Differential dichroic absorption

In the spectral region in which an optically active medium has an absorption band, the two circularly polarized components of plane-polarized light will also be differentially absorbed. As a result, the light will be el-liptically polarized and a CD spectrum can be obtained. A differential dichroic absorption. 

Fig. 16. Variation of the differential dichroic absorption (Ae) with chemical composition in copolymers of N-vinylcarbazole (NVC) with — — (—)-menthyl methacrylate (240 nm) —A— (—)-menthyl acrylate (257 nm) — — (—)-menthyl vinyl ether (265 nm)...

Table 2. Differential dichroic molar absorption coefficient (Ae) at different wavelengths for carbazole containing polypeptides... 

Equation (167) has been derived assuming the dichroic ratio S2(x) to be independent of the absorption coefficient of the polymer, and S2 per monolayer to be constant for any location within the LED, assumptions which may not always be justified. The relative EL output as a function of the distance from the A1 cathode can thus be obtained by differentiation of the measured relative emission from the parallel organized layer, fix), as given by the right-hand side of Eq. (167). The calculation of Afix)/Ax, made with Ax = 12 nm (10 monolayers) for the ITO/PPP/A1 devices with x varying between 0 and 120 nm, is shown in Fig. 62. Such a calculated profile, like that in single... 

Fig. 5.20. Return of different properties of elastase upon renaturation of denatured and reduced protein (A), enzyme activity ( ), antigenic activity ( ), differential absorption at 282 nm ( ), circular dichroic signal at 235 nm (O). chemical reactivity of Met 180 with [ " C]iodoacetamide, of Val 16 with [ C]acetic anhydride, and of Tyr 234 with [ C]dimethyl sulfate (from Ghelis, 1980).

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