in 500mL beakers of approximately 250mL of ice water each.

<span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt; text-align: justify;">__Observations__: <span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt; text-align: justify;">Reactant 1: <span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt; text-align: justify;">Reactant 2: ||  ||   || <span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt; text-align: justify;">Reactant 1: <span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt; text-align: justify;">Reactant 2: ||  ||   || <span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt; text-align: justify;">Reactant 1: <span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt; text-align: justify;">Reactant 2: ||  ||   ||
 * ** Trial Type ** || ** Temperature ** || ** Duration of Light emitted ** || ** Appearance/ Brightness ** ||
 * <span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt; text-align: justify;">Room temp. || <span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt; text-align: justify;">Products:
 * <span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt; text-align: justify;">Ice Water || <span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt; text-align: justify;">Products:
 * <span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt; text-align: justify;">Hot Plate || <span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt; text-align: justify;">Products:

<span style="display: block; font-family: 'Times New Roman'; line-height: 150%; margin: 0cm 0cm 0pt; text-align: justify;">__Analysis__:

**__ References __**

[] [] [] []

__**//Roger Blahut//**__

**__ Electrochemiluminescence __**

==== Electrochemiluminescence is the process of light produced from a chemiluminescent preceding through an electrochemical reaction on an electrode. The reaction uses Ruthenium in either liquid or solid formation, and then processes it through the antibody immunoassay, which can then be sent through electrodes and “tagged” onto DNA probes, NADH molecules or Hydrogen Peroxide to produce the reaction. **(Fig 1.)** The reaction then leads to the emission of light from the Ruthenium which is all caused by adding voltage to the immunological complexes. ==== ====

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This type of luminescent is similar to most forms of luminescents, except that it has advantages others do not. The electrochemical reaction is able to control the time and position of the light being emitted, similar to a catalyst. Furthermore, this type of reaction involves no use of radioisotopes and measurements can be found quickly. ======

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Electrochemiluminescence can be found in many human applications such as devices detecting disease, infections and pregnancy. They are even used to DNA-probe assays to branch out RNA and DNA molecules in nucleotides. One main focus however, is the application on DNA sensors. A recent journal section suggests and states that students in Nanjing University in China have discovered and tested a DNA detecting unit innovated through the use of electrogenerated chemiluminescence. They use gold nanoparticles with a DNA hairpin, within close range of the CdS:Mn (in solution) which then results in longer strands of DNA. Since the DNA grows to greater segments the gold nanoparticles amplify the electrogenerated chemiluminescence. The sensor is sensitive to long, distance, nanoparticles so because of that, a stronger process occurs. **(Fig. 2.)** ======
 * Fig. 2. //The electrochemical process of the DNA detecting system.// **

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Overall, electrochemiluminescence provides a safe and very useful way to emit light through electrodes. It’s used in many places in society and has become a great benefit to the overwhelming scientific community.======
 * __ Effects of Chemiluminescence __**

Of all the reactions and energy chemiluminescence produces, some may argue the fact that they cause more harm then good. Rather then just emmitting a colourful light, toxins can arise and cause many health risks. To expand this point, many products such as glow sticks or luminol solutions have the potential to contain serious health risks. The next few sentences will cover some important information on the safety and dangerous effects that some solutions posses. Overall, the chemical reactions that occur may prove to show some positive and negative effects.

Firstly, an example of a product that can prove to aquire health risks would be luminol aqueous solution. Some pros that this substance has include DNA fingerprinting for blood, which basically means it is used to reveal blood marks left around for a forensic team to investigate that may be found through the fluorescent light of luminol. Although luminol is used for practical scenarios, it has its side effects and many other hazards.

Since some chemicals are used to show luminols existent in the dark, it can prove to have harmful and dangerous results based on the "material safety data sheet" for solutions. For one, luminol's basic route of exposure states that it should not be ingested, breathed in, avoid eye contact and avoid hand contact. Some more information suggests that luminol is flammable and very toxic based on the HMIS rating for health and flammability. However, not only does the solution contain risks, but so do the potential chemical reactions of luminol and its disposure.

During the process of combustion, the luminol substance may encounter an incomplete combustion, which can result in toxic fumes like Carbon Monoxide, Nitrous Oxide and Sulfur Dioxide. Going back, if the luminol is not disposed of properly, it can cause environmental effects that organizations take seriously. For example, the U.S. Dot Appendix states that luminol can have an affect on marine and aquatic zones which can have long term adverse affects. Although this may seem that the prodcut appears to be very dangerous, it is only a caution and warning of what effects can be created due to careless and non-informed mistakes. All of this information can be found and read over carefully to truly understand what kind of effects chemiluminescene materials and solutions have on our health and the environment.

__**References:**__ [] [][][] Derek Bains = **__History of Chemiluminescence:__** =

Chemiluminescence was discovered by accident. It was discovered in 1669, by an alchemist named Henning Brand. He was trying to get gold out of human urine, to do this he tried using extreme heat. Obviously this did not work, but by accident he created phosphorus, it was one of the products of the reaction. The phosphorus glowed green when it was in air. There was no heat at all involved when it glowed, but light was still emitted. This was when chemiluminescence was discovered, but it was not called this right away, at first it was called cold light. The term chemiluminescence was created 200 years after the discovery.



Eilhard Wiedermann is credited with the term chemiluminescence. This theory was very hard to explain, especially since he made this term in 1888, where it was very hard to prove that chemiluminescence was possible. Everyone believed that in order for light to be emitted heat must be present. The term luminescence means light emission that is more intense than would be expected from the source’s temperature. The chemi at the beginning was chosen since two chemicals react to create the light. Together they perfectly describe two chemicals reacting without using heat to produce light.

= **__ Major Applications: __** =

Chemiluminescence has many important uses to use, especially since everywhere is trying to pollute less and save the environment. Almost all industrial companies produce pollution, they must have a gas analyzer to see how much nitric oxide they produce and emit. Gas analyzers use chemiluminescence in order to see the amount of nitric oxide in an air sample. The NO (nitric oxide) in the air will react with ozone (O3). When the reaction occurs the NO is oxided to NO2 (Nitrogen Dioxide), which is in an excited state. A small amount of the molecules in an excited state give off photons of light, which releases some of their energy causing them to return to a ground state. The amount of light emitted is measured, and they use it to determine the concentration of NO in the sample.

Chemiluminescence can also help our legal system, because it can make blood glow, where it would normally be impossible to see. It is very useful for police officers, or investigators of a crime scene to help find evidence. They make the blood glow by mixing a luminol powder (C8H7O3N3) with a liquid, which contains hydrogen peroxide (H2O2) and a hydroxide (OH). When they have created this solution they pour it into a spray bottle, but there is only one problem. The main two reactants are the hydrogen peroxide and hydroxide, but there is also one more necessary element. In order to produce a strong enough glow for them to see, and to make it last longer, they need a metal to catalyze the reaction. The solution is checking for the presence of iron to catalyze the reaction. Iron is present in hemoglobin, which is present in human blood. When there is a strong enough glow, the iron has catalyzed the reaction, which means blood is present. This is an oxidation reaction; the luminol is the reducing agent, and the hydrogen peroxide and hydroxide are the oxidizing agents. In the reaction the luminol loses nitrogen and hydrogen atoms, but it gains oxygen atoms, this creates a compound called 3-aminophthalate. The 3-aminophthalate is in an energized state, which means the oxygen atoms move to higher orbitals. They quickly return to a ground state, by emitting the extra energy as photons of light. The emission of light lasts about 30 seconds.

=__Incandescent and Luinescence:__=

In this section, instead of talking just about chemiluminescence, the broader family of luminescence that chemiluminescence belongs to will be discussed. Most will be real world situations, and pouring two liquids to achieve light is not effective for homes. Luminescence is the creation of visible light, without using any heat. The main way luminescence is achieved is through chemical reactions, but it can also be achieved by electrical energy, subatomic motions, and stress on a crystal. In all of these ways an electron becomes excited, when it returns from a higher orbital to its ground state it releases the energy as light. Incandescence is the creation of visible light, through the use of heat. An example of this type of light is a candle stick; this type of light is created when an object is hot enough to glow. When electrons in an atom are heated they move around faster, causing more colisions between them. These collisions transfer energy so that some electrons are in an excited state, this energy is released as light that varies on intensity depending on the amount of energy released.



<span style="display: block; font-family: 'Times New Roman'; font-size: 110%; margin: 0cm 0cm 0pt; text-align: center;"> An incandescent light bulb works by running electricity through a thin filament. The thin filament offers resistance to the electricity, and it turns it into heat energy. The filament then glows because of the heat produced. A fluorescent light bulb uses luminescence to create light. There are electrodes at opposite ends of a fluorescent tube. A mercury vapour is added inside the tube. Electrodes flow from the electrodes on opposite ends, and in the process they bump into mercury atoms. The mercury atoms become excited, and they give off ultraviolet photons to release this energy. There is a phosphor coating on coating on the inside of the tube. The phosphor coating turns the ultraviolet photons into visible light.

<span style="display: block; font-family: 'Times New Roman'; font-size: 110%; margin: 0cm 0cm 0pt; text-align: center;"> Incandescent lighting is used much more than luminescence lighting. This is because incandescent lights are very cheap to make, and cheap initial cost for people. They are also more popular and used in more houses, which means in stores they are easier to find and readily available. But, the biggest problem from them is that they are only 15 lumens per watt effective. A lumen is the unit for the amount of light, a volume of space illuminated by a light source. Luckily, Many people are trying to switch from incandescent to luminescence lights for many reasons. Luminescence is a more efficient way of producing light, because with incandescence most of the energy is converted to heat instead of light. With luminescence all of the energy is converted to light, none is emitted as heat. This makes luminescence much more efficient in creating light than incandescent. Even thought the initial cost is higher for these lights it uses less electricity than incandescent lights, so over a period of time it will be better economically for you. Also, fluorescent lights last sec times as long as incandescent lights. Although we use incandescent light bulbs more, many people are switching to fluorescent light bulbs since they save you money over time, last long, and are more efficient than incandescent light bulbs.

<span style="display: block; font-family: 'Times New Roman'; font-size: 110%; margin: 0cm 0cm 0pt; text-align: center;">On of the big problems with luminescence is that the chemicals used with them are very toxic for the environment, like the mercury in fluorescent light bulbs. But, with the inefficiency of incandescent light bulbs, where most of the energy is heat, a new technologies need to arise to lessen the risk and effects of these toxins so luminescent light can be more applicable in society today. = __** References: **__ = http://chemistry.about.com/b/2010/08/07/luminol-chemiluminescence-test-for-blood-demonstration.htm http://www.k2bw.com/chemiluminescence.htm [] [] [] [] [] [] [] [] []