KIRCHHOFF AND BUNSEN
Following the invention of the clean-flame burner by the German chemist Robert Bunsen (1811-1899) it was possible to study the effect of different chemical vapours on the known pattern of spectral lines. Together, Gustav Kirchhoff and Bunsen invented a new instrument called spectroscope to measure these effects. Within a few years, they had managed to isolate the spectra for many known substances, as well as discovering a few unknown elements.
To prove his laws of spectral analysis, Kirchhoff used sodium gas to show that when white light is directed through the gas, the characteristic colour of the sodium is absorbed and the spectrum shows black lines where the sodium should have appeared. In the experiment shown above, shining white light through a lens produces a continuous spectrum. When a petri dish of the chemical potassium permanganate in solution is place between the lens and the light (below), some of the color of the spectrum is absorbed.
SPECTRUM OF THE STARS
By closely examining the spectral lines in the light received from a distant star or planets, the astronomers can detect these "fingerprints" and uncover the chemical composition of the object being viewed. Furthermore, studying the spectral lines can also discover the heat of the source. Temperature can be measured by the intensities of individual lines in their spectra. The width of the line provides information about temperature, movement, and presence of magnetic fields. With magnification, each of these spectra can be analyzed in more detail.