Collision- and Interaction-Induced Spectroscopy

Collision- and Interaction-Induced Spectroscopy PDF Author: G.C. Tabisz
Publisher: Springer Science & Business Media
ISBN: 9401101833
Category : Science
Languages : en
Pages : 581

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Book Description
Collision-or interaction-induced spectroscopy refers to radiative transitions, which are forbidden in free atoms or molecules, but which occur in clusters of interacting atoms or molecules. The most common phenomena are induced absorption, in the infrared region, and induced light scattering, which involves inelastic scattering of visible laser light. The particle interactions giving rise to the necessary induced dipole moments and polarizabilities are modelled at long range by multipole expansions; at short range, electron overlap and exchange mechanisms come into play. Information on atomic and molecular interactions and dynamics in dense media on a picosecond timescale may be drawn from the spectra. Collision-induced absorption in the infrared was discovered at the University of Toronto in 1949 by Crawford, Welsh and Locke who studied liquid O and N. Through the 1950s and 1960s, 2 2 experimental elucidation of the phenomenon, particularly in gases, continued and theoretical underpinnings were established. In the late 1960s, the related phenomenon of collision-induced light scattering was first observed in compressed inert gases. In 1978, an 'Enrico Fermi' Summer School was held at Varenna, Italy, under the directorship of J. Van Kranendonk. The lectures, there, reviewed activity from the previous two decades, during which the approach to the subject had not changed greatly. In 1983, a highly successful NATO Advanced Research Workshop was held at Bonas, France, under the directorship of G. Birnbaum. An important outcome of that meeting was the demonstration of the maturity and sophistication of current experimental and theoretical techniques.

Collision- and Interaction-Induced Spectroscopy

Collision- and Interaction-Induced Spectroscopy PDF Author: G.C. Tabisz
Publisher: Springer Science & Business Media
ISBN: 9401101833
Category : Science
Languages : en
Pages : 581

Get Book Here

Book Description
Collision-or interaction-induced spectroscopy refers to radiative transitions, which are forbidden in free atoms or molecules, but which occur in clusters of interacting atoms or molecules. The most common phenomena are induced absorption, in the infrared region, and induced light scattering, which involves inelastic scattering of visible laser light. The particle interactions giving rise to the necessary induced dipole moments and polarizabilities are modelled at long range by multipole expansions; at short range, electron overlap and exchange mechanisms come into play. Information on atomic and molecular interactions and dynamics in dense media on a picosecond timescale may be drawn from the spectra. Collision-induced absorption in the infrared was discovered at the University of Toronto in 1949 by Crawford, Welsh and Locke who studied liquid O and N. Through the 1950s and 1960s, 2 2 experimental elucidation of the phenomenon, particularly in gases, continued and theoretical underpinnings were established. In the late 1960s, the related phenomenon of collision-induced light scattering was first observed in compressed inert gases. In 1978, an 'Enrico Fermi' Summer School was held at Varenna, Italy, under the directorship of J. Van Kranendonk. The lectures, there, reviewed activity from the previous two decades, during which the approach to the subject had not changed greatly. In 1983, a highly successful NATO Advanced Research Workshop was held at Bonas, France, under the directorship of G. Birnbaum. An important outcome of that meeting was the demonstration of the maturity and sophistication of current experimental and theoretical techniques.

Collisional Effects on Molecular Spectra

Collisional Effects on Molecular Spectra PDF Author: Jean-Michel Hartmann
Publisher: Elsevier
ISBN: 0080569943
Category : Science
Languages : en
Pages : 429

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Book Description
Gas phase molecular spectroscopy is a powerful tool for obtaining information on the geometry and internal structure of isolated molecules as well as on the interactions that they undergo. It enables the study of fundamental parameters and processes and is also used for the sounding of gas media through optical techniques. It has been facing always renewed challenges, due to the considerable improvement of experimental techniques and the increasing demand for accuracy and scope of remote sensing applications. In practice, the radiating molecule is usually not isolated but diluted in a mixture at significant total pressure. The collisions among the molecules composing the gas can have a large influence on the spectral shape, affecting all wavelength regions through various mechanisms. These must be taken into account for the correct analysis and prediction of the resulting spectra. This book reviews our current experimental and theoretical knowledge and the practical consequences of collisional effects on molecular spectral shapes in neutral gases. General expressions are first given. They are formal of difficult use for practical calculations often but enable discussion of the approximations leading to simplified situations. The first case examined is that of isolated transitions, with the usual pressure broadening and shifting but also refined effects due to speed dependence and collision-induced velocity changes. Collisional line-mixing, which invalidates the notion of isolated transitions and has spectral consequences when lines are closely spaced, is then discussed within the impact approximation. Regions where the contributions of many distant lines overlap, such as troughs between transitions and band wings, are considered next. For a description of these far wings the finite duration of collisions and concomitant breakdown of the impact approximation must be taken into account. Finally, for long paths or elevated pressures, the dipole or polarizability induced by intermolecular interactions can make significant contributions. Specific models for the description of these collision induced absorption and light scattering processes are presented. The above mentioned topics are reviewed and discussed from a threefold point of view: the various models, the available data, and the consequences for applications including heat transfer, remote sensing and optical sounding. The extensive bibliography and discussion of some remaining problems complete the text. - State-of-the-art on the subject - A bibliography of nearly 1,000 references - Tools for practical calculations - Consequences for other scientific fields - Numerous illustrative examples - Fulfilling a need since there is no equivalent monograph on the subject

Interaction-induced Electric Properties of van der Waals Complexes

Interaction-induced Electric Properties of van der Waals Complexes PDF Author: Victor N. Cherepanov
Publisher: Springer
ISBN: 331949032X
Category : Science
Languages : en
Pages : 112

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Book Description
This brief explains the theory of the interaction-induced electrical properties of van der Waals complexes. It focuses on the interaction-induced electrical dipole moments, polarizabilities and first hyperpolarizabilities of atom-atomic, atom-molecular and molecular-molecular van der Waals complexes.

NBS Special Publication

NBS Special Publication PDF Author:
Publisher:
ISBN:
Category : Physical measurements
Languages : en
Pages : 452

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Book Description


Collision-induced Absorption in Gases

Collision-induced Absorption in Gases PDF Author: Lothar Frommhold
Publisher: Cambridge University Press
ISBN: 0521393450
Category : Science
Languages : en
Pages : 452

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Book Description
This book reviews the present knowledge of collision-induced absorption of infrared radiation in the dense, common gases. Following a brief introduction and review of essential background information, such as dipole radiation, molecular collisions and interactions, numerous experimental results for the absorption spectra of dense gases are presented. Other chapters review the causes and properties of dipole moments induced by molecular interactions, the theory of collision-induced absorption in monatomic gas mixtures and in molecular gases and mixtures. The final chapter discusses related phenomena and the important applications in astrophysics. Throughout the book, the emphasis is on the absorption by binary molecular complexes, but the onset of many-body effects, such as the ternary contributions and the intercollisional process, are also considered. The volume is meant to be a practical guide and sourcebook for the researcher interested in the spectroscopy of dense, neutral fluids. This edition includes a new appendix reviewing recent work.

Weakly Interacting Molecular Pairs: Unconventional Absorbers of Radiation in the Atmosphere

Weakly Interacting Molecular Pairs: Unconventional Absorbers of Radiation in the Atmosphere PDF Author: Claude Camy-Peyret
Publisher: Springer Science & Business Media
ISBN: 9781402015953
Category :
Languages : en
Pages : 312

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Book Description


Phenomena Induced by Intermolecular Interactions

Phenomena Induced by Intermolecular Interactions PDF Author: G. Birnbaum
Publisher: Springer Science & Business Media
ISBN: 1461325110
Category : Computers
Languages : en
Pages : 784

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Book Description
This book is concerned with recent experimental and theoretical work dealing with phenomena created by the transient dipoles and polarizabilities produced by intermolecular interactions. The for mer produce absorption from the microwave to the optical regions of the spectrum and the latter produce Rayleigh and Raman scattering; such absorption and scattering would be absent without collisions. Static properties, such as dielectric constant, refractive index, and Kerr effect, also exhibit the effects of induced dipoles and polarizabilities. The first observation of an infrared absorption spectrum pro duced by the collisions of molecules which ordinarily do not have an allowed dipole transition was reported in 1949 (Crawford, Welsh, and Locke). The first observation of depolarized Rayleigh spectra due to collisions in atomic gases appeared in 1968 (McTague and Birnbaum). However, it was not until 1977 that the first conference dealing with collision-induced phenomena was organized by J. D. Poll at the University of Guelph. This conference was mainly concerned with studies of collision-induced absorption in gases. Light scat tering received more attention at the second meeting of the colli sion-induced community in 1978, at the E. Fermi Summer School on "Intermolecular Spectroscopy and Dynamical Properties of Dense Sys tems," organized by J. Van Kranendonk. However, the emphasis was still on collision-induced absorption in compressed gases, although some work on liquids, solid H , and related subjects such as ro 2 tational relaxation was included. The third induced phenomena con ference, organized by F.

Computational Aspects of Electric Polarizability Calculations

Computational Aspects of Electric Polarizability Calculations PDF Author: George Maroulis
Publisher: IOS Press
ISBN: 9781586036430
Category : Science
Languages : en
Pages : 542

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Book Description
Covers such subjects as: Ab initio and Density functional theory calculations of electric polarizability and hyperpolarizability, intermolecular forces, aromaticity, electric properties of solvated molecules, NLO materials, Raman intensities, polarizability of metal and semiconductor clusters, relativistic effects on electric properties, and more.

Computational Chemistry: Reviews Of Current Trends, Vol. 2

Computational Chemistry: Reviews Of Current Trends, Vol. 2 PDF Author: Misako Aida
Publisher: World Scientific
ISBN: 9814498297
Category : Science
Languages : en
Pages : 304

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Book Description
The contributions collected in this volume complement volume 1 of this series, disclosing results of current developments in methodologies and applications of computational chemistry methods. The covered topics include fundamentals and applications of propagator calculations, as well as recent developments in the computationally efficient and accurate SAC-CI method, which allows calculation of various electronic states at the same time. SAC-CI studies of excited states of large molecular systems like porphyrins are reviewed, and its application to investigations of surface phenomena is discussed. The book also features a review of recent work on quantum Monte Carlo simulations.Furthermore, the book discusses the application of computational methods to biomolecules and, in particular, the application of the DFT methods to prediction of molecular structures and the IR spectrum of the DNA bases, as well as currently developed force field parameters and their application in molecular dynamics calculations of biologically important molecules. Lastly, there is a review of a quantum chemistry course which prepares students at the Department of Chemistry of ETH Zurich to perform their own ab initio studies.

Atoms, Molecules and Clusters in Electric Fields

Atoms, Molecules and Clusters in Electric Fields PDF Author: George Maroulis
Publisher: Imperial College Press
ISBN: 1860946763
Category : Technology & Engineering
Languages : en
Pages : 693

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Book Description
With the central importance of electric polarizability and hyperpolarizability for a wide spectrum of activities, this book charts the trends in the accurate theoretical determination of these properties in specialized fields. The contributions include reviews and original papers that extend from methodology to applications in specific areas of primary importance such as cluster science and organic synthesis of molecules with specific properties.