THE BASICS ABOUT SPECTROSCOPES AND SPECTROSCOPY

 

     Scientists use tools to help them understand the universe, galaxies, stars, and planets.  A major tool used to gather information about these objects is called a spectroscope.  The scientific techniquie that utilizes the spectroscoe is called spectroscopy

 

     Spectroscopy is a technique used to help scientists determine the comosition of objects made up of hot incandescent gases (like stars) and cool gases (like planetary atmospheres).  Spectroscopes or spectrometers are used to analyze the amounts and types of spectral light that comes from these objects.  This is fairly easy to do.  You can build your own spectroscopes to do your own spectral analysis of gases.

     Spectroscopes break down the light emitted or absorbed by chemical elements into specific lines of color.  Every chemical element has a "fingerprint" of its own that can be used to identify it.  These fingerprints are generally produced when electrons change orbital levels as they gain or lose energy.  Different energies produce differnt colored lines.

     Every chemical element on the periodic table has its own spectral fingerprint that identifies it.  When looking at spectra from objects like stars and planetary atmospheres, it is easy to identify the chemical elements present by matching the colored spectral lines with the elements spectral fingerprint.

     There are three basic types of spectra that scientists use in spectroscopy.

CONTINUOUS SPECTRA:  

 
     A continuous spectra is one that shows all of the colors of the rainbow blended next to each other in a band.  Continuous spectra can be produced by glowing materials such as the white hot wires found in incandescent light bulbs.   
 

ABSORPTION SPECTRA:

 
     Absorbtion spectra can be identified by the black bands of missing color present in a continuous spectra.  These black bands are produced when the chemical elements present in a cool gas absorb the incoming energy of a light source behind it.
 

BRIGHT LINE EMISSION SPECTRA: 

 
     Bright line emission spectra can be identified by the bright bands of color present on top of a black background.  These colored bands are produced by the chemical elements present in a hot incandescent gas.  Stars and tubes of heated gas can produce bright line emission spectra.  
 

CONTINUOUS EMISSION SPECTRA: 

 
      Continuous emission spectra can be identified by the bright bands of color present on top of a continuous spectra.  The colored bands are produced by the chemical elements present in a hot incandescent gas.  The continuous spectrum is produced by the merging of those lines.  Such sontinuous emission spectra can be seen when looking at florescent light fixtures.  The white coating on the bulb mixes the elemental lines of the gas inside to produce the continuous spectra while the bright lines come from the gas inside.
See the Lessons and Activites section for deomstration ideas of these types of spectra.

 

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