Electromagnetic waves, absorption

This relation for electromagnetic wave absorption can be presented numerically ... 

NMR spectroscopy means recording the electromagnetic wave absorption by a system of interacting nuclear magnetic dipole moments. If is important to note that the energy differences detectable by contemporary NMR equipment are of the order of 10 a.u., while the breaking of a chemical bond corresponds to about 10 a.u. This is why... 

The imaginary part, 8 (m), describes the electromagnetic wave absorption and is responsible for the energy loss of incident irradiation through the mechanism of electron polarization. The 8 (m) can be obtained by inserting the gradient of Eq. (18.1) into the relation [20, 21],... 

Zhizhin, G., Morozov, N., Moskalova, M., Sigarov, A., Shomina, E., Yakovlev, V., and Grigos, V. (1980). Surface electromagnetic wave absorption on copper surfaces with Langmuir films using CO2 laser excitation. Thin Solid Films, 70 163 -168. 

There are two principle ways for optical detection of protein concentrations either the macromolecule or its label emits energy (after excitation by light) -then a fluorescence signal can be measured or it absorbs energy from electromagnetic waves passing the sample - then the optical absorption of the sample can be measured by UV/Vis spectroscopy and concentrations can be calculated according to Lambert-Beers Law. 

In this section, we will study the absorption and emission probabilities for a single two-level atomic center that is illnminated by a monochromatic electromagnetic wave. 

J.-P. Berenger, A perfectly matched layer for the absorption of electromagnetic waves, Journal of Computational Physics 114, 185-200 (1994). 

As stated in the introductory chapter, we adopt a macroscopic approach to the problem of determining absorption and scattering of electromagnetic waves by particles. Therefore, the logical point of departure is the Maxwell equations for the macroscopic electromagnetic field at interior points in matter, which in SI units may be written ... 

There are many ways in which electromagnetic waves can interact with matter in its condensed phases, liquid and solid. Some of these have been treated with simple models in Chapter 9, and examples are given in this chapter. Lest we leave the reader with an oversimplified view of optical constants we list in Table 10.2 several absorption mechanisms in solids together with the spectral regions in which they are important. References, primarily review articles and monographs, are also included to guide the reader in further study. 

Electromagnetic waves behave like particles in photoelectric effect, Compton effect and phenomena of absorption and emission. The quantum of energy, E=Av, is called a photon. Photons travel with the speed of light c, and possess a momentum hv/c. 

There are numerous properties of materials which can be used as measures of composition, e.g. preferential adsorption of components (as in chromatography), absorption of electromagnetic waves (infra-red, ultra-violet, etc.), refractive index, pH, density, etc. In many cases, however, the property will not give a unique result if there are more than two components, e.g. there may be a number of different compositions of a particular ternary liquid mixture which will have the same refractive index or will exhibit the same infra-red radiation absorption characteristics. Other difficulties can make a particular physical property unsuitable as a measure of composition for a particular system, e.g. the dielectric constant cannot be used if water is present as the dielectric constant of water is very much greater than that of most other liquids. Instruments containing optical systems (e.g. refractometers) and/or electromechanical feedback systems (e.g. some infra-red analysers) can be sensitive to mechanical vibration. In cases where it is not practicable to measure composition directly, then indirect or inferential means of obtaining a measurement which itself is a function of composition may be employed (e.g. the use of boiling temperature in a distillation column as a measure of the liquid composition—see Section 7.3.1). 

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