S. Chandrasekhar

Bio: S. Chandrasekhar is an academic researcher from Raman Research Institute. The author has contributed to research in topics: Liquid crystal & Biaxial nematic. The author has an hindex of 31, co-authored 124 publications receiving 3368 citations. Previous affiliations of S. Chandrasekhar include Royal Institution & University of Mysore.

Cholesteric Liquid Crystals

Abstract: For light propagating along its optic axis, the cholesteric liquid crystal possesses a very high optical rotatory power, usually a few orders of magnitude larger than that of an ordinary optically active liquid. When the wavelength of the light in the medium is equal to the pitch P of the helical structure, Bragg reflection takes place. The reflected light is strongly circularly polarized; one circular component is almost totally reflected over a spectral range of some 100 A while the other passes through practically unchanged. In the neighborhood of the region of reflection, the rotatory dispersion is anomalous and the sign of the rotation is opposite on opposite sides of the reflected band. The behavior is not unlike that of an optically active molecule in the vicinity of an absorption, except that in this case the anomalous rotatory dispersion is present even when the molecules are nonabsorbing.

High pressure studies on ferroelectric liquid crystals

Abstract: In contrast to the wealth of data available on ferroelectric liquid crystals at atmospheric pressure, only a few reports of studies at high pressure exist. We have undertaken systematic high pressure studies of the properties of these materials. In this paper the results of detailed measurements of spontaneous polarisation and transverse static dielectric constant as functions of pressure for two different compounds exhibiting low and high values of polarisation are presented.

Nematic Order in p-azoxyanisole and its Dependence on Pressure, Volume and Temperature

Abstract: The extension of the Maier-Saupe treatment of nematic liquid crystals discussed in previous papers is able to give a quantitative description of the following properties of p-azoxyanisole: (a) the volume change at the nematic-isotropic transition point Tc , (b) the temperature variation of the long range orientational order parameter s 1 at constant pressure, (c) the temperature variation of s 1 at constant volume, (d) the volume variation of s 1 at constant temperature, and (e) the pressure invariance of s 1 at T c.

Spontaneous polarization and rotational viscosity measurements on ferroelectric liquid crystals derived from trans-p-n-alkoxycinnamic acids

Abstract: We report here the results of systematic measurements of spontaneous polarization and rotational viscosity on four structurally related homologous series derived from trans-p-n-alkoxycinnamic acids. The influence of alkyl chain length on the magnitude and temperature dependence of the polarization, and the effect of subtle structural changes on the rotational viscosity are discussed.

Observation of a smectic C*-smectic I* critical point in a binary system using polarisation measurements

Abstract: We demonstrate that in the two-phase region of a first-order smectic C*–smectic I* transition, the triangular-wave method can be used to separate out the polarisation contributions arising from the two phases. This method has been employed to trace the approach to the critical point.

Handbook of Optical Materials

Abstract: CRYSTALLINE MATERIALS Introduction Physical Properties Optical Properties Mechanical Properties Thermal Properties Magnetooptic Properties Electrooptic Properties Elastooptic Properties Nonlinear Optical Properties GLASSES Introduction Commercial Optical Glasses Specialty Optical Glasses Fused Silica Fluoride Glasses Chalcogenide Glasses Magnetooptic Properties Electrooptic Properties Elastooptic Properties Nonlinear Optical Properties Special Glasses POLYMERIC MATERIALS Optical Plastics Index of Refraction Nonlinear Optical Properties Thermal Properties Engineering Data METALS Physical Properties of Selected Metals Optical Properties Mechanical Properties Thermal Properties Mirror Substrate Materials LIQUIDS Introduction Water Physical Properties of Selected Liquids Index of Refraction Nonlinear Optical Properties Magnetooptic Properties Commercial Optical Liquids GASES Introduction Physical Properties of Selected Gases Index of Refraction Nonlinear Optical Properties Magnetooptic Properties Atomic Resonance Filters APPENDICES Safe Handling of Optical Materials Abbreviations, Acronyms, and Mineralogical or Common Names for Optical Materials Abbreviations for Methods of Preparing Optical Materials and Thin Films Fundamental Physical Constants Units and Conversion Factors

Dendron-Mediated Self-Assembly, Disassembly, and Self-Organization of Complex Systems

Abstract: Dendron-mediated self-assembly, disassembly, and self-organization of complex systems have been investigated. The most ideal building blocks would need to display shape persistence in solution and in the solid state, since only this feature provides access to the use of complementary methods of structural analysis. Most supramolecular dendrimers are chiral even when they are constructed from nonchiral building blocks and are equipped with mechanisms that amplify chirality. This poses additional challenges associated with the understanding of the structural origin of chirality in different supramolecular structures through combinations of structural analysis methods. While many supramolecular structures assembled from dendrimers and dendrons resemble some of the related morphologies generated from block-copolymers, they are much more complex and are not determined by the volume ratio between the dissimilar parts of the molecule.

Discotic Liquid Crystals: From Tailor-Made Synthesis to Plastic Electronics

Abstract: Most associate liquid crystals with their everyday use in laptop computers, mobile phones, digital cameras, and other electronic devices. However, in contrast to their rodlike (calamitic) counterparts, first described in 1907 by Vorlander, disklike (discotic, columnar) liquid crystals, which were discovered in 1977 by Chandrasekhar et al., offer further applications as a result of their orientation in the columnar mesophase, making them ideal candidates for molecular wires in various optical and electronic devices such as photocopiers, laser printers, photovoltaic cells, light-emitting diodes, field-effect transistors, and holographic data storage. Beginning with an overview of the various mesophases and characterization methods, this Review will focus on the major classes of columnar mesogens rather than presenting a library of columnar liquid crystals. Emphasis will be given to efficient synthetic procedures, and relevant mesomorphic and physical properties. Finally, some applications and perspectives in materials science and molecular electronics will be discussed.