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Light scattering of aqueous solutions of DNA, poly(acrylic acid), and tobacco mosaic virus under alternating electric field
Author(s) -
Fujikado Takashi,
Hayakawa Reinosuke,
Wada Yasaku
Publication year - 1979
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1979.360180917
Subject(s) - electric field , dielectric , relaxation (psychology) , chemistry , tobacco mosaic virus , acrylic acid , dipole , amplitude , scattering , nuclear magnetic resonance , optics , polymer , molecular physics , analytical chemistry (journal) , optoelectronics , materials science , physics , organic chemistry , virus , psychology , social psychology , monomer , quantum mechanics , virology , biology
Two new techniques, amplitude modulation (AM) and frequency modulation (FM) of an electric field, are developed for the light‐scattering study of polymer solutions under ac electric fields. The AM technique makes it possible to observe accurately the frequency dependence of the intensity changes of scattered light due to the electric field. The FM one allows us to obtain directly the frequency derivative of the intensity change. The techniques are applied to DNA, poly(acrylic acid), and tobacco mosaic virus in the frequency range from 10 Hz to 100 kHz. A low‐frequency relaxation is found for both DNA and poly(acrylic acid). The obsersved relaxation time of DNA agrees with that in the dielectric relaxation of DNA, which has been attributed to the rotation of the molecule with a quasipermanent dipole. In the case of poly(acrylic acid), the relaxation strength increases with increasing degree of neutralization. TMV at a concentration of 0.1% exhibits a negative relaxation at low frequencies, which indicates the rotation of TMV aggregate with a permanent dipole along its minor axis.