Light, nature electromagnetic spectrum

Spectroscopy, or the study of the interaction of light with matter, has become one of the major tools of the natural and physical sciences during this century. As the wavelength of the radiation is varied across the electromagnetic spectrum, characteristic properties of atoms, molecules, liquids and solids are probed. In the... 

Neodymium and YAG Lasers. The principle of neodymium and YAG lasers is very similar to that of the ruby laser. Neodymium ions (Nd +) are used in place of Cr + and are often distributed in glass rather than in alumina. The light from the neodymium laser has a wavelength of 1060 nm (1.06 xm) it emits in the infrared region of the electromagnetic spectrum. Yttrium (Y) ions in alumina (A) compose a form of the naturally occurring garnet (G), hence the name, YAG laser. Like the ruby laser, the Nd and YAG lasers operate from three- and four-level excited-state processes. 

Understanding the nature of atoms and molecules begins with an understanding of light and other kinds of electromagnetic radiation that make up the electromagnetic spectrum. An... 

Light can be narrowly defined as the visible portion of the electromagnetic spectrum. A broader definition would include infrared, ultraviolet, and x-ray wavelengths, which are not visible to the eye. The nature of light has been the subject of controversy for thousands of years. Even today, while scientists know how light behaves, they do not always know why light behaves as it does. 

Low-level visible light that is naturally present may be amplified and presented directly to the viewer s eye. (Light in the near-infrared part of the electromagnetic spectrum [ 0.77-1.0 microns], either naturally present or supplied as illumination, may also be amplified and its pattern translated into a visible-light pattern for the viewer s benefit.) This technique is termed image intensification. 

Photosensitivity is a common adverse effect of the fluoroquinolones. It results from an abnormal reaction of the skin to natural or artificial light sources, usually associated with the UVA part of the electromagnetic spectrum (315-400 nm), mediated by the absorption of light energy into fluoroquinolones, followed by degradation of the molecule and formation of cytotoxic photoproducts (64). 

The color of minerals is one of their most fascinating properties and is frequently the first thing that draws attention to the mineral. Color can originate in a number of ways from the presence of a cation or anion that is colored, from the presence of an impurity that is colored, or from a defect in the arrangement of the ions in the solid. The color is always a result of the transition of electtons in the ions or the crystal lattice from one energy level to another. Before we explain this movement of electrons we need to review the nature of light and the electromagnetic spectrum. 

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