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SPECTROSCOPY

SPECTROSCOPY. Prepared by: Miss Sasha Dofflemeyer Earth Science Bell-to-Bell Lesson Class of Mr. Stephen Deer Held on October 16, 2009 3 rd Block. Definition. The definition of spectroscopy is the study and analysis of spectra.

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SPECTROSCOPY

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  1. SPECTROSCOPY

  2. Prepared by: Miss Sasha Dofflemeyer Earth Science Bell-to-Bell Lesson Class of Mr. Stephen Deer Held on October 16, 2009 3rd Block

  3. Definition The definition of spectroscopy is the study and analysis of spectra. The formal definition of the word spectrum means a band of the various colors of light.

  4. This spectrum can be visible when white light passes through a glass prism and produces a rainbow of colors: red, orange, yellow, green, blue, and violet.

  5. In spectroscopy, here are a few of the definitions you must know to fully understand the subject matter.

  6. What is light? Light is a disturbance of electric and magnetic fields that travels in the form of a wave. This is called a light wave. What are the parts of this wave?

  7. wavelength - the distance between two wave crests.

  8. frequency - the number of times a specified periodic phenomenon occurs within a specific interval. 1 interval 1 10 15

  9. continuum spectrum

  10. The science of light. In terms of modern usage, spectroscopy is defined as the technique used to capture and analyze the light from an astronomical body. In spectroscopy, a spectroscope is used to separate the light into a series of lines called the spectrum.

  11. Marked scale to read spectra Look through here Slit opening Front View Top View Spectroscope Diffraction grating

  12. emissions spectrum of elements Each element has a unique emissions spectrum. It is emitted by hot dilute gas. The spectrum of any given element depends on the relative intensity of electromagnetic radiation of each frequency emitted by atoms or molecules by that element when they are excited.

  13. absorption spectrum of elements Each element has a unique absorption spectrum. It is an accompaniment to the emissions spectrum. It consists of dark lines superimposed on a continuum spectrum. The spectrum is produced when a continuum spectrum travels through cool, dilute gas.

  14. emission spectrum of hydrogen.

  15. emission spectrum ofiron.

  16. Astronomers use spectroscopy to classify stars. By analyzing the spectrum of astronomical objects, Earth-bound science has been able to determine: • the temperature and chemical makeup of the stars. • star velocities relative to our own. • confirm that the Universe is expanding.

  17. Temperature

  18. Chemical Makeup How can scientists determine a star’s chemical composition from spectroscopy? Did you guess Hydrogen and Magnesium? You are correct! star spectra

  19. Star Velocities λν = v Where: λ (lambda) = wavelength ν (nu) = frequency v (ve) = velocity

  20. Expansion of the Universe A spectrum can tell astronomers what an object is made of, how hot it is, how fast it is moving, and a host of other important attributes. red shift - An increase in the wavelength of radiation emitted by a celestial body as a consequence of the Doppler effect. blue shift - A decrease in the wavelength of radiation emitted by a celestial body as a consequence of the Doppler effect.

  21. Expansion of the Universe • Spectroscopy revealed the expansion of the universe. • When an object moves away from us, the lines in its spectrum get displaced toward longer wavelengths. • The amount of this so-called redshift is proportional to the object’s velocity. • Edwin Hubble first showed that the spectrum of almost every galaxy is shifted to the red. • The farther away the galaxy, the greater the redshift. • From these observations, astronomers correctly concluded that the universe was expanding.

  22. additional examples emission spectra of elements: http://jersey.uoregon.edu/vlab/elements/Elements.html

  23. Works Cited College of William and Mary. Physics Department Physics 177 Introductory Astronomy Laboratory. Holt, Rinehart, and Winston. Modern Earth Science. CNN. 2000: Austin http://jersey.uoregon.edu/vlab/elements/Elements.html accessed on 10/10/2009 http://en.wikipedia.org/wiki/Atomic_emission_spectrum http://education.yahoo.com/reference/dictionary/entry/frequency http://amazing-space.stsci.edu/resources/explorations/light/star-light-science.html http://www.pbs.org/wnet/hawking/strange/html/spectro.html

  24. Questions?

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