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Journal ArticleDOI

Molecular dynamics of some crotonates using infrared band shapes

20 Apr 1984-Chemical Physics Letters (North-Holland)-Vol. 106, Iss: 3, pp 211-217
TL;DR: In this paper, the dipole correlation function of three esters of crotonic acid has been computed from the infrared absorption bands and both short-time and long-time behaviour of the correlation functions are computed and discussed.
About: This article is published in Chemical Physics Letters.The article was published on 1984-04-20. It has received 3 citations till now. The article focuses on the topics: Correlation function (statistical mechanics) & Infrared spectroscopy correlation table.
Citations
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Journal ArticleDOI
TL;DR: Time-resolved laser-induced fluorescence is evaluated for monitoring of diphenylketyl radicals produced by photoreduction of the triplet state of benzophenone to provide information about the rate of initiation and its competition with radical recombination.
Abstract: Photolytic initiation of free radical reactions is important to many areas of technology; time-resolved monitoring of submicromolar concentrations of radicals produced during the course of these reactions is needed to provide information about the rate of initiation and its competition with radical recombination. In this work, time-resolved laser-induced fluorescence is evaluated for monitoring of diphenylketyl radicals produced by photoreduction of the triplet state of benzophenone. Fluorescence from the doublet−doublet transition of the radical is excited with a continuous wave laser and provides a sensitive method to detect these intermediates at nanomolar concentrations and to study their kinetics in solution on time scales from a few microseconds to hundreds of milliseconds. The ketyl radical fluorescence measurements of radical initiation reactions allowed the H atom abstraction rate constant by triplet benzophenone from both 2-propanol and benzhydrol to be determined, where kH = (2.1 ± 0.1) × 106 M...

11 citations

Journal ArticleDOI
TL;DR: In this article, a study on how inertial rotation affects the rate of a bimolecular diffusion-controlled stereospecific reaction in solution has been made, where the orientation motion is considered as rotation with angular momentum relaxing by the strong collision mechanism (Jordan J diffusion).
Abstract: A study has been made on how inertial rotation affects the rate of a bimolecular diffusion-controlled stereospecific reaction in solution. The rate constants have been calculated in the kinematic approximation for a reaction between anisotropic and isotropic partners. The orientation motion is considered as rotation with angular momentum relaxing by the strong-collision mechanism (Jordan J diffusion). The averaging in the reaction anisotropy due to the rotation has been calculated for diffusion-type and jump-type translational mobility.
Journal ArticleDOI
TL;DR: In this article, the effect of orientational relaxation on the optical polarization of spin of electrons in high magnetic fields is analyzed in terms of the magnetoresonance parameters of triplet molecules and of orientation correlation functions, and the effect over a wide range of gas density and to formulate the criterion for the applicability of the previously developed theory of optical spin polarization in rare gases.
References
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Journal ArticleDOI
TL;DR: In this article, the Debye model of rotational diffusion by small angular steps is generalized to allow molecular reorientation through angular steps of arbitrarily large size, and the generalized diffusion models are found to give a rather accurate representation of molecular re-orientation in liquids and gases.
Abstract: The Debye model of rotational diffusion by small angular steps is generalized to allow molecular reorientation through angular steps of arbitrarily large size. The generalized diffusion models are found to give a rather accurate representation of molecular reorientation in liquids and gases, as observed in the infrared and Raman spectra of simple molecules. One interesting feature of both the theoretical and experimental correlation functions is that the approach to rotational equilibrium often takes the form of a damped oscillation, rather than the monotonic decay which is usually assumed.

559 citations

Journal ArticleDOI
TL;DR: In this article, the Fourier transformation of infrared and Raman band shapes reveals the meaning of the spectrum in terms of molecular rotation much more clearly than does the usual frequency shape.
Abstract: It is suggested that Fourier transformation of infrared and Raman band shapes reveals the meaning of the spectrum in terms of molecular rotation much more clearly than does the usual frequency shape. By looking at the time dependence directly, one may separately examine the molecular motion at short and long times The motion at short times may be analyzed directly in terms of the molecular dynamics, by the use of a power series in the time, whereas the behavior at long times is best examined by statistical arguments. This kind of analysis is illustrated by several examples, including the spectra of liquid CO and CH4.

504 citations

Journal ArticleDOI
TL;DR: In this paper, a simple application of Kubo's line shape theory to the domain of vibrational frequencies is presented, compared with the experiment, and used for predictions in vibrational modes where vibrational dephasing processes are predominant in determining the shape of condensed phase band contour.
Abstract: A simple application of Kubo’s line shape theory to the domain of vibrational frequencies is presented, compared with the experiment, and used for predictions. In vibrational modes where vibrational dephasing processes are predominant in determining the shape of the condensed phase band contour, the formalism shows that the vibrational correlation obeys a fast modulation mechanism (’’motional narrowing’’), e.g., in quinoline, tetravinyl tin, and isopropyl alcohol. However, even smaller molecules such as chloroform and methyl iodide show similar characteristics and only in exceptional cases (the uncoupled O–D stretch of D2O in H2O) is the modulation slow. This behavior is a consequence of the short modulation times (order of fractions of a picosecond) in the liquid which determine the phase loss of the vibrational amplitude after a brief period of a quasistatic distribution of molecular environments (’’rigid lattice’’) —times which can be approximately identified with the inverse average collision frequency. In order to compare theory and experiment quantitatively, the model requires that the vibrational second spectral moment must be measured in addition to the vibrational correlation function. Comparisons with vibrational memory functions, obtained from the correlation functions via the modified Langevin equation, corroborate the usefulness of the model.

287 citations

Book
01 Jan 1973
TL;DR: In this paper, the common group frequencies and all strong bands are included for infrared and Raman spectroscopy, and all bands, their molar absorption coefficients, and the solvents are displayed for ultraviolet Spectroscopy.
Abstract: The common group frequencies and all strong bands are included for infrared and Raman spectroscopy. All bands, their molar absorption coefficients (when available), and the solvents are displayed for ultraviolet spectroscopy. For 1 H and 13 CNMR the chemical shifts of recognizable groups, or a range for complex regions, and the solvents are listed. For mass spectra, the eight most abundant peaks, the parent peak (if not among the eight most abundant), and the relative intensities are displayed in order of decreasing intensity. In the Wiswesser Line Notation Index, the compounds have been cross-referenced by approximately 200 of the most common chemical classes and functional groups in the Chemical Structure and Substructure Index. This format allows rapid scanning of the significant structural feature in each compound. Volume I contains a composite alphabetical directory of both the IUPAC Compound and Common synonyms of the compounds. Structural diagrams and spectroscopic acids are included. -- AATA

287 citations

Journal ArticleDOI
TL;DR: In this paper, the second moment is found to have additive contributions from dynamical terms and from fluctuations in the environmental frequency shift, and the third and higher moments depend on averages of angular derivatives of the intermolecular potential energy, as well as on the rotational kinetic energy and shift fluctuation type terms found in the second moments.
Abstract: Molecular absorption and emission spectra (of a vibrational transition or of a single vibrational component of an electronic transition) are analyzed in terms of moments of their intensity distributions. The results are valid for an arbirtary intermolecular potential energy. The first‐moment formula allows one to identify, in an experimental spectrum, the shifted band origin. The second moment is found to have additive contributions from dynamical terms and from fluctuations in the environmental frequency shift. The dynamical terms depend on the average molecular rotational kinetic energy, the principal moments of inertia of the molecule, and the direction of the transition moment relative to the principal axes of inertia. In the classical limit, the average rotational kinetic energy is determined by the temperature, and the dynamical terms of the second moment are then independent of the intermolecular potential energy. If general, the measurement of a second moment gives an upper limit to the average rotational kinetic energy. If the shift fluctuation effect is small, the second moment measures the rotational kinetic energy. The third and higher moments depend on averages of angular derivatives of the intermolecular potential energy, as well as on the rotational kinetic energy and shift‐fluctuation‐type terms found in the second moment. For example, one of the contributions to the fourth moment of a linear molecule is the mean squared torque on the molecule.

130 citations