Molar decadic absorptivity

The quantity e is called the absorption coefficient or extinction coefficient, more completely the molar decadic absorption coefficient it is a characteristic of the substance and the wavelength and to a lesser extent the solvent and temperature. It is coimnon to take path length in centimetres and concentration in moles per... 

Magnetic dipole moment of a molecule m, fJL Molar (decadic) absorption coefficient e... 

Uv—vis Spectra do not offer the unique group frequencies and fingerprinting abiUty of the it, but different chtomophotes exhibit absorptions at snecific wavelengths, A, and have characteristic intensities. These ate tabulated in handbooks as X and S, where S is a molar decadic absorption... 

The molar decadic absorption coefficient e is frequently called the extinction coefficient in published literature. Unfortunately numerical values of the extinction coefficient are often quoted without specifying units the absence of units usually means that the units are mol-1 dm3cm-1. See also [18]. The word extinction should properly be reserved for the sum of the effects of absorption, scattering, and luminescence. 

Molar (decadic) absorption coefficient L moF cm Molar (decadic) absorption coefficient m mol 0.1 -... 

The relation between the absorption cross section and the molar (decadic) absorption coefficient, e, (units cm ) is... 

Molar absorption coefficient, molar decadic absorption coefficient Absorbance divided by the absorption pathlength, I and the concentration, c ... 

The quadratic effect of an externally applied field on the absorption coefficient is described by the imaginary part of the third-order susceptibility -o) a),0,0). influences the molar decadic absorption coefficient of the solute. The absorption coefficient in the presence of the field is a quadratic function of the applied field strength (118),... 

Here, A is the (decadic) absorbance e represents the molar (decadic) absorption coefficient, customarily expressed in dm /mol cm, equivalent to 1000 cm /mol c stands for the concentration in mol/dm and I for the thickness of the sample in cm. These definitions are not strictly in accordance with SI standards. Nevertheless, they are used in this book, because millions of data in these units are published. The transmittance or transmittance factor is given by r = /[Pg.17]

In these equations, d is the sample thickness, e is the molar decadic absorption coefficient and c stands for the concentration. For pure samples, e-c should be replaced by a, which is the linear decadic absorption coefficient of the sample. For a black body radiator, the emission factor is ejf = 1. 

Actually existing emitters are not black bodies. More realistic values may be calculated according to the Planck-Kirchhoff law, Eqs. 3.3-4 to 3.3-8. Table 3.4-4 shows typical molar decadic absorption coefficients for infrared absorption bands of character-... 

Table 3.4-4 Infrared molar decadic absorption coefficients e. for vibrations of typical organic molecules (Jones and Sandorfy, 1956)...

Point (a) is best optimised by experiment, although several attempts have been made to provide a theoretical basis for determining the optimum concentration of a species of known molar decadic absorption coefficient for resonance Raman studies. The deleterious effects on the signal-noise ratio of the Raman spectram attributable to point (b) can be obviated by spinning the sample at ca. 1600 rev min as a solid, liquid or gas. Several articles contain details of many of these devices, the common object of which is to ensure relative motion between the sample and the focused laser beam (64). Surface scanning devices are also in use, and these enable the laser beam, while remaining focused on the surface of the sample, to scan over its surface in either a circular or linear fashion to achieve the same object. Such a procedure is particularly effective when the sample is held at liquid nitrogen temperatures. A device which allows this mode of operation is shown in Fig. 10 in this case the laser beam... 

Beer s law - An approximate expression for the change in intensity of a light beam that passes through an absorbing medium, viz., log(///j,) = -8c/, where is the incident intensity, I is the final intensity, e is the molar (decadic) absorption coefficient, c is the molar concentration of the absorbing substance, and / is the path length. Also called the Beer-Lambert law... 

As demonstrated above this system of linear equations can be simplified using vectors and matrices. The absorbances measured at the three wavelengths give the vector E. The concentrations of the three components A, B, and C produce the vector of concentrations a. Finally the nine molar decadic absorption coefficients of the three components at the three wavelengths of measurement form a matrix e in eq. (4.5), whereby... 

Consequently a measurement of the absorbances at some wavelengths is necessary. Knowledge of the molar decadic absorption coefficients at these wavelengths enables the vector of the concentrations of the reactants to be obtained at the chosen irradiation time. However, the inversion of the matrix causes some numerical problems. Therefore in the literature quite a few algorithms are described which try to successfully invert matrices even in the case of badly conditioned matrices of the absorption coefficients [39,41]. 

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