Material absorption

6-2 Example Uniformly absorbing core 6-3 Example Nonunformly absorbing core 

For fibers with parameters of practical interest, the dominant effect of material absorption is the attenuation of total pulse power, together with a slight modification of pulse shape. The change in pulse shape is due to the fact that rays with larger inclinations to the fiber axis on step-profile fibers or with turning points closer to the interface of graded-profile fibers lose relatively more of their power to the cladding. 

When a dielectric material is absorbing, it is mathematically convenient to describe absorption by ascribing an imaginary component to the refractive index at each position. Hence, for slight absorption, we have 

To describe attenuation, we define P z) to be the power flowing within a narrow ray tube of rays, such as those illustrated in Fig. 4-1 and discussed at the beginning of Chapter 4. We then introduce the power attenuation coefficient y(z) of a ray defined by 

The power absorption coefficient a (r) does not vary along a cylindrically symmetric fiber. Thus, provided z is large compared to the ray half-period Zp, we can make an accurate approximation to the integrals in Eq. (6-7) by 

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M2 Thickener It is pulverized Ml thickener with an antimoisture substance (attasorb clay) added in the ratio of lp attasorb clay to 19p Ml thickener. It readily absorbs moisture from the air, but not to the extent of M1 thickener, because less air circulates thru the pulverized particles the attasorb clay further lowers moisture absorption. A container may be resealed after part of the M2 thickener has been used provided it has had minimum exposure to air. Since M2 thickener is composed mainly of Ml thickener, it retains most of the characteristics of Ml, including the disadvantages of being manufd from critical material, absorption of water from the air, and sensitivity to moisture. 

One way to control gaseous pollutants like SO2 and SO3 is to remove the gases from fuel exhaust systems by absorption into a liquid solution or by adsorption onto a solid material. Absorption involves dissolving the gas in a liquid while adsorption is a surface phenomenon. In each case, a subsequent chemical reaction can occur to further trap the pollutant. Lime and limestone are two solid materials that effectively attract sulfur dioxide gas to their surfaces. The ensuing chemical reaction converts the gaseous pollutant to a solid nontoxic substance that can be collected and disposed or used in another industry. 

The fundamental mode of a uniform lossless dielectric waveguide and, in particular, an MNF exists independently of its thickness. However, in practice, wave-guiding is limited by losses due to material absorption and geometric nonuniformities. For a very thin MNF, the transmission loss is primarily determined by input and output losses, which, in practice, cannot be reduced significantly11 64. As an example, Refs. 11 and 13 theoretically explored an MNF with adiabatically... 

Freely suspended liquid droplets are characterized by their shape determined by surface tension leading to ideally spherical shape and smooth surface at the subnanometer scale. These properties suggest liquid droplets as optical resonators with extremely high quality factors, limited by material absorption. Liquid microdroplets have found a wide range of applications for cavity-enhanced spectroscopy and in analytical chemistry, where small volumes and a container-free environment is required for example for protein crystallization investigations. This chapter reviews the basic physics and technical implementations of light-matter interactions in liquid-droplet optical cavities. 

Absorption is the assimilation of a chemical species into the interior of a solid material. Absorption may include the migration of solutes into internal pores (Fetter, 1993, 117) or the migration or exchange of atoms within the crystalline structure of a mineral (Krauskopf and Bird, 1995, 150). Some researchers use the generic term sorption to refer to a treatment method where adsorption and/or absorption are involved or if adsorption and absorption cannot be distinguished. 

Absorption plant a plant for recovering the condensable portion of natural or refinery gas, by absorbing the higher boiling hydrocarbons in an absorption oil, followed by separation and fractionation of the absorbed material. Absorption tower a tower or column which promotes contact between a rising gas and a falling liquid so that part of the gas may be dissolved in the liquid. 

When X-rays interact with any kind of materials, absorption and phase shifts effects occur. Conventional X-ray radiography relies on the absorption properties of the sample. The image contrast is produced by a variation of density, a change in composition or thickness of the sample, and is based exclusively on the detection of an amplitude variation of X-rays transmitted through the sample itself. Information about the phase of X-rays is not considered. The main limitation of this technique is the poor intrinsic contrast in samples with low atomic number (i.e., the case of soft matter ) or in materials with low variation of absorption from point to point. 

By examining the coupled equations, Eq. (3), it is clear that the maximum energy exchange occurs when = 90°. In the case of = 0, Beam 1 and Beam 2 will be uncoupled and Eqs. (3) become Beer-Lambert equations. Moreover, in the absence of material absorption, I2 is an increasing function of z if T is positive, while h is a decreasing function of z. This indicates that the energy can be transferred from Beam 1 to Beam 2. The direction of energy transfer is... 

Direct or substantive dyes are colored compounds that are mainly used to dye materials made from natural or regenerated cellulose (e.g., cotton, jute, viscose, or paper) without employing mordants as auxiliaries. The essential requirement for classification of a dye in this group is its substantivity, i.e., its absorption from an aqueous salt-containing solution onto cellulosic materials. Absorption onto cotton takes place in a neutral to soda alkaline medium, and onto paper in a weakly acid to neutral medium. 

We can think of electromagnetic modes between the two bodies as the fluctuations that remain as tiny deviations from the outer turmoil. The extent of the quelling is, obviously, in proportion to the material-absorption spectra. So we can think of absorption frequencies in two ways those at which the charges naturally dance those at which charge polarization quells the vacuum fluctuations and stills the space between the surfaces.13... 

Level 1, the introduction, speaks the language of the modern theory in order to help you develop intuition about the fundamental connection between material absorption spectra and charge-fluctuation forces. Its approximate formulae also show the connection between the shapes of bodies and the forces between them. 

The molecular sieves are aluminosilicates of particular importance. They are crystalline materials that have open structures that contain pores and channels that have molecular dimensions. This family of materials includes the zeolites, which have numerous applications in heterogeneous catalysis, ion-exchange materials, absorption of molecular species, and gas separation. While some zeolites occur naturally, they are usually manufactured from silicon and aluminum oxides mixed with tetraaUcylammonium templates in a high-pressure autoclave (see Zeolites). 

Interactions of pump and probe pulses with a material absorption are usually described by density matrix equations for a distribution of two-level or three-level systems. The formulation of these equations can be found in textbooks and other reviews [8,9]. We try here simply to describe in physical terms the ways in which the different parameters of the equations manifest themselves experimentally. The simplest theoretical case is the two-level system, in which is the dephasing time of the coherently induced electronic polarization and Tj is the energy relaxation time. We begin our discussion by simplifying even further and assuming that Tj is very short compared to the optical pulse durations. Then, the coherent polarization follows the optical... 

Photothermal poling [ 140,141 ] is a simple modification of the electrode poling technique. The only difference is the use of a laser beam, with wavelength lying in the material absorption band, to heat the thin film. The main advantage of this technique consists of a very localized poling. It has been used for the fabrication of bidirectionally poled polymer films [141]. 

After injection of the extraction from the testing material, absorption peaks appear at different retention times (RT). Under fixed HPLC conditions, a specific compound has a fixed retention time. By comparing the retention time and the peak area of the extraction from the testing material with the standard azo dyes (aromatic amines) at the known concentration, we can confirm the type and the quantity of the azo dyes existing in the testing material. According to the Directive 2002/61/ EC, the listed azo dyes (aromatic amines) should be below 30 mg kg in the testing materials. 

Photoacoustic spectroscopy is often the most appropriate form of optical spectroscopy when material absorption is weak. ISLS spectroscopy offers the advantages of photoacoustic detection in a geometry that is compatible with the requirements of a DAC. The ISLS approach enables the experimenter to tune in material modes for observation, by adjustment of the excitation pulse width and wavelength. Control of the probe wavelength permits... 

In an indoor climate context, sorption is the term used for the surface processes adsorption, absorption, and desorption. Adsorption is the accumulation of a chemical substance from the gas phase on the surface of a solid building material. Absorption is the... 

EXPOSURE ROUTES Inhalation ingestion (migrates to food from packing materials) absorption. 

This principal of communion through material absorption was so well accepted that later on, in the fourteenth century, the Templars were accused of drinking the ashes of their dead Brothers mixed in wine and the blood of a black car ... 

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