Electronic Absorption Spectra and Geometry of Organic Molecules


Book Description

Electronic Absorption Spectra and Geometry of Organic Molecules: An Application of Molecular Orbital Theory focuses on electronic absorption spectra of organic compounds and molecules. The book begins with the discussions on molecular spectra, electronic absorption spectra of organic compounds, and practical measures of absorption intensity. The text also focuses on molecular orbital theory and group theory. Molecular state functions; fundamental postulates of quantum theory; representation of symmetry groups; and symmetry operations and symmetry groups are described. The book also discusses shape of absorption bands and geometry of excited electronic states; effect of environment on electronic absorption spectra; and the application of simple LCAO MO method to simple p systems. An evaluation of the parameters used in simple LCAO MO method is presented. The text notes the usefulness and restrictions of simple LCAO MO method in the interpretation of electronic absorption spectra. The correlation between results of simple MO calculation and spectral data in aromatic hydrocarbons, and correlation between results of simple MO calculation and spectral data in conjugated linear polyenes are discussed. The book also looks at MO methods and the relations between electronic absorption spectra and geometry of molecules, biphenyl, styrene, and related compounds. The text is a good source of data for researchers and chemistry students who want to study electronic absorption spectra.




Photochemistry of Organic Compounds


Book Description

Photochemistry of Organic Compounds: From Concepts to Practice provides a hands-on guide demonstrating the underlying principles of photochemistry and, by reference to a range of organic reaction types, its effective use in the synthesis of new organic compounds and in various applications. The book presents a complete and methodical approach to the topic, Working from basic principles, discussing key techniques and studies of reactive intermediates, and illustrating synthetic photochemical procedures. Incorporating special topics and case studies covering various applications of photochemistry in chemistry, environmental sciences, biochemistry, physics, medicine, and industry. Providing extensive references to the original literature and to review articles. Concluding with a chapter on retrosynthetic photochemistry, listing key reactions to aid the reader in designing their own synthetic pathways. This book will be a valuable source of information and inspiration for postgraduates as well as professionals from a wide range of chemical and natural sciences.




Molecular Spectrocopy


Book Description

Designed as a textbook for undergraduate and postgraduate students of chemistry and physics, Atomic and Molecular Spectroscopy elucidates the basic principles and applications of spectroscopy. The physical and quantitative aspects of spectroscopic techniques are covered comprehensively in one book. Simple mathematical concepts are used to explain the important role that mathematics plays in the development of the subject. Elementary quantum mechanical principles are introduced to relate the characteristic chemical behaviour of atoms and molecules such as vector representation of momentum and vector coupling approximation to spectra.




The Science of Photobiology


Book Description

Although there are several excellent books covering a few of the specialized areas of photobiology, at the present time there is no book that covers all areas of the science of photobiology. This book attempts to fill this void. The science of photobiology is currently divided into 14 subspecialty areas by the American Society for Photobiology. The first 14 chapters of this book deal with those subspecialty areas, each written by a leader in the field. Chapter 15, entitled "New Topics in Photobiology," highlights areas of research that may be desig nated sUbspecialties of photobiology in the future. This book has been written as a textbook to introduce the science of photobiology to advanced undergraduate and graduate students. The chapters are written to provide a broad overview of each topic. They are designed to contain the amount of information that might be presented in a one-to two-hour general lecture. The references are not meant to be exhaustive, but key refer ences are included to give students an entry into the literature. Frequently a more recent reference that reviews the literature will be cited rather than the first paper by the author making the original discovery. Whenever practical, a classroom demonstration or simple laboratory exercise has been provided to exemplify one or more major points in a chapter.




Light Absorption of Organic Colorants


Book Description

Although studies on synthetic dyes have been performed for more than 100 years, their detailed elucidation requires further extensive research. The discovery of novel high polymers, the necessity of supplying a whole range of shades and increasing require ments for dyestuffs of high fastness properties give rise to a permanent search for new dyes. Extensive investigations on dyes were also occasioned by various applications in the field of spectral sensitization and of staining of biological specimens. Another more recent development concerns the lasing properties of some organic dyes. Most of the progress, however, was only achieved by time-consuming, purely empirical approaches and theoretical understanding of the dye properties is only at its very beginnings. The color is the sine qua non of every dye. For this reason organic chemists and color chemists have looked for relations between the "color and constitution" of dye molecules for a long time. This knowlege as a whole is known as "theory of color". The classic theory of color was established abou t 100 years ago by Witt and was signi ficantly extended 50 years later by W. Konig.







Nonbenzenoid Aromatics


Book Description

Nonbenzenoid Aromatics, Volume II, provides an overview of the state of knowledge in the field of non-benzenoid aromatic compounds. The theme that threads its way through the six chapters is that of ""aromaticity,"" with each author making an effort to evaluate this concept in light of his own work. It is with this in mind that this treatise was initiated with an historical account tracing the development of the idea up to the discovery of the electron. The book begins with discussions of the estimation of the thermochemical and kinetic stability of a system which has not yet been synthesized and the calculation of electronic spectra. This is followed by separate chapters on the electron spin resonance (ESR) spectra of radical ions of nonbenzenoid aromatics; the theoretical and empirical bases of exaltation; and treatment of cyclic (4n + 2) p-electron systems with six or more p-electrons and bearing one or more formal charges. Subsequent chapters deal with the chemical binding and delocalization in phosphonitrilic derivatives, and cyclobutadiene-metal complexes.




Molecular Design


Book Description

This book is a systematic presentation of the methods that have been developed for the interpretation of molecular modeling to the design of new chemicals. The main feature of the compilation is the co-ordination of the various scientific disciplines required for the generation of new compounds. The five chapters deal with such areas as structure and properties of organic compounds, relationships between structure and properties, and models for structure generation. The subject is covered in sufficient depth to provide readers with the necessary background to understand the modeling techniques. The book will be of value to chemists in industries involved in the manufacture of organic chemicals such as solvents refrigerants, blood substitutes, etc. It also serves as a reference work for researchers, academics, consultants, and students interested in molecular design.




Organic Solar Cells


Book Description

This book covers in a textbook-like fashion the basics or organic solar cells, addressing the limits of photovoltaic energy conversion and giving a well-illustrated introduction to molecular electronics with focus on the working principle and characterization of organic solar cells. Further chapters based on the author’s dissertation focus on the electrical processes in organic solar cells by presenting a detailed drift-diffusion approach to describe exciton separation and charge-carrier transport and extraction. The results, although elaborated on small-molecule solar cells and with focus on the zinc phthalocyanine: C60 material system, are of general nature. They propose and demonstrate experimental approaches for getting a deeper understanding of the dominating processes in amorphous thin-film based solar cells in general. The main focus is on the interpretation of the current-voltage characteristics (J-V curve). This very standard measurement technique for a solar cell reflects the electrical processes in the device. Comparing experimental to simulation data, the author discusses the reasons for S-Shaped J-V curves, the role of charge carrier mobilities and energy barriers at interfaces, the dominating recombination mechanisms, the charge carrier generation profile, and other efficiency-limiting processes in organic solar cells. The book concludes with an illustrative guideline on how to identify reasons for changes in the J-V curve. This book is a suitable introduction for students in engineering, physics, material science, and chemistry starting in the field of organic or hybrid thin-film photovoltaics. It is just as valuable for professionals and experimentalists who analyze solar cell devices.




Semiempirical Methods of Electronic Structure Calculation


Book Description

If one reflects upon the range of chemical problems accessible to the current quantum theoretical methods for calculations on the electronic structure of molecules, one is immediately struck by the rather narrow limits imposed by economic and numerical feasibility. Most of the systems with which experimental photochemists actually work are beyond the grasp of ab initio methods due to the presence of a few reasonably large aromatic ring systems. Potential energy surfaces for all but the smallest molecules are extremely expensive to produce, even over a restricted group of the possible degrees of freedom, and molecules containing the higher elements of the periodic table remain virtually untouched due to the large numbers of electrons involved. Almost the entire class of molecules of real biological interest is simply out of the question. In general, the theoretician is reduced to model systems of variable appositeness in most of these fields. The fundamental problem, from a basic computational point of view, is that large molecules require large numbers of basis functions, whether Slater type orbitals or Gaussian functions suitably contracted, to provide even a modestly accurate description of the molecular electronic environment. This leads to the necessity of dealing with very large matrices and numbers of integrals within the Hartree-Fock approximation and quickly becomes both numerically difficult and uneconomic.




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