Spectrochemical Analysis in Communication Research

The foundation of spectroscopy m a y be traced back to the year 1666 when Sir Isaac Newton discovered that sunlight is composed of the several colors, and that it could be separated into its components by refraction with a prism. Newton failed to note the discontinuous nature of the solar spectrum and it was reserved for Fraunhofer, more than a century later, to investigate the absorption lines and to point out their importance. Fraunhofer noticed that the D line absorption doublet in the solar spectrum was identical in position with the bright line doublet observed in a flame fed with sodium chloride. Finally in 1859 KirchhofT formulated the modern concept of the composition of the sun based on the observed absorption lines in the solar spectrum. As a result of KirchhofT's theory much attention was at once turned to the examination and mapping of the emission spectra of terrestrial substances and testing for their presence in the solar atmosphere. Bunsen and KirchhofT proved the presence of m a n y terrestrial elements in the sun. Lockyer actually discovered one element, helium, in the sun almost thirty years before its discovery on the earth. Thus did qualitative spectral analysis enjoy a brilliant beginning. In the years that followed KirchhofT's work the spectroscope was properly credited with m a n y triumphs in the field of physics, but applications to chemical analysis were extended very little beyond simple qualitative detection of the elements. In 1882, however, Hartley performed quantitative analyses by determining at what concentrations in solutions the various spectral lines of metals would disappear.