Diffraction of electromagnetic radiation

Diffraction of electromagnetic radiation by atoms and molecules occurs when the wavelength of the electromagnetic radiation is similar to the size of the particle that causes the diffraction—in this case, atoms or molecules, (a) Using 2.0 X 102 pm as the diameter of an atom, decide what type(s) of... 

Fig. 7.2. Diffraction of electromagnetic radiation by planes of atoms in a crystalline solid.

The planes of motifs in a crystal thus act essentially as diffraction gratings (Bueche, 1986). Diffraction of electromagnetic radiation by crystals can occur only when the wavelength of the radiation is of the same order of magnitude as the regular repeat distance between motifs. This is the basis of the usefulness of using X-rays to determine crystal structure. 

The Fourier transform (FT) is ubiquitous in science and engineering. For example, it finds application in the solution of equations for the flow of heat, for the diffraction of electromagnetic radiation, and for the analysis of electrical circuits. The concept of the FT lies at the core of modern... 

X-ray spectroscopy, like optical spectroscopy, is based on measurement of emission, absorption, scattering, fluorescence, and diffraction of electromagnetic radiation. X-ray fluorescence and X-ray absorption methods are widely used for the qualitative and quantitative determination of all elements in,the periodic table having atomic numbers greater than that of sodium. With special equipment, elements with atomic numbers-in the range of 5 to 10 can also be determined. 

We noted some details of basic electronic circuits and diffraction of electromagnetic radiation. LiF was mentioned as a crystal for use as an x-ray difiraction device. 

You can appreciate why scientists were puzzled The results of some experiments (the photoelectric effect) compelled them to the view that electromagnetic radiation is particlelike. The results of other experiments (diffraction) compelled them equally firmly to the view that electromagnetic radiation is wavelike. Thus we are brought to the heart of modern physics. Experiments oblige us to accept the wave-particle duality of electromagnetic radiation, in which the concepts of waves and particles blend together. In the wave model, the intensity of the radiation is proportional to the square of the amplitude of the wave. In the particle model, intensity is proportional to the number of photons present at each instant. 

The physical basis of spectroscopy is the interaction of light with matter. The main types of interaction of electromagnetic radiation with matter are absorption, reflection, excitation-emission (fluorescence, phosphorescence, luminescence), scattering, diffraction, and photochemical reaction (absorbance and bond breaking). Radiation damage may occur. Traditionally, spectroscopy is the measurement of light intensity... 

The techniques available to achieve molecular structure determinations are limited. They include structural analysis with diffraction techniques—such as electron, neutron, and x-ray diffraction—and various absorption and emission techniques of electromagnetic radiation—such as microwave spectroscopy and nuclear magnetic resonance (NMR). For molecules with unpaired spins a companion technique of electron spin resonance spectroscopy (ESR) is highly informative. 

De Broglie s hypothesis of matter waves received experimental support in 1927. Researchers observed that streams of moving electrons produced diffraction patterns similar to those that are produced hy waves of electromagnetic radiation. Since diffraction involves the transmission of waves through a material, the observation seemed to support the idea that electrons had wave-like properties. 

Measurement of the quantity and quality of electromagnetic radiation emitted, reflected, transmitted, or diffracted by the sample. 

Virtually all parts of the spectrum of electromagnetic radiation, from x rays to radio waves, have some practical application for the study of organic molecules. The use of x-ray diffraction for determination of the structures of... 

Studies of black-body radiation led to Planck s hypothesis of the quantization of electromagnetic radiation. The photoelectric effect provided evidence of the particulate nature of electromagnetic radiation diffraction provided evidence of its wave nature. 

Figure 3.l5d shows the structure of sodium chloride as determined by the X-ray diffraction technique. The study of crystals using X-ray diffraction was pioneered by Sir William Bragg and his son Sir Lawrence Bragg in 1912. X-rays are a form of electromagnetic radiation. They have a much... 

A spectroscope is an instrument used to disperse a beam of electromagnetic radiation into its component waves. Many spectroscopes have diffraction gratings that separate the waves, which are beamed to a mirror and reflected back to the eye of an observer. Each wave appears as a separate colored line. 

In summary In diffraction of any form of electromagnetic radiation by a regularly repeating series of identical objects (e.g., a series of slits). 

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