Brownian dynamics of weakly bendable macromolecules: Effects of bending fluctuations on electric dichroism

The expression of the steady-state value of electric dichroism (ED), over the entire electric field strength, for semistiff linear polymers with an electric polarizability along the chain has been derived by a normal mode approximation on the basis of the Brownian dynamics. Only a flexibility parame...

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Veröffentlicht in:The Journal of chemical physics 1995-06, Vol.102 (24), p.9700-9708
1. Verfasser: Fukudome, Kiyohiro
Format: Artikel
Sprache:eng
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Zusammenfassung:The expression of the steady-state value of electric dichroism (ED), over the entire electric field strength, for semistiff linear polymers with an electric polarizability along the chain has been derived by a normal mode approximation on the basis of the Brownian dynamics. Only a flexibility parameter, L/P defined as the contour length L to the persistence length P, is introduced into the expression without any assumption of the configuration. Our ED theory predicts that, with the increase in an L/P value, the steady state value is decreased over a low-to-medium field strength range but remains to be unchanged at infinitely high fields. The expression of the ED relaxation after the removal of an electric field is also derived, when the field strength is low. The off-field relaxation decays multiexponentially not only due to rotational diffusion but also due to bending diffusion. The contribution of the bending to the decay amplitude is increased with increasing L/P. The flexibility strongly affects the transient state, i.e., the rotational and bending relaxation times and their amplitudes rather than the steady state.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.468789