Everyday Applications drilling and cutting alignment and guidance reading bar codes recording and playing compact discs. Chemistry Concepts in Lasers

Size: px

Start display at page:

Download "Everyday Applications drilling and cutting alignment and guidance reading bar codes recording and playing compact discs. Chemistry Concepts in Lasers"

Brittany Griffith
6 years ago
Views:

The Chemistry of Lasers How is Chemistry Related to LAser technology?

emission of photons from excited atoms or molecules. LASER is an acronym for L ight A mplification by S timulated E mission of R adiation ".

Lasers Electromagnetic radiation A type of radiant energy, carrying energy throughout space, that travels in waves.

Electronic Structure The number, energy, and arrangement of electrons in an atom.

1 The Chemistry of Lasers How is Chemistry Related to LAser technology? Definition of Laser A device that generates an intense beam of (nearly monochromatic, single wavelength) electromagnetic radiation by stimulated emission of photons from excited atoms or molecules. LASER is an acronym for L ight A mplification by S timulated E mission of R adiation ". Everyday Applications drilling and cutting alignment and guidance reading bar codes recording and playing compact discs Chemistry Concepts in Lasers Electromagnetic radiation A type of radiant energy, carrying energy throughout space, that travels in waves. There are seven types of electromagnetic radiation, lasers having to do with the visible spectrum. Electronic Structure The number, energy, and arrangement of electrons in an atom. This helps us understand how lasers carry photons (little energy packets), and can cause electrons to be emitted from metals. Thermochemistry The area of chemistry regarding changes of heat and energy. Teaches us how the movement and speed of molecules relates to the heat energy of a substance. Will help when looking at laser's ability to cool and heat to extreme temperatures.

Electromagnetic Radiation In Lasers Electromagnetic radiation is probably the chemistry concept most directly related to lasers in that Lasers, as a form of light, are by definition an

When talking about lasers we narrow the range of the electromagnetic spectrum to visible light, a wavelength of 390 nm to 700 nm, or a frequency of 430 740 hz.

The wavelength, energy, and frequency of the lasers are related by the given equations. The smaller the wavelength and larger the frequency the closer to purple a laser will get.

2 Electromagnetic Radiation In Lasers Electromagnetic radiation is probably the chemistry concept most directly related to lasers in that Lasers, as a form of light, are by definition an example of electromagnetic radiation. Some of the properties brought by Electromagnetic Radiation are wavelength, frequency, and energy. When talking about lasers we narrow the range of the electromagnetic spectrum to visible light, a wavelength of 390 nm to 700 nm, or a frequency of hz. A change in the wavelength or frequency of the light produced by the laser will change the energy and color. The wavelength, energy, and frequency of the lasers are related by the given equations. The smaller the wavelength and larger the frequency the closer to purple a laser will get. The larger the wavelength and smaller the frequency the closer to red a laser will be. The closer to purple a laser is the greater the energy, the closer to red the less the energy. The main characteristic that separates lasers from natural light sources or light bulbs is that they are Monochromatic, meaning they only have one distinct wavelength.

Electronic Structure In Lasers Since the electronic structure of atoms regards the amount, energy, and organization of electrons in an atom it explains how lasers work.

Once the atoms have gained electrons they will reflect off of a full mirror and a partial mirror until the anion has enough energy to break through the partial mirror into the beam.

3 Electronic Structure In Lasers Since the electronic structure of atoms regards the amount, energy, and organization of electrons in an atom it explains how lasers work. An electric current is run through a medium, usually different crystals or transition metals, to excite the atoms. Once the atoms have gained electrons they will reflect off of a full mirror and a partial mirror until the anion has enough energy to break through the partial mirror into the beam. Once the charged atoms leave the mechanism they fall back to their ground state and release photons. These photons all travel in the same wavelength and create the laser beam. Different mediums will create different energies and wavelengths of photons creating different colored beams. Lasers Use in Photoelectric Effect The photoelectric effect is an example of how lasers can affect other materials electronic structure. Radiant energy, commonly in the form of lasers, can be shot at metals, where the photons in the laser hit into the metal and eject electrons. As a result the laser creates cations in the metal, changing its electronic structure. Different metal have different minimum frequencies to achieve electron ejection.

Thermochemistry In lasers One of the most interesting aspects of Lasers is their duality in purpose in thermochemistry.

Scientists have used lasers to achieve both temperatures at millionths of a degree above absolute zero and at millions of degrees.

First the lasers use X ray electromagnetic radiation which contains more energy than waves in the visible spectrum.

4 Thermochemistry In lasers One of the most interesting aspects of Lasers is their duality in purpose in thermochemistry. Lasers are used in the science lab to achieve both the coldest and warmest temperatures ever recorded. Scientists have used lasers to achieve both temperatures at millionths of a degree above absolute zero and at millions of degrees. Heating We have learned that in order to heat up substances the molecules have to be sped up as much as possible. First the lasers use X ray electromagnetic radiation which contains more energy than waves in the visible spectrum. In addition these lasers are then focused so that all the energy is transferred to a smaller area. So, having a lot of energy focused on one small area creates significant motion in the molecules and a temperature in the millions of degrees. Uses of The Heating Process of Lasers Nuclear Fusion when two atoms are collided at high speeds they combine releasing significant amounts of energy. With laser heating these speeds can be reached outside of stars in outer space. Laser Cutting and Engraving With such focused lasers with so much energy we now have the technology to cut or engrave a variety of materials with a lot of precision allowing for significant detail in the creation of products. Laser Eye Surgery The same precision and energy can be used for medical purposes to reshape the corneas of people without significant risk or pain.

Cooling Everybody associates lasers with heat so I think is it more interesting and surprising that lasers were a huge role in obtaining the coldest temperature ever.

Race to Absolute Zero I suggest watching most of the video sometime because it it very interesting, but the video specifically addresses lasers from 27:35 to 33:00 and 44:50 to 49:50 When cooling a

Scientists found that if they used heavier alkali metals they could surround a cluster of only a few hundred molecules with lasers set at a certain frequency.

5 Cooling Everybody associates lasers with heat so I think is it more interesting and surprising that lasers were a huge role in obtaining the coldest temperature ever. This video shows how scientists have been trying to reach absolute zero for decades, and how lasers were the solution. Race to Absolute Zero I suggest watching most of the video sometime because it it very interesting, but the video specifically addresses lasers from 27:35 to 33:00 and 44:50 to 49:50 When cooling a material the molecules have to be slown down; absolute zero is the point where the molecules are not moving at all. Scientists found that if they used heavier alkali metals they could surround a cluster of only a few hundred molecules with lasers set at a certain frequency. Once that frequency matches the movement of the molecules they can bombard the more massive elements with photons and waves from every direction. This bombardment prevents the molecules from moving any significant distance, creating a temperature of millionths of a Kelvin above absolute zero. Uses for Laser Cooling Both of these are explained in the second portion of the video Creating a Bose Einstein Condensate Quantum computers

6 Conclusion The electromagnetic radiation and electronic structure that we learned about shows how lasers work. The electronic structure shows how the mechanism of a laser uses electricity to charge atoms reflect them into a beam where photons are released and light is created. That is when electronic structure morphs to electromagnetic radiation. Once the beam is released into waves the laser takes the characteristics of electromagnetic radiation, having a wavelength, frequency and energy. Once scientists found out how lasers work they were able to do interesting and useful things with the information, which is where thermodynamics comes in. They were able to use a combination of all three chemistry principles to create something that can both cause the coldest and warmest temperatures ever seen. This allows for many different practical uses for lasers which all originated from knowledge of these chemistry principles.

7 Bibliography Hill, James C., and Theodore L. Brown. Student's Guide: Chemistry: The Central Science, Ninth Edition, Brown, LeMay, Bursten. Upper Saddle River, NJ: Prentice Hall, Print. "How Lasers Work." How Lasers Work. Lawrence Livermore National Loratory, n.d. Web. 23 May Xjng. "NOVA THE RACE FOR ABSOLUTE ZERO Discovery Science Life (full Documentary)." YouTube. YouTube, 18 Feb Web. 23 May "Laser." Wikipedia. Wikimedia Foundation, n.d. Web. 23 May "Race to Absolute Zero." Nova. PBS, n.d. Web. 23 May 2016.

The Basics of Light. Sunrise from the Space Shuttle, STS-47 mission. The Basics of Light

The Basics of Light. Sunrise from the Space Shuttle, STS-47 mission. The Basics of Light The Basics of Light The sun as it appears in X-ray light (left) and extreme ultraviolet light (right). Light as energy Light is remarkable. It is something we take for granted every day, but it's not something