Showing papers on "Fermi resonance published in 2000"
TL;DR: In this article, a finite difference method by means of density functional theory (DFT) with the B3LYP functional and a TZ2P atomic orbitals basis set, and compared to the field calculated by Maslen et al.
Abstract: The anharmonic force field of benzene has been calculated using a finite difference method by means of density functional theory (DFT) with the B3LYP functional and a TZ2P atomic orbitals basis set, and compared to the field calculated by Maslen et al. [J. Chem. Phys. 97, 4233 (1992)]. The vapor phase infrared (IR) spectra of benzene (natural isotopic mixture) and of 12C-benzene have been recorded from 450 to 6000 cm−1, at resolutions varying from 0.05 to 0.008 cm−1, and at various path lengths (0.18/42 m). The parallel bands ν11, ν4+ν12, ν5+ν12, ν2+ν11, and ν7+ν16, using the Wilson numbering, with their accompanying hot bands, have been analyzed and their origins determined to test our computed anharmonic force field. The Raman spectra of gas-phase benzene have been also recorded at medium resolution (∼0.7 cm−1) using an argon laser (line at 514.5 nm) with a power of 0.8 W and a multipass cell. In this work we compare the experimental and the theoretical frequencies and band profiles of the parallel ν1, ν2, 2ν16, 2ν4, and 2ν14 and of the corresponding hot bands, taking into account the l-vibrational doubling and all Fermi resonances within 100 cm−1. By comparison with experiment, the DFT B3LYP is shown to be more accurate than the self-consistent field (SCF): the fundamentals are calculated with a mean absolute error of 10.7 cm−1 and most of the spectroscopic constants are in better agreement with the experimental values.
139 citations
TL;DR: In this article, a molecular dynamics simulation of the intramolecular vibrational energy transfer in myoglobin at near zero temperature was performed, and the coupling coefficients had high correlation with how much the coupled modes geometrically overlapped with each other.
Abstract: Mode coupling in a protein molecule was studied by a molecular dynamics simulation of the intramolecular vibrational energy transfer in myoglobin at near zero temperature. It was found that the vibrational energy is transferred from a given normal mode to a very few number of selective normal modes. These modes are selected by the relation between their frequencies, like Fermi resonance, governed by the third order mode coupling term. It was also confirmed that the coupling coefficients had high correlation with how much the coupled modes geometrically overlapped with each other.
138 citations
TL;DR: In this paper, the ultrafast infrared Raman (IR-Raman) technique was used to study vibrational energy relaxation and vibrational cooling of polyatomic liquids, and the theoretical framework for these measurements, including force-force correlation function methods and perturbative techniques, was reviewed.
Abstract: Vibrational energy relaxation and vibrational cooling of polyatomic liquids were studied with the ultrafast infrared–Raman (IR–Raman) technique. In the IR–Raman technique, a type of two-dimensional vibrational spectroscopy, a vibrational transition is pumped with a mid-infrared pulse and the instantaneous populations of all Raman-active transitions are simultaneously probed via incoherent anti-Stokes Raman scattering of a time-delayed visible pulse. The theoretical framework for these measurements, including force–force correlation function methods and perturbative techniques, is reviewed. Experimental aspects of the IR–Raman technique are discussed, including laser instrumentation, experimental set-up, the nature of the pumping and probing processes, detection sensitivity and optical background, and the interpretation of results including spectroscopic artifacts. Then examples are provided from recent research by our group, focusing on timely problems such as the pseudo-vibrational cascade, the dynamics of doorway vibrations, dynamics of overtones with Fermi resonance, multiple vibrational excitations via combination band pumping and spectral evolution in associated liquids. Copyright © 2000 John Wiley & Sons, Ltd.
93 citations
TL;DR: Improved rest frequencies for the astronomical community and may also be beneficial in the improvement of global fits.
67 citations
TL;DR: The infrared (IR) and Raman spectra of 3,5-dimethylpyrazole have been recorded in the vapor, liquid (melt and solution) and solid states and two deuterated derivatives, C5H7n-ND and C5D7N-NH, were also studied in solid state and in solutions.
42 citations
TL;DR: In this article, a new mechanism for intramolecular vibrational redistribution (IVR) in CF3CHFI was reported, which couples the CH chromophore vibrations through a strong Fermi resonance to the formal CF stretching normal mode (a heavy atom frame mode) involving the trans F-atom across the CC bond.
Abstract: We report a new mechanism for intramolecular vibrational redistribution (IVR) in CF3CHFI which couples the CH chromophore vibrations through a strong Fermi resonance to the formal CF stretching normal mode (a heavy atom frame mode) involving the trans F-atom across the CC bond. The analysis is made possible by comparing spectroscopic results with extensive ab initio calculations of the vibrational fundamental and overtone spectra in the range extending to 12 000 cm−1. Potential energy and electric dipole moment hypersurfaces are calculated ab initio by second order Moller–Plesset perturbation theory (MP2) on a grid involving the CH stretching, two CH bending modes and one high frequency CF stretching normal mode. The potentials are scaled to obtain agreement between the experimental spectrum and the theoretical spectrum calculated by a discrete variable representation technique on this grid. Both spectra are then analyzed in terms of three-dimensional (3D) and four-dimensional (4D) effective vibrational H...
38 citations
TL;DR: In this paper, an ab initio quartic anharmonic force field for methanol has been calculated at the equilibrium position using the CCSD(T) method for the structure and the harmonic potential energy surface, and the MP4(SDQ), and a triple zeta basis set was employed with symmetrized curvilinear internal valence coordinates in all calculations.
Abstract: An ab initio quartic anharmonic force field for methanol has been calculated at the equilibrium position using the CCSD(T) method for the structure and the harmonic potential energy surface, and the MP4(SDQ) method for the anharmonic part of the surface. A triple zeta basis set was employed with symmetrized curvilinear internal valence coordinates in all calculations. The internal coordinate force field constants have been transformed into force constants in the dimensionless normal coordinate representation for various isotopomers. Vibrational term values for CH3OH, CH3OD, CD3OH, and CD3OD have been obtained using second order perturbation theory. Particular care has been devoted to the inclusion of Fermi resonance interactions between different vibrational states. A good accuracy has been achieved in the calculation of the fundamentals for all the isotopomers, the mean absolute error being 5.8 cm−1.
37 citations
TL;DR: In this article, the rovibrational spectra of deuterobromochlorofluoromethane (CDBrClF) were measured at intermediate (01 cm−1) and high resolution (00024 cm− 1 full bandwidth, half-maximum) by interferometric Fourier transform infrared spectroscopy in the range from the far infrared at 200 cm − 1 to the near infrared at 12 µm − 1 covering all the fundamentals and CD stretching overtones up to polyad N = 5.
Abstract: The rovibrational spectra of deuterobromochlorofluoromethane (CDBrClF) were measured at intermediate (01 cm−1) and high resolution (00024 cm−1 full bandwidth, half-maximum) by interferometric Fourier transform infrared spectroscopy in the range from the far infrared at 200 cm−1 to the near infrared (12 000 cm−1) covering all the fundamentals and CD stretching overtones up to polyad N=5 The spectra are completely analyzed in terms of their vibrational assignments to fundamentals, combinations and overtones At high excitation the analysis reveals the dominant anharmonic coupling between four high frequency vibrational modes; the CD stretching (ν1), two CD bending (ν2,ν3), and the CF stretching mode (ν4) The analysis is carried out using effective model Hamiltonians including three and four vibrational degrees of freedom We also present vibrational variational calculations on a grid in a four-dimensional normal coordinate subspace The potential energy and the dipole moment function are calculated ab i
33 citations
TL;DR: Four different redox states of the trinuclear ruthenium clusters of general formula [Ru3(μ3-O)(μ-CH3CO2)6(L)3] (L = xylyl isocyanide (1), tert-butyl isochenide (2)) were generated electrochemically in solution and studied by reflectance infrared spectroelectrochemistry.
Abstract: Four different redox states of the trinuclear ruthenium clusters of general formula [Ru3(μ3-O)(μ-CH3CO2)6(L)3] (L = xylyl isocyanide (1), tert-butyl isocyanide (2)) were generated electrochemically in solution and studied by reflectance infrared spectroelectrochemistry. The IR spectra in the ν(C⋮N) region show multiple-band structure in the RuIIIRuII2 (−1) and RuIII2RuII (0) states but a sharp single band in the RuIII3 (+1) or RuIVRuIII2 (+2) state. Density functional theory (DFT) ab initio calculations were performed for free xylyl isocyanide and tert-butyl isocyanide. The results suggest that the C⋮N−C bending mode interacts through Fermi resonance with the ν(C⋮N) fundamental for the 0 and −1 states of both 1 and 2. The extensive redox chemistry of the Ru3(μ3-O) clusters 1 and 2 offers a convenient means of effecting shifts in the energy of ν(C⋮N) bands of coordinated isocyanide ligands, in and out of Fermi resonance with the C⋮N−C bending overtone.
28 citations
TL;DR: In this paper, the C-H stretch spectrum of methoxy adsorbed on Cu(100) was measured using Fourier transform infrared spectroscopy and the Fermi resonance coupling constants in methoxy were calculated using a normal mode model where the unperturbed modes were either experimentally determined or inferred from ab initio calculations performed for a methoxy-Mo model complex.
Abstract: The C–H stretch spectrum of methoxy adsorbed on Cu(100) has been measured using Fourier transform infrared spectroscopy. Fermi resonance coupling constants in methoxy are calculated using a normal mode model where the unperturbed modes were either experimentally determined or inferred from ab initio calculations performed for a methoxy-Mo model complex. The measured frequency shifts and intensity redistribution observed in the C–H stretch region are qualitatively reproduced by the calculations.
26 citations
TL;DR: In this article, the mid-IR spectra of the I−⋅HCOOH/Arm(m=1-4) ion-acid complexes were reported.
Abstract: We report mid-IR predissociation spectra of the I−⋅HCOOH⋅Arm(m=1–4) ion-acid complexes. The spectra are consistent with a planar structure where both hydrogens are engaged in ionic H bonds. Upon binding to the ion, the OH stretching fundamental displays a much more dramatic redshift (792 cm−1) than that of the CH stretch (99 cm−1), giving rise to a complex series of bands in the 2750–2950 cm−1 region. The contributions of the CH and OH stretches to the spectrum are isolated by recording spectra of the I−⋅DCOOH and I−⋅HCOOD species, which reveal that the OH stretching vibration is accompanied by combination bands involving soft modes while the CH stretch spectrum is dominated by a single feature. Some of the complexity in the I−⋅HCOOH spectrum arises from a strong Fermi resonance interaction between the v=1 level of the OH stretch and an overtone or combination band involving CH motion. We compare this behavior to that of the previously reported I−⋅CH3OH and I−⋅H2O complexes.
TL;DR: In this paper, a full quartic potential energy surface is determined for core-ionized methane and used to investigate coupling between vibrational modes, and a strong Fermi resonance is found between the first excited state of the symmetric stretching mode ν 1′ and a doubly excited bending mode, whereas the corresponding interaction is less pronounced for v1′=2.
Abstract: A full quartic potential energy surface is determined for core-ionized methane and used to investigate coupling between vibrational modes. A strong Fermi resonance is found between the first excited state of the symmetric stretching mode ν1′ and a doubly excited bending mode, whereas the corresponding interaction is less pronounced for v1′=2. In terms of the carbon 1s photoelectron spectrum of methane, the net effect of the mode coupling is to reduce the apparent contribution from anharmonicity to peak positions. The contribution from anharmonicity to the intensity of each peak is dominated by cubic and quartic terms in the symmetric stretching coordinate, and remains significant. This resolves a paradox pointed out in a recent experimental work [Carroll et al., Phys. Rev. A 59, 3386 (1999)].
TL;DR: In this paper, an analysis of the vibrational frequencies observed with high-resolution electron energy loss spectroscopy (HREELS) and reflection adsorption infrared spectroscopic (RAIRS) for methoxy adsorbed at the threefold sites on the Cu(111) surface has been performed using ab initio cluster calculations.
Abstract: An analysis of the vibrational frequencies observed with high-resolution electron energy loss spectroscopy (HREELS) and reflection adsorption infrared spectroscopy (RAIRS) for methoxy adsorbed at the threefold sites on the Cu(111) surface has been performed using ab initio cluster calculations. The OC stretch and the CH3 bending and rock modes can readily be assigned with the computed harmonic vibrational frequencies, but the three-peak structure experimentally observed in the CH stretching region is more challenging. The frequencies of the first overtone for the CH3 bending modes are found to be very close to the fundamental CH stretching frequencies suggesting that a Fermi resonance between the two types of modes might take place. We verify this origin for the three-peak structure in the CH stretching region by using a simple numerical differentiation procedure to estimate the energy third derivatives, which should be the principal cause of the coupling between the CH stretching fundamentals and the bending overtones. Using this procedure we compute three dipole active modes in the CH stretching region with a relative intensity pattern very similar to that observed in the HREELS and RAIRS. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 77: 350–357, 2000
TL;DR: In this paper, the infrared gas-phase spectra of bromofluoromethane (CH 2 BrF) have been studied in the region below 6200 cm −1 under conditions of medium resolution.
TL;DR: In this paper, the second, third, fourth and fourth overtones of the methyl C-H stretches in CH 3CF2Cl and CH3CFCl2 were measured.
Abstract: Photoacoustic spectra of the second (3νCH), third (4νCH), and fourth (5νCH) overtones of the methyl C–H stretches in CH3CF2Cl and CH3CFCl2 were measured. The spectra are characterized by a multiple peak structure of partially resolved triplets and quartets with an anomalous linewidth decrease in the 4νCH region. The results are interpreted in terms of a simplified local mode model for C–H stretching vibrations, including also the stretch-deformation Fermi resonances. The model accounts for most spectral features and allows determination of the time scale for vibrational redistribution.
TL;DR: In this paper, a vibrational analysis and a study of the first low-lying electronic states of the F 2 CN radical are reported, where B3LYP and CCSD(T) wave functions are used to calculate the optimized geometry and the potential function, while the electronic vertical transitions are studied from a CASPT2 approach.
TL;DR: In this article, the relative absorption intensities of the Fermi resonance polyads of isolated CH chromophore for the CHCl3 molecule were calculated with one-dimensional and two-dimensional dipole moment surfaces, which are obtained by the ab initio density functional method.
Abstract: Relative absorption intensities of the Fermi resonance polyads of isolated CH chromophore for the CHCl3 molecule were calculated with one-dimensional and two-dimensional dipole moment surfaces, which are obtained by the ab initio density functional method. The calculation showed an unusual strong absorption at the second Fermi resonance polyad, which agrees well with the experimental data. Such an intensities anomaly can be attributed to the nonlinearity of the dipole moment surface in the vicinity of the equilibrium configuration. By taking advantage of the two-dimensional dipole moment surface where both CH stretching and bending vibrations are taken into consideration, the ν1 and 2ν4 bands which constitute the first Fermi resonance polyad and have little wave function mixture, are found to be of almost equal intensity. Such a calculation agrees with observations.
TL;DR: In this paper, the relative intensities of the Fermi resonance polyads involving CH stretching and bending vibrations for the CHI 3 molecule are calculated with one-and two-dimensional dipole moment surfaces.
TL;DR: In this article, the effects of the initial vibrational excitation of D2 and of the umbrella motion of NH3+ are studied, and the state-to-state reaction probabilities for the two isotopic variants differ qualitatively.
Abstract: The reaction between NH3+ and D2 (or H2), leading to NH3D++D (or NH4++H) is investigated using a quantum wave packet approach at a collision energy below 2.5 eV. The study is restricted to the collinear geometry preserving C3v symmetry. Three degrees of freedom are explicitly treated: the reactive D–D and N–D distances, and the umbrella angle of NH3. The effects of the initial vibrational excitation of D2 (or H2) and of the umbrella motion of NH3+ are studied. The reaction probability is found to be large and to decrease with internal excitation of the reagents. The state-to-state reaction probabilities for the two isotopic variants differ qualitatively. This is related to the existence of a Fermi resonance in the geometrically constrained NH4+ ion, which does not exist in NH3D+. The umbrella motion is found to play an active role in the reactivity at a collision energy above 1 eV.
TL;DR: In this paper, the relative absorption intensities of the Fermi resonance polyads of isolated C-H chromophore for the CHCl3 molecule are calculated by one-dimensional dipole moment surface which had been obtained by the ab initio density functional method B3PW91 with 6-311++G(3df, 2pd) basis set, and agree very well with the experimental results.
Abstract: Relative absorption intensities of the Fermi resonance polyads of isolated C-H chromophore for the CHCl3 molecule are calculated by one-dimensional dipole moment surface which had been obtained by the ab initio density functional method B3PW91 with 6-311++G(3df, 2pd) basis set, and agree very well with the experimental results. It is shown that the nonlinearity of the dipole moment surface in the vicinity of the equilibrium configuration is responsible for the intensities anomaly, i.e. the unusual strong intensities of the second Fermi resonance polyad.
TL;DR: In this paper, the Fermi resonance phenomenon in the liquid and gas phase spectra of benzoyl chloride was found to be preserved also in the adsorbed phase.
TL;DR: In this article, the authors performed semiempirical molecular orbital calculations for the totally symmetric vibrations of the C60 molecule and found that the ratio of force constants calculated for the two different types of C-C bonds in fullerene is 1.389.
Abstract: Semiempirical molecular orbital calculations are carried out for the totally symmetric vibrations of the C60 molecule. The calculated equilibrium geometry coincides with the precision experimental data to within measurement error. The ratio of force constants calculated for the two different types of C-C bonds in fullerene is equal to 1.389. A comparison of the computational results with the Raman scattering data indicates that there may be Fermi resonance between the totally symmetric vibrations.
TL;DR: In this paper, high-resolution infrared spectra of several hot band systems of NC-C C-CN involving ν 4, ν 5, ν 7 and ν 8 have been investigated.
TL;DR: In this paper, a theory is developed to describe the profiles of hydrogen stretching infrared bands of hydrogen-bonded solids taking into account the anharmonic coupling between the high-frequency stretching vibration, ν (XH), and low-frequency lattice phonons, Ω i, as well as multi-Fermi resonances between states involving the XH stretching and overtones or combinations of some internal modes.
Abstract: A theory is developed to describe the profiles of hydrogen stretching infrared bands of hydrogen-bonded solids taking into account the anharmonic coupling between the high-frequency stretching vibration, ν (XH), and low-frequency lattice phonons, Ω i , as well as multi-Fermi resonances between states involving the ν (XH) stretching and overtones or combinations of some internal modes. The theory has been constructed in the framework of the extended molecular exciton Davydov approach. Model calculations show that the strong couplings between the high frequency ν (XH) and low-lattice vibration frequencies, Ω i , generate the broadness of the ν (XH) band but the multi-Fermi resonances between the ν (XH) state and overtones or combinations of internal modes generate the complicated substructure band which is observed experimentally.
TL;DR: The most likely explanation is that a coincidence among the intensity parameters is responsible for a very low value of the dipole moment derivative; a weak Fermi resonance with the (v(6) = 2, l = 0) state may also participate in the final total wipeout of the band.
TL;DR: In this article, the low frequency vibrational spectrum of crystalline adipic acid has been investigated in the range 20 −450 cm−1 at room and low temperatures, and it is shown that the doublet and quartet structures observed for several bands are due to Davydov splitting and Fermi resonance effects.
TL;DR: In this paper, the fine structure of the vibrational absorption of N 2, 14 N N 15 N and 15 N 2 was analyzed by a Fermi resonance with the ν 3 carbon dioxide vibrational mode.
TL;DR: In this paper, it was shown that in crystals, near the Fermi resonance of optical excitons, in addition to the solitons discovered before, such as multi-exciton bound complexes of cusp-, crater-, and dark-type possessing a single carrier frequency, amplitude, and envelope, there are nonlinear soliton excitations of a crucially new, breather-type.
Abstract: It has been shown that in crystals, near the Fermi resonance of optical excitons, in addition to the solitons discovered before, such as multi-exciton bound complexes of cusp-, crater-, and dark-type possessing a single carrier frequency, amplitude, and envelope, there are nonlinear soliton excitations of a crucially new, breather-type Such periodic soliton oscillations exhibit slowly pulsing amplitudes of high-frequency oscillations, with the carrier frequency being a multiple of the frequency of pulsations In accordance with the multiplicity, the depth of pulsations defines a series of the carrier frequencies, which are condensed near the basic frequency of optical oscillations The spatial dependence of the two envelopes of new solitons of the cusp type is determined With the increase in multiplicity, the sharpness of the space envelope of a soliton decreases, while the localization radius increases Some other features of the solitons of new type are listed