Extinction coefficient, theoretical relationship

The extinction coefficient for non-ahsorbing particles may be theoretically evaluated from the ligjit scattering theory developed by Mie (lU, 1 ). It is calculated from the relationship... 

The experimentally verified theoretical relationship for the extinction coefficient ae is given by... 

In this section we shall analyze the relationship between the electronic structures and the absorption intensities in details. The intensity of the electronic transition is experimentally obtained as an area of the absorption spectrum displ ed with the abscissa of the energy linear scale(for example cm , eV,etc.) and the ordinate of the molar extinction coefficients and the experimental value corresponds to the theoretically obtained oscillator strength of the electronic transition. The example is shown in Fig.3. ... 

A theoretical basis for this relationship is the Beer-Lambert law, which expresses the extinction coefficient in terms of the concentration of light-absorbing material. For dense algal cultures, this law has been experimentally verified (33). A similar relationship based on this law has been proposed by Chen (12) from the data of Azad and Borchardt (34)... 

Likewise, quantum mechanical calculation succeeds in giving a theoretical explanation of some facts that the resonance theory could not explain, for example, why bis(pyridine-2)monomethine cyanine and bis(pyridine-4)monomethine cyanine possess the same lowest energy transition contrary to the 2,2 - and 2,4 -quinoline monomethine dyes, together with a molecular coefficient extinction lower than that of the 4,4 -quinoline dye (11). Calculation shows also that there is no theoretical reason for observing a relationship between and pK in a large series of dyes with different nuclei as it has been postulated, even if limited observations and calculations in short homogeneous series could lead to this conclusion (105). 

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