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TRANSMISSION AND SCATTERING EFFECTS: DIRECT MULTIPOLE RESULTS

R. E. Raab and O. L. de Lange

in Multipole Theory in Electromagnetism: Classical, quantum, and symmetry aspects, with applications

Multipole theory is used to derive expressions for various birefringences observed in the transmission of a light wave through a crystal or gas, to which an external field may also be applied. The ... More

Multipole theory is used to derive expressions for various birefringences observed in the transmission of a light wave through a crystal or gas, to which an external field may also be applied. The Maxwell-Ampère equation is cast in multipole form and then solved in the lowest multipole order necessary to describe a particular effect. Those treated are: intrinsic Faraday rotation in ferromagnetic crystals and magnetic cubics, optical activity in a gas and crystal, linear birefringence in non-magnetic and magnetic cubic crystals, gyrotropic and Jones birefringences, the Kerr and Buckingham effects in an ideal gas. The last two effects are also analysed in terms of scattering theory. Published computer calculations of molecular multipole expressions for the Buckingham effect are quoted to show agreement with experimental results. An outline is given of the Jones calculus and the optical properties therein.Less

A Vital Matter: Light and Life

Theresa Levitt

in The Shadow of Enlightenment: Optical and Political Transparency in France 1789-1848

This chapter looks at the question of light and living bodies. Arago once again fashioned himself as a debunker, questioning the claims of the rising spiritualist movement that there exist previously ... More

This chapter looks at the question of light and living bodies. Arago once again fashioned himself as a debunker, questioning the claims of the rising spiritualist movement that there exist previously unknown forms of radiation that act on living organisms. Biot, meanwhile, strove to make exactly that point: through optical activity, the world could be divided into active (living) and inactive (non-living) matter. One could only distinguish the two by the effect they had on the plane of polarization of light. Biot's work became the basis of Pasteur's anti-materialism crusade.Less

Polymorphism and structure–property relations

Joel Bernstein

in Polymorphism in Molecular Crystals

The design of materials requires knowledge of the relationship between the structure of a substance and its properties. Polymorphic systems provide ideal, perhaps even unique, systems for studying ... More

The design of materials requires knowledge of the relationship between the structure of a substance and its properties. Polymorphic systems provide ideal, perhaps even unique, systems for studying structure-property relations since the molecular entity is a constant and differences in properties must be due to differences in structure. This chapter expands on this strategy of studying structure-property relations by investigating polymorphic systems. Systems studied may be categorized either in terms of properties due essentially to the individual molecules or in terms of bulk properties resulting from interactions between the molecules in the structure. The latter category includes electrical conductivity, magnetism, photovoltaicity and photoconductivity, nonlinear optical activity, second harmonic generation, photochromism, thermochromism, mechanochromism, and thermosalient effects. Among molecular properties considered are infrared and Raman spectra, UV/visible spectra, excimer emission, and excited state diffraction studies. Additional topics include solid state photochemical reactions, thermal reactions, and high pressure studies.Less

Anisotropy

B. D. Guenther

in Modern Optics

Optical anisotropic materials have an index of refraction that varies with the propagation direction in the material. These materials are said to be birefringent. In an anisotropic material, the two ... More

Optical anisotropic materials have an index of refraction that varies with the propagation direction in the material. These materials are said to be birefringent. In an anisotropic material, the two vectors E and D are no longer parallel to one another, requiring the use of tensors to describe birefringence. Some of the properties of tensors and a geometrical construct used to aid in the interpretation of symmetric second-rank tensors are presented. There are two descriptions of propagation in an anisotropic material, and both geometrical constructions are described. The nonzero scalar product E⋅k≠0 leads to Fresnel’s equation. Some materials will rotate the plane of polarization, and a brief discussion of what is called optical activity is given.Less

Polarizers

B. D. Guenther

in Modern Optics Simplified

Introduction to how to measure polarization and the degree of polarization, The various physical processes used to control polarization including: absorption, reflection, interference, and ... More

Introduction to how to measure polarization and the degree of polarization, The various physical processes used to control polarization including: absorption, reflection, interference, and birefringence. An explaination of the operation of a wire grid and its molecular equivalent, a polaroid plastic are given. Fresnel formula for reflection is used to calculate the Stokes component of the reflected light. A brief introduction to the concept of birefringence is given and the various designs of birefringent prism polarizers are listed with their advantanges and shortcomings. A sample design of a prism polarizer is given. Quarter wave and half wave retarders and their use are discussed. An optional section is devoted to optical activity and the use of chiral measurements in chemistry and drug manufacturing are discussed.Less

Polarization

Charles S. Adams and Ifan G. Hughes

in Optics f2f: From Fourier to Fresnel

This chapter discusses the polarization of light, including the transverse nature of the plane-wave solution; the linear and circular bases are introduced, and the propagation of polarized light in ... More

This chapter discusses the polarization of light, including the transverse nature of the plane-wave solution; the linear and circular bases are introduced, and the propagation of polarized light in media is analysed.Less

Dynamic Fields and Response Properties

Jochen Autschbach

in Quantum Theory for Chemical Applications: From Basic Concepts to Advanced Topics

It is shown how electronic transitions can be induced by the interaction with an electromagnetic wave of a suitable frequency. The rate of a transition between two electronic states induced by a ... More

It is shown how electronic transitions can be induced by the interaction with an electromagnetic wave of a suitable frequency. The rate of a transition between two electronic states induced by a time-dependent field is derived. The transition rate expression is used to calculate the absorption coefficient due to electronic transitions. The differential absorption coefficient for left and right circular polarized light is specific to chiral molecules and has different signs for a pair of enantiomers. The discussion then shifts to general functions describing the response of an atom or molecule to an external. The ideas developed thus far are then applied to the dynamic polarizability, molecular linear response functions in general, and the optical rotation. Linear response theory is set up within time-dependent molecular orbital theory. The Chapter concludes with a discussion of non-linear response properties and two-photon absorption.Less

Non-Choline-Containing Phospholipids: Diacyl-, Alkylacyl-, Alkenylacyl-Ethanolaminephosphoglycerides, Phosphatidylinositols, and Phosphatidylserine

Donald J. Hanahan

in A Guide to Phospholipid Chemistry

The diversity of phospholipids present in the mammalian cell membranes continues to titillate one’s scientific senses. In addition to the presence of at least 12 different structural types of ... More

The diversity of phospholipids present in the mammalian cell membranes continues to titillate one’s scientific senses. In addition to the presence of at least 12 different structural types of phospholipids in a cell that serve to complicate the picture, there are species within species. If one considers the diacyl, alkylacyl, and alkenylacyl variants, plus the number of different fatty acyl and fatty ether combinations, there can be several hundred different species present. Certainly progress is being made in relating certain species with a particular cellular process, and this is no doubt an exciting and important area of study. However, this is only the tip of the “cellular iceberg,” since there is little or no information on the biological role of the majority (certainly over 75%) of the phospholipids. Questions to be asked center on the need for such a spectrum of phospholipids. Are some structural components only, are some vestigial remnants, or do they play a crucial role in biological reactions yet to be discovered? There is no simple answer as yet, but this trend of thought should be kept in mind in any investigation on membrane lipid behavior. An important route to interpreting the role of various phospholipids in a biological milieu is to be certain of the chemical structure and identification of the molecules under study. So in continuation of the general format used in Chapter 4, the chemistry of the ethanolamine-, inositol-, and serine-containing phosphoglycerides will be explored at this point. A limited excursion will be made as to their participation in biological reactions. Though the above three classes of compounds share certain common structural features, there are sufficient differences to warrant separate treatment of each group of compounds. For example, the ethanolamine-containing phosphoglycerides can contain, in addition to the diacyl form, an alkylacyl and/or alkenylacyl form. Inositol-containing phosphoglycerides other than the diacyl type have not been reported, but several other phosphorylated species have been detected. The serine-containing phosphoglycerides have been found only as diacyl derivatives. Less

Inversion of Sucrose by Acid-Catalyzed Hydrolysis

Robert N. Compton and Michael A. Duncan

in Laser Experiments for Chemistry and Physics

This chapter describes a classic experiment in physical and organic chemistry: the measurement of the rate at which the optically active disaccharide sucrose molecule is converted into the ... More

This chapter describes a classic experiment in physical and organic chemistry: the measurement of the rate at which the optically active disaccharide sucrose molecule is converted into the monosaccharides fructose and glucose by acid catalyzed hydrolysis. The time dependence of the optical rotation of a sucrose solution upon adding HCl (protons) shows that the optical rotation slowly changes from +66.3o to –36.5o. The sign change is due to the fact that the optical rotation of fructose is oposite to and greater than that of glucose. The beginning of this chapter treats the subject of racemization of amino acids and suggests experiments using a microwave oven that bear on the origins of life, i.e., circularly polarized microwave radiation might produce an enantiomeric excess of amino acids from a racemic mixture.Less

Molecular Symmetry

Wai-Kee Li, Hung Kay Lee, Dennis Kee Pui Ng, Yu-San Cheung, Kendrew Kin Wah Mak, and Thomas Chung Wai Mak

in Problems in Structural Inorganic Chemistry

This chapter presents 23 problems covering the subject of molecular symmetry, along with the corresponding solutions.