Polysilanes circular dichroism

Fluorescence spectroscopy in combination with circular dichroism (CD), optical rotatory dispersion. X-ray crystallography, UV and NMR spectroscopy of the main chain is a powerful probe for identifying helical conformation, uniformity, and rigidity in polymers. In recent years, these techniques have been applied extensively to investigate the structures of polysilanes in both the solid state and in solution and it is now clear that after electronic structure main chain helicity is the principal determinant of the properties of polysilanes. In... 

Although most polysilanes adopt main-chain helical structures, most of them do not show a preferred screw sense. Thus, if a helical polymer shows a preferred screw sense it can be either left-handed or right-handed type. These possibilities can be detected by CD (circular dichroism) spectroscopy. Thus, in regular optical absorption spectroscopy the extinction coefficient or molar absorptivity (e) is related to the absorbance (A), concentration (c) and path length of the detecting cell (1) by the famous Beer-Lambert s expression (see Eq. 7.17). 

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