117,297 research outputs found
HIGH VIBRATIONAL STATE ENERGY REDISTRIBUTION IN PARTIALLY DEUTERATED CYCLOPENTENES
No full text S. Rodin-Bercion, D. Cavagnat, L. Lespade and P. Maraval, J. Phys. Chem., 99, 3005 (1995) L. Lespade, S. Rodin-Bercion and D. Cavagnat, J. Phys. Chem., 101, 2568 (1997)Author Institution: LPCM, Universit\'{e} Bordeaux IExperimental investigations of high vibrational states in medium-size molecules show clear evidence of large intramolecular redistribution of the vibrational energy (IVR). In particular, the CH bond stretching vibration energy rapidly relaxes in combination states involving deformations of the angles adjacent to the initially excited CH . In this contribution, the overtone spectra ( to 6) of cyclopentene and cyclopentene are analyzed with a model formulated in curvilinear internal coordinates including also the coupling between the ring-puckering motion and the vibrations. In the dihydrogenated compound, the analysis of the spectra indicates a progressive localization of the CH stretching vibrations with increasing energy. At high energy (from to 6), the spectra of the two compounds evidence different IVR for CHD or groups
The first overtone of CH-stretchings in Polymethylene chains: a conformationally dependent spectrum
No full textCharacterization of Vibrational transition modes by use of normal form
No full textIn this paper we use the Birkhoff-Gustavson perturbation theory to
analyze the vibrational modes of two linearly coupled Morse oscillators in the
transition region from normal modes to local modes. Our study is based on:
truncation of the Hamiltonian written in normal mode coordinates at the 4th
order, transformation to normal form and analytical study; construction and use of
the approximate integrals of motion of the exact Hamiltonian according to
Birkhoff and Gustavson theory. By comparison with a previous analytical study,
we demonstrate that perturbation theory, based either on local or normal modes
can be used to accurately describe transition modes
Large intramolecular energy flows in Vibrational overtone spectra of cyclohexane-3,3,6,6-d4
No full textHighly excited Vibrational States of cyclic molecules investigated by I.C.L.A. Spectroscopy with photoacoutstic detection.
No full textTHE USE OF FOURIER TRANSFORM IN INTERPRETING VIBRATIONAL. SPECTRA.
No full text C. Jaff\'{e}, and P. Brumer, J. Chem. Phys., 73, 5646 (1980); E. L. Sibert III, W.P. Reinhardt, and J. T. Hynes, S. Che., Ptys., 77, 3583 (1982) G. Longhi, S. Abbate, C. Zagano, G. Botto, and L. Ricard-Lespade. Theor. Chim. Acta, 82, 321 (1992) D.W. Noid, M.L., Koszykowaky, and R.A. Marcus, J. Chem. Phys., 67, 404 (1977)Author Institution: Dipartimento di Chimica, Universit\""{a} della Basilicata.; Dipartimento di Matematica, Universit\'{a} dl Milano; Laboratoire de Spectroscopie Moleculaire, Universit\'{e} de Bordeaux IThe investigation of molecular vibrations through non-linear classical mechanics has achieved considerable success in accounting for the transition from the normal mode to the local mode regime(1). We have recently proved the existence of some peculiar type of modes, which differ from both local and normal modes, in a system of two coupled Morse oscillators (2). In this work we analyze the Fourier transform of some vibrational autocorrelation functions derived from numerical integration of the classical equations of motion(3). We applied these theoretical calculations to gain insight into the quasiperiodic vibrational motions of -type oscillators. Eventually we intend to use these results to further understand observed overtone absorption spectra of molecules containing methylenic groups
HIGH VIBRATIONAL STATES OF 1,2,3,4,4,5,5-d7 and 3,3,4,4-d4 CYCLOPENTENES.
No full text D CAVAGNAT. S BANISAED-VAHEDIE. L LESPADE, S RODIN. J.Chem.Soc.Faraday Trans. 88(13), 1845 (1992).Author Institution: Laboratoire de Spectroscopie Moleculaire et Cristalline, URA 124. 351 ers de la Lib\'{e}ration; Laboratoire de Spectroscopie Moleculaire et Cristalline, Universit\`{a} della Basilicata.The ring-puckering motion of cyclopentene is studied through the CH bond stretching overtones to 6) of the monohydrogenated and dihydrogenated . At high energies, the potential of the large amplitude motion may be divided into two parts: one part, which corresponds to the potential of the motion in its ground state and another part, due to the vibrational dissymetry of the CH bond stretchings. Because of this vibrational part. the potential wells, corresponding to the two axial and equatorial positions of the CH bonds, become deeper and deeper with increasing molecular energy. Thus, there is a relative ``localization'' of the high vibrational energy in the two potential wells, which is counterbalanced by its rapid redistribution in combination states through Fermi resonance couplings. The two phenomena are qualitatively modelled
Intractivity dye laser photoacoustic spectroscopy: measurements of the fifth overtone of cyclohexane
No full textAnalysis of the transition from Normal Modes to Local Modes in a system of two harmonically coupled Morse oscillators
No full textThe system consisting of two Morse oscillators coupled via either a
potential or a kinetic quadratic term is considered. The corresponding classical
equations of motion have been numerically integrated and the initial conditions
have been systematically analyzed in the regime of low total excitation energy of
the system. Particular attention was paid to the full characterization of an
intermediate type of motion, herein called transition mode, which appears at
total energy values in between those typical of normal modes and those where
local and normal modes coexist. A previously proposed perturbative approach
(Jaffé C, Brumer P (1980) J Chem Phys 73:5646) is reanalyzed and compared
with the results of numerical experiments, with the purpose of lending further
support to the existence of transition modes
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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