Electromagnetic radiation classifications

When this emission originates from living organisms or from chemical systems derived from them, it is named bioluminescence (BL). Both phenomena are luminescence processes that have been traditionally distinguished from related emissions by a prefix that identifies the energy source responsible for the initiation of emission of electromagnetic radiation. Based on Wiedemann s classification, which was discussed in Chapter 1, contemporary luminescence processes have been added to the list of luminescence phenomena, as can be seen in Table 1. 

So far as the classification of the type of spectroscopy performed is concerned, the characterisation of the dynamical motions of the nuclei and electrons within a molecule is more important than the region of the electromagnetic spectrum in which the corresponding transitions occur. However, before we come to this in more detail, a brief discussion of the nature of electromagnetic radiation is necessary. This is actually a huge subject which, if tackled properly, takes us deeply into the details of classical and semiclassical electromagnetism, and even further into quantum electrodynamics. The basic foundations of the subject are Maxwell s equations, which we describe in appendix 1.1. We will make use of the results of these equations in the next section, referring the reader to the appendix if more detail is required. 

Fig. 3.8 Classification of electromagnetic radiation in the wavelength range below X of 1200 nm as bands with specific names, and the interaction with molecules M (VUV vacuum-UV).

Tab. 3.9 Classification of terms used to describe and measure electromagnetic radiation either received by a defined surface element or emitted by a surface element of a radiant source (for verbatim definitions refer to Serpone and Emeline, 2002, Bolton, 2000, 1999, Verhoeven, 1995, McCluney, 1994, Mills et al., 1993, Braun et al., 1991, and the glossary in this book)...

Classification of electromagnetic radiation. Spectrum adapted by permission from C. W. Keenan, D. C. Kleinfelter, and J. H. Wood, General College Chemistry, Sixth Edition, Harper Row Publishers, Inc., 1980. 

Photochemistry is inherently related to photophysics, the study of those radiative and nonradiative processes that convert one electronic state into another electronic state without chemical change. Central to both photochemistry and photophysics is the classification of UV-vis radiation in terms of its energy. Because electromagnetic radiation is quantized, it has properties like those of a particle, and a mole of photons is called an einstein. Electromagnetic radiation also has the properties of a wave, and equation 12.1 gives the relationship between the energy of UV-vis radiation in kcal/mol and its wavelength in run. ... 

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