Lasers:

Definition of a Laser:

The laser is a device that produces a nearly parallel, nearly monochromatic, and coherent beam of light by exciting atoms to a higher energy level and causing the energy to be released in a specific way. It is an acronym for "Light Amplification for Stimulated Emission Radiation" or "light radiation" and a laser has many different uses, from commercial to scientific to entertain. The laser light amplifier can become a laser oscillator, a different light source. The term “laser” isn’t truly accurate, for “laser” often refers to an oscillator, and the term “amplifier” should be used when the laser in question is not an oscillator. Laser devices are powerful enough to cut through metal, exact enough make intricate, detailed designs, and strong enough to give the quality of heat necessary in many scientific experiments. The laser is a fantastic invention who’s many varied uses makes it widespread device that many depend upon in today’s world.

Lasers acronym means LightAmplification
laser.jpg
Demonstration
Stimulated by the Emission of Radiation.

Introduction:

Maser
Maser
The laser began with the invention of the maser (microwave amplification by stimulated emission of radiation) by Charles
to produce coherent electromagnetic waves. The maser was first used to amplify signals for space research, and it is currently used in high frequency precision devices, such as atomic clocks, electronic amplifiers, radio telescopes. Masers are also being developed as directed-energy weapons.
There are several types of lasers that developed from the maser. These include the ruby, the Gordon Gould, gas, Semiconductor Injection, and Carbon Dioxide lasers. All of these lasers are optical lasers, which was an innovation pioneered by Gordon Gould. Since their invention, lasers have been incorporated into many modern day devices, ranging from computers to laser eye surgery.

You can find lasers in many different devices from CD players to dental drills to high-speed metal cutting mac­hines to measuring systems. Also, tattoo removal, hair replacement, and eye surgery use lasers. Lasers can be used to cut precise patterns in glass and metal, to reshape corneas to correct poor vision, and to provide intense heat in controlled fusion experiments. We also use lasers as very precise light sources in supermarket checkout lines, CD players, and to transmit most telephone signals.

Lasers are astonishing light beams powerful enough to zip up miles into the sky or sever metal. Once the stuff of science fiction, they have proved themselves to be among the most multipurpose inventions of modern times. The miniaturized laser beam that reads music in a CD player can also guide missiles, send emails down fiber-optic telephone lines, and barcode scan goods at the supermarket checkout.The basic idea of a laser is simple. It's a tube that concentrates light over and over again until it emerges in a really powerful beam. But how does this happen, exactly? What's going on inside?

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History of Lasers:

The Beginning:

photophone.jpg
Photophone

The principle of the laser was first known in 1917, when physicist Albert Einstein described the theory of stimulated emission. However, it was not until the 1940s that engineers began to make use of this principle for practical purposes. At the start of the 1950’s different engineers started working towards the harnessing of energy using the principal of stimulated emission.The development of the laser began with the photophone which was invented by Graham Bell. This laser consisted of a thin mirror, a receiver that could detect light, wires, and an earpiece. The person who spoke near the mirror would cause the sunlight to vibrate into the earpiece. The receiver then changed the light vibrations into an electrical signal that traveled through the wires to the earpiece. However, the photophone was faulty in that sunlight is not reliable and varies during the day. The photophone was the first step towards the development of the laser.

Microwaves:

Scientists had the basic information to build a laser as early as 1917 but no one attempted to make a laser until much later. In WWII, scientists improved radar and microwaves. Radar sends out beams of microwaves to bounce off objects. Microwaves are similar to visible light but are invisible to the human eye. These two developments were basic ideas in the making of the laser. In 1951, a scientist by the name of CharlesTownes realized that it was possible to use molecules of ammonia to produce a powerful microwave beam. If the ammonia molecules were kept in a state of excitement for a long period of time, it could create more microwaves. Waves would then become more concentrated and powerful causing them to become amplified.

The Maser:

FirstMASER.jpeg
MASER
The Microwave Amplification by Stimulated Emissions of Radiation (MASER) developed in 1954. In this laser, ammonia gas was heated until molecules that were excited were separated from unexcited molecules. These excited molecules would then flow into the resonator where stimulation took place. The ammonia molecules emitted microwave particles that would bounce back and forth inside the chamber. Whenever these particles got near an excited ammonia molecule, they would give off their own particles causing the production of more

particles. This process only lasted a fraction of a second. However, the MASER only had a few practical uses. It could keep reliable time because the molecules vibrated at a stead rate, and it could work as an amplifier boosting weak microwave signals given by distant stars.

I
Ruby-Laser.gif
Ruby Laser Diagram
n 1957, Townes drew a design for an optical maser. Two months later, Gould developed a device he called a “laser. It was the same design as Townes optical maser but Gould could not get a patent. Townes then stole the name “laser” and got a patent. On July 7 1960, the first successful device appeared. This small and complicated device was built by Theodore H. Maiman. The core of the laser was an artificial ruby and was called the “ruby laser.” The ruby acted as a medium that supplied atoms to be stimulated. The laser used a flash lamp to run through a glass tube that was bent into the shape of a coil and wound around the ruby. The flash lamp caused excited atoms to give off photons. These photons were then reflected off the mirrors and, in turn, excited more and more ruby atoms which then created more photons. The creation of more photons amplified the light in the ruby. In order to create a laser, a partial mirror was put on part of the ruby that allowed some photons to escape. These escaped photons became the actual laser beam. This whole process only took a few millionths of a second. The ruby laser was the start of a craze for lasers. Because several researches came up with the same idea around the same time, it is difficult to figure out who the actual inventor was. Basically, Townes and Schawlow received patents for the basic laser principle, while Maiman received a patent for the ruby laser.

Scientists realized that they could also use other materials in the making of lasers. The first gas laser used helium, neon, and other substances such as crystals, carbon dioxide, vaporized metal, and colored dyes. As different types of lasers developed, they were used for more things. Astronomers used the lasers to study stars and the sun. Engineers wanted to use lasers to cut and weld metal parts, while doctors wanted to use lasers in eye operations and for removing tumors. Military wanted to use the laser to create death rays.


The laser further developed to suit these needs. In 1962, the US air force investigates the use of lasers against intercontinental ballistic missiles. In 1977 the USAF develops a high-power Chemical Oxygen Iodine Laser (COIL). The USAF also uses a gas laser to destroy five small anti-aircraft test missiles. In 1985 an SDI laser destroys a Titan rocket at launch in tests. The SDI is abandoned in favor of Airborne laser (ABL) because of cost. The military as well as other fields have found great uses for the invention of the laser.

Important Researchers:

Gordon Gould:

g.g..jpg

Gordon Gould was born in 1920. He attended Columbia University where he was working for a PHD in physics. He was inspired to make a laser by Towne’s invention, the microwave in 1958. He began to study light waves along with the microwave concept. He designed a device, a light laser, that he thought could heat a substance to the temperature of the sun and a millionth of a second. He sketched drawing of how the apparatus would emit powerful light. He spent his time in 1958 refining and perfecting his laser he made an appropriate optical resonator by using two mirrors in the form of a Fabry-Pérot interferometer. Gould considered pumping of the medium by atomic-level collisions, and anticipated many of theuses of such a device. It did not file for a patent until 1959. Theodore Maiman tried to take credit for the laser, and Gould took him to court. It was in 1973 that Gould won. It took Gould twenty years before his laser patents were officially issued.


Dr. Ali Javan:

ali.jpegDr. Ali Javan was born December 26, 1926, in India. In 1 948, he immigrated to the United States. There, he attended Columbia University, and got his Ph.D in physics. When Javan was researching in Bells Lab after graduation, he came up with the idea of a gas laser composed of helium and neon, which he ended up co-inventing. The gas laser was a continuous-light laser and the first laser to operate "on the principle of converting electrical energy to a laser light output." Javan received his U.S. patent for it in 1960. On December 12, 1960, he tested his invention for the first time. The gas laser laid the foundation for the fiber optic communication today. It is considered the most useful, profitable, and practical type of laser in use. Today’s uses for the gas laser include: holography, UPC code checkout scanners, and other construction, medical, and monitoring technology.



goldman.jpgLeon Goldman:

Leon Goldman received his medical degree at the University of Cincinnati in 1929, and in 1945 he was appointed the director of dermatology there. In 1961, Dr. Goldman became the first

researcher to use a laser to treat a human skin disease, melanoma. This method later became very popular in removing birthmarks and tattoos without much scarring. For the majority of his career, Goldman continued teaching at the University of Cincinnati. In 1969, he supervised the first laser operation in which a laser was used to remove a tumor without causing bleeding. In 1979, Leon Goldman help find the American Society for Laser Medicine and Surgery, and two years later became the first president. Also in 1979, Leon Goldman was officially designated the father of Laser Medicine. He then went on to write 6 books about laser medicine and over 100 articles for medical journals. Dr. Goldman died in December of 1997.

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Types of Lasers and How They Work:

Atoms, Electrons, and Light

Overview of an Atom:

An atom is composed of a nucleus and surrounding, orbiting electrons held in place by powerful magnetic changes. Atoms store energy by moving faster or slower than usual. These levels are called “states of excitement.” If more energy is added, an atom can go from a “Ground State” level of energy to an excited level. Energy can be added to an atom by heat, light, or electricity.

Electrons and Photons:

When light or another energy source hits an atom, the energy is absorbed by the electron and bumps the electron up to a higher energy level. Later, it gives off the same light and energy in a random direction. The particle of light and energy that the electron gives off is called a photon.

Light and Lasers:

A laser beam is essentially focused light. However, laser light is a very different kind of light than normal light. Laser light is set apart because it is monochromatic, coherent, and collimated light.
Monochromatic: Light that is only one color throughout. White light is light made up of all the colors. Laser light, however, is a single color.
Coherent: Coherent describes light that is moving on the same wavelength. All the wave crests and troughs (high and low points) are lined up along the beam.
Collimated: Collimated light is light waves that are traveling in the same direction, parallel to one another.

Parts of a Laser:

Lasing Medium

Energy Pumper

Resonator


Gas Lasers

Gas lasers run an electrical charge through a gas to create light. Gas lasers are broken into three different types of lasers: Neutral Gas lasers, Ion lasers, and Molecular Gas lasers. They are classified according to the transitions their contents go through to create light. HE-NE_Laser_schematics.pngThese can be atomic or molecular changes. The Helium-Neon laser was the fist gas laser invented by Ali Javan and William r. Bennett in 1960. These lasers are very common because the materials they use are all very abundant and cheap. They mostly create red light, but can create green, yellow, UV, and IR rays as well. They have a cathode on one end and an anode on the other where the electricity is run through. A tube called the ballast controls the amount of gas. As in all lasers, they have a mirror on each end. The photons, He-Ne_Laser.pngor particles of light, reflect off of the mirrors and move back and forth through the gas. This excites the electrons and creates more photos of the same wavelength. Some of the light is let through the mirror on the front called the output coupler, which creates a laser. This laser is classified as a neutral atom laser because this happens between two types of atoms that are very stable and without charge. Ion lasers also occur on the atomic level, but result in ions, which have a charge. These lasers are more powerful than neutral atom gas lasers and can create many different wavelengths. Sometimes scientists even combine two gases to create an argon-krypton laser. Molecular gas lasers are lasers that use a gas formed of molecules, Wavelengths.pngor atoms that are bonded together. A carbon dioxide laser also releases energy with light so it can cut or weld things together. Excimer lasers are a very specific type of molecular gas lasers. They use inert gases (argon, krypton, or xenon) that do not want to react and halide gases (chlorine, fluorine, bromine), which are very reactive together. A strong electrical charge forces the two different gases to bind together for a brief period of time in an excited state, creating a laser, and then break apart. These lasers are not very popular because the reactive halide gases make them dangerous.

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List of common gas lasers:

Neutral Atom Gas Lasers
-Helium-Neon Lasers (most common laser)
Ion Lasers
-Argon Ion Lasers
-Krypton Lasers
-(Experimental: Oxygen, Xenon, and Iodine)
Molecular Gas Lasers
-Carbon Dioxide Lasers
-Carbon Monoxide Lasers
-Nitrogen Lasers
-Excimer Lasers- uses Argon, Krypton, or Xenon mixed with Fluorine, Chlorine, or Bromine

Solid-State Lasers

Solid-State Lasers are based on solid-state gain media that involves crystals and glasses doped with transition metal ions or semiconductor lasers. They are the first lasers to be created. They use a ruby rod (chromium doped aluminum oxide) that is surrounded by a helical xenon flash lamp that pushes it toward the two mirrors on each end with one mirror being transparent. The energy that the solid state lasers and other lasers give off is a monochromatic, coherent, and collimated force of energy. They can generate output powers of a few milliwatts and many kilowatts. Solid State lasers have Q switching which is technique for getting short pulses of energy from a laser by beating the intraca
end_pumped_laser.png
End-pumped bulk laser
vity of the laser making Q factor of the laser resonator.

The different types of
side_pumped_laser.png
Side-pumped bulk laser
solid-state lasers include ion-doped solid-state lasers that are bulk lasers, fiber lasers, and waveguide lasers, and diode-pumped solid-state lasers. The bulk lasers (to the right and left) convert and pump the light (blue) into a raser light (red). Diode-pumped solid-state lasers have compact setup, last a long time, and have great beam quality.



Chemical Laserswan_t_pic.jpg

Chemical Lasers are lasers that obtain their energy through a chemical reaction; like all other lasers, their energy is released in the form of a focused beam of light energy that is monochromatic, coherent, and collimated. They are used to cut things. Their continuous waves reach a megawatt of power. Megawatts are a good quality beam. Their beams are in the middle of the infared region, which means their wavelengths are between 10-6 to 10-4 meters long. This information can be acquired on the electromagnetic spectrum. Some examples of these lasers are chemical oxygen iodine laser (COIL), all gas-phase io dine laser (AGIL), the hydrogen fluoride laser, and the deuterium fluoride laser.

Chemical Oxygen Iodine Laser (COIL)coil_thing.gif

The COIL like all other chemical lasers produces an infrared beam. Humans cannot see this beam because of this. The COIL works by being given chlorine in its gas form, iodine, hydrogen peroxide in its liquid form, and potassium hydroxide in its liquid form as well. They all react and produce heat, potassium chloride, and oxygen in its “excited” state. After this, the iodine produces the light that can cut things.

All Gas-Phase Iodine Laser (AGIL)


The AGIL is made to get rid of the problems the COIL has, but accomplishes the same task. The AGIL uses chlorine, gas hydrazoic acid, and an “excited” form of nitrogen chloride. After these chemicals react, the iodine produces the light.

Deuterium Fluoride Lasers
Deuterium_Fluoride_Lasers.jpg
The Deuterium Fluoride Laser can be used during war.

Deuterium Fluoride Lasers are a form of chemical laser that produce light through a reaction of different gasses. These gasses are Deuterium and Fluoride. When they react, a beam is released that is designed to cut materials. These lasers are an improvement of the Hydrogen Fluoride Lasers.



Hydrogen_Fluoride_Laser_pic.gif

Hydrogen Fluoride Laser

The Hydrogen Fluoride Lasers come in two types, depending on whether or not they contain hydrogen or deuterium. The ethylene, nitrogen trifluoride, and hydrogen (or Deuterium) all react and they produce light. When hydrogen is used, the signal is absorbed in the atmosphere. However, deuterium can go into space and are a different type of laser.

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Uses of lasers:


Entertainment:

Lasers have grown in popularity in recent years in the entertainment industry. Lasers involved in the entertainment industry provide incredible special effects with thousands of color options, awing audiences everywhere. The effects in laser light shows consist of two major categories: beam effects ad screen effects.


Beam effects occur when the lasers move through the air over the audience, where they are seen. There are two types of beam effects. Static beam effects are stationary and merely turn on and off and dynamic be am effects utilize lasers that move on an X and Y axis.
Screen effects during laser light shows include when lasers are projected onto a stationary surface such as mountains, walls, and buildings. These laser shows can include graphics, animation cycles, and other optical effects.


Medical:lasik_surgery.jpg

Lasers are used in most basic ally every industry, medicine, computers, entertainment, and construction. Medical lasers are used for many operations and surgeries. One of the most popular forms of medical lasers is hair removal. The laser is basically a light at a certain wavelength that goes into the skin. It usually focuses on dark material which is usually the pigment in hair. This can cause thermal and medical damage to a hair follicle.

Lasers can also be used for wrinkle treatment. They can reduce many wrinkles in

the skin. Lasers are used in many medical operations. They can remove birthmarks, warts, and discoloring of skin. These operations are not very long and heal quickly. Lasers can also be used to improve eye sight by reshaping the cornea, whiten teeth, and also to reshape the face for plastic surgery.

Many doctors have begun using therapeutic lasers for medical procedures. For example the TerraQuant® developed by Multi Radiance Medical, relieves pain and swelling. These devices are clinically proven to speed healing.

Lasik Eye Surgery:

There are many ways lasers will be helpful in the future. One such use is laser eye surgery. In this lasers are used to repair or correct someone’s eyes who are damaged or correct there nearsightedness or farsightedness. Because the laser beam is so quick and powerful, it can precisely burn through a very small amount of eye tissue. By pointing the laser on the tissue that is damaged,

it can easily be fixed without damaging surrounding tissue that is still good. Without lasers, it would have been almost impossible to reach achieve so many successes and treat many eye problems. Lasers are always advancing to better help society. The lasers of the future will become even more advanced than today’s.


Manufacturing:

Lasers can also be used for cutting. Laser cutting is typically used in industrial manufacture. Laser cutting uses a high power laser aimed at the material to be cut and controlled by a computer. The material is then burned or vaporized, then taken, moved, or blown away from the cut sight for a good clean cutlaser_robot.jpg. Industrial lasers are usua lly used to cut flat sheet metal, but sometimes also for pipe and structural products. Lasers are also used to etch pictures or designs onto materials.

Though energy cutting takes a vast amount of power, it has its advantages over mechanical cutting. There is no physical contact with the material being cut, and since there is a low area of heat concentration, it is less likely that the material will warp. Laser cutting also h as a vast amount of precision to a degree.
There are three types of lasers.CO2 lasers are used for boring, engraving, and cutting. Neodymium and neodymium yttrium-aluminum-garnet lasers have the same design, but have different uses. Both lasers are used for boring and all three can be used for welding.

The geometry of the beam affects the smoothne ss of the cut. Most beams are focused to be about a 0.001 inch dot, which makes the beam very intense and more powerful. During cutting, to achieve a much smoother cut, the direction of the polarization must be rotated as it cuts the material.

There are many different types of cutting in the manufacturing field, such as vaporization cutting, melt and blow cutting, thermal stress cracking, burning stabilized laser gas cutting, and tolerance and surface finish.

CD and DVD Drives:

Lasers are used in CD players, DVD players, game systems, computer disc drives, and just about every piece of technology utilizing CDs or DVDs. When CDs are read in disc drives, a drive motor is used to spin the CD and a laser and lens system concentrates on reading the bumps engraved into the CD.

When a DVD or CD is created a laser is used to burn bumps into the underbelly of CDs.The bumps are interpreted as images and sound by a laser detecting if a bump is or is not present in a particular location on a CD. If a bump is present the computer interprets that bit of information as a 0 and if a bump is not present the piece of informatio n is interpreted as a 1. The 1’s and 0’s are interpreted by the computer as sounds and images.
Recently in the customization of CD’s and DVD’s a new technology called LightScribe has come into use. LightScribe technology uses a laser to burn text and images onto the tops of special CD’s providing a clean and professional looking disc.

Lasers in Computer Mice:

A laser mouse uses a laser to track movement of the users hand instead of a trackball. They are said to have better tracking ability than those of other mouses. The laser enables around 20 times more surface tracking power to the surface features used for navigation compared to conventional optical mice, via interference effects.There are less moving parts on a laser mouse than a mouse with a trackball making it harder to damage.The laser mouse uses an infrared laser diode instead of an LED to illuminate the surface beneath their sensor. The laser helps to significantly increase the resolution of the image taken by the mouse.


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Future Possibilities and Applications:

Future Lasers:

Laser!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.jpgThe United Kingdom launched a new project that will promote the use of lasers with nuclear fusion for a source of energy. It is being funded by the European Commission consisting of the UK, French and Czech governments. The European High Power Laser Energy Research partners or HiPER is formed by 26 conventions from 10 different nations. They are all trying to build Europe’s largest and most extreme laser to produce energy. The Science and Technology Facilities Council or STFC are waiting for American and French scientists to end the 50 year wait for laser-powered nuclear fusion, which they believe they will achieve within the next t wo years. If developed successfully the laser should be able to power an energy plant, but the laser fusion would have residual radioactive waste; however, HiPER emphasized that this waste has a lifespan of around a hundred years which is significantly lower than that of conventional nuclear fission plants, an d emits no carbon by-products.

Research using the lasers could potentially allow scientists to observe nuclear physics and its energy capability in conditions that cannot otherwise be created on this planet. Professor Mike Dunne says "What this scale of laser lets you do is recreate, down here on earth, some of the most extreme conditions found anywhere in the universe. If you could go to the center of the sun, or to the heart of an exploding supernova and study the physics that's going on inside those extreme events, it would be the same as studying them here on earth. You can study cause and effect, and really test our understanding of that kind of science."

Solid-state-heat-capacity-laser:

Science fiction has been predicted by a scientific reality. Last December, that generic bit of sci-fi drama took a step cHiPER_laser_building@body.jpgloser to reality. In a demonstration at the White Sands Missile Range in New Mexico, the solid-state heat-capacity laser (SSHCL) burned a 1-centimeter-diameter hole directly through a 2-centimeter-thick stack of steel samples in 6 seconds. The electrical current came from a wall outlet and cost no more than 30 cents. While large chemical lasers have successfully shot down tactical rockets, the SSHCL design supports the weight and size requirements for a future portable operation.
The SSHCL, designed and developed at Lawrence Livermore National Laboratory in Livermore, California , is the model of a laser strategic weapon, which shows pledge as the first high-energy laser compact enough in size and weigh t to be a well thought-out part of the Army’s future combat system (FCS) for short-range air defense. The FCS is a factor of the Army’s vision of sensors, platforms, and weapons with a networked authority and control system. The more sophisticated version of the laser weapon system, which is now under development, will be battery-powered. It is only 2 meters long and less than a meter across. It is small enough to be mounted on a hybrid-electric high-mobility multipurpose wheeled vehicle (Humvee). In this configuration, the Humvee’s generator and batteries could power both the vehicle and the laser, requiring only diesel fuel to support full operation.

The SSHCL offers speed-of-light precision engagement and annihilation of a variety of targets, including short-range artillery, rockets, and mortars. There is a recent need for effective security against these weapons on the battlefield. The project is sponsored by the U.S. Army Space and Missile Defense Command and has a number of commercial partners, including General Atomics, Raytheon Co., PEI Electronics Inc., Northrop Grumman Corp., Goodrich Corp., Armstrong Laser Technology Inc., and Saft America.


Bluetooth Laser Virtual Keyboard:

Sporting a blood-red, red diode laser as its light source, you’ll get a 11.6″ (295mm) x 3.74″ (95mm) keyboard projection which is perfect for longer typing jobs on your movable devices. With a recognition rate of up to 400 characters per minute, it will keep up with even the fastest typists among us - rapidly transmitting as far as 9 meters from your machine.

ThRed_Laser_Keyboard.gife unit includes virtual key-click sounds for feedback during use and its built-in lithium-ion battery is good for up to 120 minutes of solid typing, so you can use it on the go without needing to be tethered to a wall.The Bluetooth Laser Virtual Keyboard supports most major operating systems including PalmOS 5, PocketPC 2003, Windows Smartphone, Symbian, Windows 2000/XP and will also work on Mac OS X through its native Bluetooth support (albeit without drivers and thus, no settings options).Measuring a mere 1.38″ (35mm) x 3.6″ (91.4mm) x 1″ (25.4mm), the Bluetooth Laser Virtual Keyboard is tirelessly tracking the dozens of digits over at ThinkGeek.


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Whats your favorite color Laser?
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http://www.utilipoint.com/issuealert/print.asp?id=1728
http://en.wikipedia.org/wiki/Potassium_hydroxide
http://en.wikipedia.org/wiki/Heat
http://en.wikipedia.org/wiki/Oxygen
http://en.wikipedia.org/wiki/Chlorine
http://en.wikipedia.org/wiki/Hydrazoic_acid
http://environmentalchemistry.com/yogi/chemicals/cn/Nitrogen%A0chloride.html

http://en.wikipedia.org/wiki/Gas
http://en.wikipedia.org/wiki/Fluoride

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