Simple absorption spectrograph

In order to focus our attention we now outline the basic essential features of a microwave absorption spectrometer, and then examine the constituent parts in more 

During the past fifty years extensive effort in many laboratories has led to enhancements of the simple system, turning microwave spectroscopy into an extremely sensitive and versatile tool. We now review some of these developments. We shall also describe the essential features of a radio telescope because almost thirty diatomic molecular species, many of which would be transient species in the laboratory, have been detected in interstellar gas clouds. Molecular radio astronomy is closely linked with and complementary to laboratory microwave spectroscopy. Or, if you wish, you can reverse the emphasis of that last statement  

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In 1929 spectroscopic examination of the absorption bands of oxygen led Giauque and Johnston to conclude that it is not a simple gas but contains three isotopes of atomic weights (16), (17) and (18). The two latter are present in only small amount, nevertheless their existence has been confirmed by the mass spectrograph. Atmospheric oxygen contains these isotopes in the proportions of 99 76 of isotope (16), 0-04 of (17) and 0-20 of (18). 

The detection limits for cobalty nickel, and lead in aqueous solution by atomic absorption are about 50 fig. per liter. Normally these elements occur at lower concentrations in fresh waters, and direct measurement by atomic absorption is not possible. A rapid, simple, accurate, and sensitive chelation-extraction method for determining lead, cobalt, and nickel is attained by chelating the metals with ammonium pyrrolidine dithiocarbamate at a pH of 2.8, extracting the metal-chelates with methyl isobutyl ketone, and aspirating the ketone layer. Results obtained by this method agreed well with results obtained by spectrographic methods. As little as 1 fig. of lead, cobalt, and nickel per liter can be detected. This is at least one order of magnitude lower than most other wet chemical procedures. 

For example, in [5] for this purpose authors have carried out the research of the X-ray absorption spectra of the Ti doped complicated oxides in CoO-MnO-02 system with the direct and return spinels structures. All these compounds spectra have been compared with those of simple oxides containing ions Mn in various valence states. These spectra were registered during 6-12 hours by vacuum spectrograph. 

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