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Spectroscopy

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A Spectroscope is a scientific instrument used to compare the spectra of materials in order to determine what chemical elements compose the material. It is especially used in the fields of Physics, Astronomy, and Chemistry. The spectroscope was helpful in the discovery of helium because the new element was first identified in the absorption lines in the sun and later identified here on earth. Interestingly, not all of the sun's spectroscopic lines are correctly identified even today, some are still mysteries and presumed to be unknown lines of rare elements[1]

History

Isaac Newton, using prisms, described the colorful rainbow like figure that appears in sunlight and named the figure the spectrum. In 1666, Newton mentioned that the colors were always in the same order and could be recombined to make white light. [2]

A Scottish physicist, Thomas Melvill first mentioned seeing the bright, yellow sodium colour when substances were added to alcohol lamp flames viewed through a prism. "Having placed a paste-board with a circular hole in it between my eye and the flame of the spirits, in order to diminish and circumscribe my object, I examined the constitution of these different lights with a prism, (holding the refracting angle upwards) and found, that, in the first case, (No. 25) when sal ammon., alum or potash fell into the spirits, all sorts of rays were emitted, but not in equal quantities; the yellow being vastly more copious than all the others put together, and red more faint than the green and blue."[3]

Emission Spectroscopy

Hot atoms can give off light that is characteristic for each different element that is heated. This light can be categorized by the colors given off, and often the light is so specific in frequency that it forms a series of lines in certain colors. Since the atoms are emitting light, spectroscopy that depends on the light is called emission spectroscopy.

Absorption Spectroscopy

Infrared Spectroscopy

Infrared spectroscopy is a commonly used spectroscopic method used by organic and inorganic chemists. Infrared (IR) spectra is infrared radiation data collected within a special instrument called an IR spectrometer and is used in an attempt to absorb frequencies by placing gases, liquids or solids in the way of the IR beam. This in turn allows information about the structure of a compound to be known, then analysis can be done regarding purity. When the appropriate data is collected minimal information in favorable conditions is gleaned within a 1% margin of error. [4]

X-ray Spectroscopy

Main Article: X-ray spectroscopy

X-ray spectroscopy is a technique that is used to find the action of inner electrons of atoms. X-rays can be connected in many ways when it strikes an object. They can be diffused or cause light, and they can be photoelectrically engaged. Medical X-rays, security screening and scattered X-rays are the basis for absorption. These are used to figure crystal structure. when the object is exposed to the primary sources the fluorescence becomes the secondary x-rays. Fluorescence becomes the formation of the secondary X-rays. The elements in the object and the intensity of each depends on the concentration, the wavelength of these secondary X-rays matters. Analytical XRF could be the main basis for these. [5]

References

  1. New and Alternative Line Identifications in Solar Chromospheric and Photospheric Spectra by S. O. Kastner, Astrophysical Journal Supplement v.100, p.473, Oct. 1995, Accessed Abstract 27 June 2010.
  2. History of Spectroscopy: 300-1800, The Spectroscopy Net, Accessed 28 June 2010
  3. Observations on Light and Colours by Thomas Melvill, The Digital Library for Physics and Astronomy, Site hosted by the High Energy Astrophysics Division at the Harvard-Smithsonian Center for Astrophysics, the paper, originally read January 3 and February 7, 1752, was reprinted in the Journal of the Royal Astronomical Society of Canada, Vol 8. pp 242-243, July-August, 1914. Accessed 29 June 2010.
  4. Infrared Spectroscopy by C.-P. Sherman Hsu, Ph.D.
  5. xray spectroscopy smu. Web. May 28 2013 Accessed, Author unknown.

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