Ranging from the physics of elementary particles to the structure of viruses, the subject matter of this book stresses the importance of optical activity and chirality in modern science and will be of interest to a wide range of scientists. Using classical and quantum methods with a strong emphasis on symmetry principles, the volume develops the theory of varied optical activity and related phenomena from the perspective of molecular scattering of polarized light. First Edition Hb (1983): 0-521-24602-4

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Molecular Light Scattering and Optical Activity

Aqueous solutions of blockcopolymers, consisting of a polyoxypropyleneblock (POP) with a polyoxyethylene-block (POE) at each side, were studied using surface and interfacial tension measurements, static and dynamic light scattering and smallangle neutron scattering techniques, electric birefringence, rheological and DSC-measurements. The compounds were commercial samples and had an approximate average composition EO20PO70EO20, EO18PO58EO18, and EO106PO69EO106. All three compounds formed micelles above a critical concentration. The size of the micellar core is determined by the length of the hydrophobic poly-propyleneoxide block. The transfer energy of a propyleneoxide unit from the aqueous to the micellar phase is about 0.3 kT at room temperature and hence a quarter of the corresponding value for a CH2-group.

The aggregation behavior of poly-(oxyethylene)-poly-(oxypropylene)-poly-(oxyethylene)-block-copolymers in aqueous solution

This review will consider solution studies of structure and interactions of DNA and DNA complexes using linear dichroism spectroscopy, with emphasis on the technique of orientation by flow. The theoretical and experimental background to be given may serve, in addition, as a general introduction into the state of the art of linear dichroism spectroscopy, particularly as it is applied to biophysical problems.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/9977D4B0B0D355FEDE0371EB4CB78BBC/S0033583500004728a.pdf/div-class-title-linear-dichroism-spectroscopy-of-nucleic-acids-div.pdf

Linear dichroism spectroscopy of nucleic acids.

The absorption, fluorescence, dichroism, and birefringence of stained squid axons were measured during action potentials and voltage clamp steps in an effort to find large optical signals that could be used to monitor membrane potential. Changes in all four optical properties were found that were linearly related to membrane potential and, with several new dyes, the signal-to-noise ratios were larger than any obtained previously. The problem of photodynamic damage was greatly diminished; with a merocyaninerhodanine dye, the photodynamic damage associated with intense light and the presence of oxygen was negligible. The absorption change obtained with this dye was relatively large; it could be measured with a signal-to-noise ratio of 100∶1 during a single action potential.

Changes in absorption, fluorescence, dichroism, and birefringence in stained giant axons: Optical measurement of membrane potential

Aqueous solutions of blockcopolymers, consisting of a polyoxypropylene- block (POP) with a polyoxyethylene-block (POE) at each side, were studied using sur- face and interfacial tension measurements, static and dynamic light scattering and small- angle neutron scattering techniques, electric birefringence, rheologlcal and DSC-meas- urements. The compounds were commercial samples and had an approximate average composition EO20PO70EO20, EOlsPOssEOI8, and EO106POegEO106. All three com- pounds formed micelles above a critical concentration. The size of the micellar core is determined by the length of the hydrophobic poly-propyleneoxide block. The transfer energy of a propyleneoxide unit from the aqueous to the micellar phase is about 0.3 kT at room temperature and hence a quarter of the corresponding value for a CH2-grou p. The aggregation number of the miceUes increases strongly with increasing tempera- ture while the hydrodynamic radius remains constant in first approximation. The small- angle neutron scattering (SANS) data show at higher concentrations a strong correlation peak. Both the SANS- and the light-scattering data can be interpreted on the basis of the theory of hard sphere particles. Solutions with a volume fraction beyond about 0.2 gellifie when the temperature is raised above a characteristic value that is at the lowest concentrations slightly above room temperature, shift to lower values with increasing concentrations. Below this gelation temperature DSC-measurements show a phase transition with enthalpies between 40 J/g and 80 J/g, which is probably due to the dehydration of the PO-groups; this transkion can also be observed at low concentrations where no gelation takes place. The position of the correlation peak of the SANS-data is not affected by the gel formation~ Some samples, however, show clear evidence of long-range order and seem therefore to consist of cubic liquid crystalline phases. The shear moduli of the gels can qualitatively be understood on the basis of hard sphere models.

http://rd.springer.com/content/pdf/10.1007%2FBF01513189.pdf

E. Fredericq

Papers

Electric dichroism and electric birefringence