spectrochemical analysis

spectrochemical analysis

Any of a group of chemical analysis methods that depend on measurement of the wavelength and intensity of electromagnetic radiation. It is used chiefly to determine the arrangement of atoms and electrons in molecules on the basis of the amounts of energy absorbed during changes in their structure or motion. In more common usage, it usually refers to ultraviolet (UV) and visible emission spectroscopy or to UV, visible, and infrared (IR) absorption spectrophotometry.

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Spectrum analysis also known as Emission Spectrochemical Analysis is the original scientific method of charting and analyzing the chemical properties of matter and gases by looking at the bands in their optical spectrum. The empirical laws of spectrum analysis are commonly known as Kirchhoff's Three Laws of Spectroscopy as follows:


In 1835 Charles Wheatstone showed that the light from metals in an electric arc produced characteristic rays when passed through a prism.

In 1854, credit for the origins of Spectrum Analysis goes to Dr. David Alter, a scientist of Freeport, Pennsylvania, who published the first scientific work that included the spectral radiance properties for twelve metals, titled:

On Certain Physical Properties of Light Produced by the Combustion of Different Metals in an Electric Spark Refracted by a Prism.

Dr. Alter began studying the optical properties of matter ever since finding a piece of melted, prismatic glass in the debris of the great Pittsburgh fire of 1845. By 1855, Alter published another article that expanded his original theory by including six gases, including the first discovery of what came to be named the Balmer lines of hydrogen. The proof that elemental gases have spectra peculiar to themselves was an extremely important scientific advance. Alter's article contains a paragraph where he even visualized the application of spectrum analysis to astronomy, mentioning the study and detection of elements in the combustion of shooting-stars or luminous meteors, and daguerreotyped the dark lines of the solar spectrum. David's spectral discoveries were noted in various scientific publications in France, Germany and Switzerland from 1854 to 1860.

Anders Jonas Ångström a physicist in Sweden, in 1853 had presented similar theories about gases having spectra in his work: Optiska Undersökningar to the [[Royal Swedish Academy of Sciences pointing out that the electric spark yields two superposed spectra. Ångström also postulated that an incandescent gas emits luminous rays of the same refrangibility as those which it can absorb. This statement contains a fundamental principle of spectrum analysis.

In 1860, German physicist Gustav Kirchhoff and chemist Robert Bunsen published their own findings on the spectra of eight metals and identified these metals in natural elements. Kirchoff went on to contribute fundamental research on the nature of spectral absorption. Spectrum analysis was then grouped by Kirchhoff into the three fundamental laws commonly called Kirchoff's Laws, these laws integrated both Alter and Ångström's discoveries of radiance and emission with Kirchhoff's fundamental discoveries of absorption.

Johann Balmer discovered in 1885 that the four visible lines of hydrogen were part of a series which could be expressed in terms of integers. This was followed a few years later by the Rydberg formula describing additional series of lines.

In the early twentieth century, spectrum analysis led to "atomic spectroscopy" and quantum mechanics.

See also



  • Alter, David. On Certain Physical Properties of Light Produced by the Combustion of Different Metals in an Electric Spark Refracted by a Prism. Am. J. Sci. Arts 18 (1854): pages 55-57.
  • Alter, David. On Certain Physical Properties of the Light of the Electric Spark, Within Certain Gases, as Seen Through a Prism. Am. J. Sci. Arts 19 (1855): pages 213-214.
  • Ann. Sci. Phys. Nat. (1856): page 151.
  • Brace, D. B. (Ed. and translator). The Laws of Radiation and Absorption: Memoirs by Prévost, Stewart, Kirchhoff, and Kirchhoff and Bunsen. New York, NY: American Book Company, 1901, pages 100-125.
  • Johnson, Allen, ed.; Garraty, John and James, Edward, Eds. Dictionary of American Biography; Supplement Four. New York, NY: Charles Scribner’s Sons, 1974, page 230.
  • Kirchhoff, G. R.; Bunsen, R. Ann. Phys. (1860): pages 110, 160.
  • Liebig and Kopp, Jahresber. Chem, (1854): page 118; (1855): page 107.
  • L’Institut, Paris (1855): 156.
  • Retcofsky, H. L. Spectrum Analysis Discoverer, Spectroscopy Society of Pittsburgh, PA 80 (2003): 1003

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