The Reversing Pulse Technique in Electric Birefringence

Tinoco, Ignacio; Yamaoka, Kiwamu

doi:10.1021/j150573a020

Cited by 157 publications

(75 citation statements)

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“…In rapidly reversing electric fields, macromolecules oriented by fast induced dipole mechanisms exhibit no transients at field reversal.24 However, if the macromolecule has a permanent dipole moment parallel to its long axis, a minimum is observed in the birefringence upon reversal of the electric field. 24 The depth of the minimum can be used to calculate the ratio P / Q , according to Eq. (6):…”

Section: Experimental Theory Of the Methodsmentioning

confidence: 99%

“…6 5~~ ( 7 ) where ?D is the rotational diffusion time of the macromolecule, here called the decay time. 24 If slow induced dipole effects are important (i.e., slow polarization processes for which the time constants are of the same order of magnitude as the rotational diffusion time), the above equations are incomplete, and terms involving the relaxation time of the slow induced polarizability must be added to Eq. ( 6 ) .…”

Section: Experimental Theory Of the Methodsmentioning

confidence: 99%

“…( 6 ) . 24 The equations of Tinoco and YamaokaZ4 have been improved by Takezoe and Yu25 and by Szabo et a1. 26 The latter authors have treated the coupled rotational and ion atmosphere dynamics of a rod-like macromolecule with no permanent dipole moment.…”

Section: Experimental Theory Of the Methodsmentioning

confidence: 99%

“…'~ In the calculation, the ratio of the two polarizabilities (in the terminology of Ref. 24) q1 / q2 was set equal to 2, and the relaxation times of the two polarizabilities were assumed to be equal and equal to 0.5 T D . The theoretical and experimental curves are compared in Figure 12.…”

Section: Field2631 334243mentioning

confidence: 99%

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Transient electric birefringence of two small DNA restriction fragments of the same molecular weight

Stellwagen

1991

Biopolymers

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The transient electric birefringence of two small DNA restriction fragments of the same molecular weight, one of which migrates anomalously slowly on polyacrylamide gels, has been investigated. Both fragments exhibit negative birefringence. The decay of the birefringence of the anomalously slowly migrating fragment is 8-9% faster than that of the normally migrating fragment. The faster birefringence decay of the anomalous fragment 12A persists under a variety of buffer conditions, suggesting that it is due primarily to static bending and/or curvature of fragment 12A. In reversing electric fields the absolute amplitude of the birefringence of fragments 12A and 12B decreased about 26% before returning to the steady state value. The minimum in the birefringence occurred faster than expected from the birefringence decay times and decreased with increasing electric field strength, suggesting that the minimum is due to a slow polarization of the ion atmosphere. For both fragments, the rise of the birefringence in the Kerr region is about 10% slower than the field-free decay. The buildup of the negative birefringence is preceded either by an interval when no birefringence is observed or by a small positively birefringent transient, suggesting that a small transverse ionic polarizability is also present. Both DNA fragments exhibit Kerr law behavior over most of the range of electric field strengths investigated. Analysis of the shapes of the saturation curves suggests that differences may exist in the polarization mechanisms of the two fragments.

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Section: Experimental Theory Of the Methodsmentioning

confidence: 99%

Section: Experimental Theory Of the Methodsmentioning

confidence: 99%

Section: Experimental Theory Of the Methodsmentioning

confidence: 99%

Section: Field2631 334243mentioning

confidence: 99%

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Transient electric birefringence of two small DNA restriction fragments of the same molecular weight

Stellwagen

1991

Biopolymers

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“…22 ratio of(f3w) 2 /2yw, i.e., (!1w) 2 /kT11rxw, and hence, to the mechanism of electric field orientation and the helical structure of [Glu(OBzl)]"' 22 • 23 Qualitatively, the larger the value for the depth, i.e., 1 -11m, the greater is the contribution of the permanent electric dipole moment to the field orientation. 22 -27 The value of the depth is larger in 2-chloroethanol and cyclohexanone 0.06---0.08) than in pyridine In chloroform, the value of 11m lowers from ca.…”

Section: Field-on Processesmentioning

confidence: 99%

Reversing-Pulse Electric Birefringence of Poly(γ-benzyl L-glutamate) IV. Electric, Optical, and Hydrodynamic Properties in Helix-Forming Solvents as Evaluated from Field-On and Field-Off Processes

Yamaoka

Yamamoto

Kosako

1987

Polym J

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ABSTRACT:Reversing-pulse electric birefringence (RPEB) of poly(y-benzyl L-glutamate), [Giu(OBzl)]., with a weight-average molecular weight of 1.71 x 10 5 was measured at 20'C and at 535 nm in four helix-forming solvents: 2-chloroethanol, cyclohexanone, pyridine, in which [Giu(OBzl)]. is dissolved molecularly, and chloroform in which it is aggregated. A standard analytical procedure is given for the RPEB signal which represents the field-on and field-off processes. The steady-state birefringence of [Giu(OBzl)]. was measured over a wide field strength range up to ca. 20 kV em_,_ The Kerr law was obeyed at low fields, while a saturating trend was observed at higher fields. Specific and intrinsic Kerr constants were obtained. The weight-average molecular length /w, the degree of polydispersity lwll., and the electric parameter (f3w) 2 12rw were evaluated from the reverse-transient signal which exhibits a deep minimum. The values of lw and lwll. in the field-off process were also evaluated from the birefringence-average relaxation time and initial slope, both of which were obtained from the decay signal. The axial translation per residue of the [Giu(OBzl)]. helix was found to range between 1.27 and 1.30 A at dilute concentrations regardless of solvent.

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Electro-optic studies of polymers of varying flexibility in solution

Nwammuo¹,

Maitland

1999

Angew. Makromol. Chem.

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By use of rectangular and reversing pulse electric birefringence techniques, the electrical properties of polymers of intermediate degrees of flexibility were studied. The effects of chain flexibility, interactions, temperature and solvent on the electrical properties of seven selected polymers are covered. In all the cases the concentration‐field dependence is exponential. There is also considerably deviation from the Kerr law as the field is increased. The Kerr constants are measured for some systems for the first time while results for others are in good agreement with similar systems studied in the past. For fairly rigid polymers the Kerr constant variation with concentrations is of the form B ∝ Cζc where the exponent ζc is 2.0 for monodisperse poly(γ‐benzyl‐L‐glutamate) and 0.4 for polydisperse poly(n‐butyl isocyanate), respectively. For the flexible coil polymers the Kerr constants varied linearly with concentration. The other electrical properties, such as the dipole moments and the polarisability anisotropies for the systems show marked concentration and molecular weight dependence.

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The Reversing Pulse Technique in Electric Birefringence

Cited by 157 publications

References 1 publication

Transient electric birefringence of two small DNA restriction fragments of the same molecular weight

Transient electric birefringence of two small DNA restriction fragments of the same molecular weight

Reversing-Pulse Electric Birefringence of Poly(γ-benzyl L-glutamate) IV. Electric, Optical, and Hydrodynamic Properties in Helix-Forming Solvents as Evaluated from Field-On and Field-Off Processes

Electro-optic studies of polymers of varying flexibility in solution

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