Electromagnetic spectrum description

The absorption or emission of energy in an electromagnetic spectrum occurs in discrete packets of photons. The relationship between the energy of a photon and the frequency appropriate for the description of its propagation is given by the famous Bohr equation ... 

Figure 4-2. Electromagnetic spectrum on a logarithmic scale, indicating the wavelengths and the frequencies together with their qualitative description. The wavelengths and colors of visible light (see Table 4-1) are emphasized.

In the spectrophotometric method, color is assessed by means of a standard absorption spectrophotometer. In this case, a description of the hue, intensity and brightness of a non-turbid colored solution is possible in the visible region (400-700 mn) of the electromagnetic spectrum. Since pH will have a significant impact on the color of certain dyes, the pH of the dye solution employed must be measured and reported. Details regarding the method are provided in section 2120 C of the Standard Methods book, and can be summarized as follows ... 

An online resource on this topic is available at (30). This webpage was developed by Aeree Chung and Ben Johnson at Columbia University in conjunction with their astronomy lab. The pages give an overview of the electromagnetic spectrum, and outline applications of spectroscopy to astronomical studies. Included are pictorial representations of astronomical observations with brief descriptions, and information on observational instrumentation. Also discussed are the distinctions between continuum,... 

Abstract This chapter presents a description of the interstellar medium. It starts with a summary of the interstellar medium stmcture and how the various phases are related to each other. The emphasis is put on molecular clouds, and on their densest regions, the dense cores, which are the birth place of stars. The evolution of matter during the star formation process and its observable consequences, especially in term of chemical composition is presented. The next section is dedicated to the constituents of the interstellar medium, with separate presentations of the gas species and the dust grains. Methods used by astronomers to derive useful information on the structure, temperature, ionization rate of interstellar environments as well as magnetic fields are briefly described. The last part of the chapter presents the telescopes and their instruments used for studying the interstellar medium across the electromagnetic spectrum. 

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