The Nature of Electromagnetic Radiation

In the study of chemistry, the properties and composition of matter are investigated, along with the nature of electromagnetic radiation and how it affects matter. Electromagnetic radiation is radiant energy that exhibits wave properties and travels at the speed of light (when in a vacuum). 

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. 

In this chapter, we discuss the basic principles that are necessary to understand measurements made with electromagnetic radiation, particularly those deeding with the absorption of UV, visible, and IR radiation. The nature of electromagnetic radiation and its interactions with matter are stressed. The next four chapters are devoted to. spectroscopic instruments (Chapter 25), molecular absorption spectroscopy (Chapter 26), molecular fluorescence spectroscopy (Chapter 27), and atomic spectroscopy (Chapter 28). 

What are photons What role did Einstein s explanation of the photoelectric effect play in the development of the particle-wave interpretation of the nature of electromagnetic radiation ... 

Explain the nature of electromagnetic radiation and its interaction with matter... 

The nature of electromagnetic radiation baffled scientists for many years. At times light appears to behave like a wave at other times it behaves as though it were composed of small particles. While we now understand the wave-particle duality of all matter, including electromagnetic radiation, in terms of quantum mechanics, it is still convenient to consider electromagnetic radiation as having the properties of waves in many cases. 

V. Laue, X-ray interference, proves the nature of electromagnetic radiation and crystal structure and with it the structure of rigid macromolecules (metals, salts, minerals etc.)... 

It is assumed that the reader is broadly familiar with the properties of semiconductors, from which most detectors of importance are prepared, and with semiconductor technology which allows the preparation of interfaces such as p — junctions and Schottky barriers. For those who are not familiar with these concepts, many good books are available, including those by Sze [2.25], Grove [2.26], Kittel [2.27], and Moll [2.28]. It is also assumed that the reader is aware of the nature of electromagnetic radiation, including the properties of monochromatic and black body sources. For further information on this topic see the appropriate chapters in [2.1-7]. 

Which fundamental particles are important in chemistry The nature of electromagnetic radiation The photoelectric effect Wave-particle duality... 

The nature of electromagnetic radiation was described in terms of quanta or photons, and evidence for such a description is given from Planck s explanation of cavity radiation and the photoelectric effect. 

A fundamental paradox in the nature of electromagnetic radiation, to some extent apparent even in the earliest scientific studies by Newton and others, is that it exhibits not just wave-like but also particle-like (corpuscular) properties, and both prove to be of key importance in spectroscopy. In particular, it is only through the association of discrete units of energy with electromagnetic radiation of any given frequency that we can properly understand atomic and molecular transitions and the appearance of spectra. 

Optical property refers to a material s response to exposure to electromagnetic radiation and, in particular, to visible light. This chapter first discusses some of the basic principles and concepts relating to the nature of electromagnetic radiation and its possible interactions with solid materials. Then it explores the optical behaviors of metallic and nonmetal-lic materials in terms of their absorption, reflection, and transmission characteristics. The final sections outline luminescence, photoconductivity, and light amplification by stimulated emission of radiation (laser), the practical use of these phenomena, and the use of optical fibers in communications. 

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