Fermi Resonance Effects in the Vibrational Spectroscopy of Methyl and Methoxy Groups

2014 ◽  
Vol 118 (47) ◽  
pp. 11272-11281 ◽  
Author(s):  
Edwin L. Sibert ◽  
Daniel P. Tabor ◽  
Nathanael M. Kidwell ◽  
Jacob C. Dean ◽  
Timothy S. Zwier
Keyword(s):  
Vibrational Spectroscopy ◽  
Fermi Resonance ◽  
Resonance Effects ◽  
Methoxy Groups

scholarly journals Facet-specific interaction between methanol and TiO2 probed by sum-frequency vibrational spectroscopy

2018 ◽  
Vol 115 (17) ◽  
pp. E3888-E3894 ◽  
Author(s):  
Deheng Yang ◽  
Yadong Li ◽  
Xinyi Liu ◽  
Yue Cao ◽  
Yi Gao ◽  
...  
Keyword(s):  
Vibrational Spectroscopy ◽  
Molecular Form ◽  
Specific Interaction ◽  
Fermi Resonance ◽  
Free Energies ◽  
Sum Frequency ◽  
Resonance Coupling ◽  
Bending Modes ◽  
Titanium Dioxides

The facet-specific interaction between molecules and crystalline catalysts, such as titanium dioxides (TiO2), has attracted much attention due to possible facet-dependent reactivity. Using surface-sensitive sum-frequency vibrational spectroscopy, we have studied how methanol interacts with different common facets of crystalline TiO2, including rutile(110), (001), (100), and anatase(101), under ambient temperature and pressure. We found that methanol adsorbs predominantly in the molecular form on all of the four surfaces, while spontaneous dissociation into methoxy occurs preferentially when these surfaces become defective. Extraction of Fermi resonance coupling between stretch and bending modes of the methyl group in analyzing adsorbed methanol spectra allows determination of the methanol adsorption isotherm. The isotherms obtained for the four surfaces are nearly the same, yielding two adsorbed Gibbs free energies associated with two different adsorption configurations singled out by ab initio calculations. They are (i) ∼−20 kJ/mol for methanol with its oxygen attached to a low-coordinated surface titanium, and (ii) ∼−5 kJ/mol for methanol hydrogen-bonded to a surface oxygen and a neighboring methanol molecule. Despite similar adsorption energetics, the Fermi resonance coupling strength for adsorbed methanol appears to depend sensitively on the surface facet and coverage.

Fermi Resonance Effects on the Vibration Modes of Hydrogen-Passivated Boron in Silicon

1989 ◽  
Vol 163 ◽  
Author(s):  
G.D. Watkins ◽  
W.B. Fowler ◽  
G.G. Deleo ◽  
M. Stavola ◽  
D.M. Kozuch ◽  
...  
Keyword(s):  
Second Harmonic ◽  
Fermi Resonance ◽  
Vibration Modes ◽  
Natural Explanation ◽  
Resonance Effects ◽  
Quantum Mechanical Treatment ◽  
Simple Quantum ◽  
Anharmonic Coupling ◽  
Quantitative Explanation ◽  
Direct Confirmation

Abstract10B - 11B isotope shifts have been reported recently for the vibrational frequencies of hydrogen (H) and its isotope deuterium (D) in the H-B complex in silicon. The D-10 B - D11 B shift was found to be anomalously large. We show that this effect finds a natural explanation in a phenomenon called “Fermi resonance”, arising from a weak anharmonic coupling between the second harmonic of the transverse B vibration and the longitudinal D vibration. We first present a simple classical explanation of the effect in terms of a “parametric oscillator”, or a child pumping a swing. We then outline a simple quantum mechanical treatment that provides a satisfactory quantitative explanation of the results. Our calculations also predict infrared absorption at the boron second harmonic frequencies. These are observed for both 10B and 11B with intensities and polarization as predicted, providing direct confirmation of the interpretation. The Pankove Si-H-B model, therefore, remains intact.

Vibrational spectroscopy of protonated amine–water clusters: tuning Fermi resonance and lighting up dark states

2020 ◽  
Vol 22 (38) ◽  
pp. 22035-22046 ◽  
Author(s):  
Chih-Kai Lin ◽  
Ryunosuke Shishido ◽  
Qian-Rui Huang ◽  
Asuka Fujii ◽  
Jer-Lai Kuo
Keyword(s):  
Vibrational Spectroscopy ◽  
Water Clusters ◽  
Fermi Resonance ◽  
Protonated Amine ◽  
Pass Through ◽  
Anharmonic Couplings

The H-bonded NH stretching fundamentals of protonated amine–water clusters pass through the “Fermi resonance window” formed by bending overtones, generating split bands due to anharmonic couplings.

scholarly journals Неэмпирический анализ изотопических сдвигов и резонансных эффектов в инфракрасном спектре высокого разрешения фреона-22 (CHF-=SUB=-2-=/SUB=-Cl), обогащенного -=SUP=-13-=/SUP=-C

2022 ◽  
Vol 130 (1) ◽  
pp. 11
Author(s):  
С.В. Краснощеков ◽  
И.К. Гайнуллин ◽  
В.Б. Лаптев ◽  
С.А. Климин
Keyword(s):  
Variational Calculation ◽  
Fermi Resonance ◽  
Coupled Clusters ◽  
Resonance Effects ◽  
Average Prediction Error ◽  
Fundamental Frequencies ◽  
Preliminary Identification ◽  
Quantum Mechanical Method ◽  
Moller Plesset ◽  
Van Vleck

The IR transmittance spectrum of an isotopic mixture of chlorodifluoromethane (CHF2Cl, Freon-22) with a 33% fraction of 13C and a natural ratio of chlorine isotopes was measured in the frequency range 1400-740 cm–1 with a resolution of 0.001 cm–1 at a temperature of 20C. An ab initio calculation of the structure and sextic potential energy surface and surfaces of the components of the dipole moment has been carried out by the the electronic quantum-mechanical method of Möller-Plesset, MP2/cc-pVTZ. Then the potential was optimized by replacing the harmonic frequencies with the frequencies calculated by the electronic method of coupled clusters, CCSD(T)/aug-cc-pVQZ. The fundamental and combination frequencies were calculated using the operator perturbation theory of Van Vleck (CVPTn) of the second and fourth order (n=2,4). Resonance effects were modeled using an additional variational calculation in the basis up to fourfold VCI excitation (4). The average prediction error for the fundamental frequencies of the 12C isotopologues was ~1.5 cm–1. The achieved accuracy made it possible to reliably predict the isotopic frequency shifts of the 13C isotopologues. It is shown that the strong Fermi resonance ν4/2ν6 dominates in the 12C isotopologues and is practically absent in 13C. The literature assumption [Spectrochim. Acta A, 44: 553] about the splitting of ν1 (CH) due to the resonance ν1/ν2+ν7+ν9 is confirmed. The coefficients of the polyadic quantum number are determined. The analysis made it possible to carry out a preliminary identification of the centers of the vibrational-rotational bands of isotopologues 13CHF235Cl и 13CHF237Cl in the spectrum of the mixture in preparation for individual analyzes of the vibrational-rotational structures of individual vibrational transitions.

Carbon-13 chemical shift assignments of chromones and isoflavones

1980 ◽  
Vol 58 (12) ◽  
pp. 1211-1219 ◽  
Author(s):  
Hem Chandra Jha ◽  
Fritz Zilliken ◽  
Eberhard Breitmaier
Keyword(s):  
Chemical Shift ◽  
Chemical Shifts ◽  
Chemical Shift Assignments ◽  
Resonance Effects ◽  
Naturally Occurring ◽  
Methoxy Groups ◽  
General Relations

Carbon-13 chemical shifts of 8 chromones and 35 isoflavones variously substituted by hydroxy-, acetoxy-, and methoxy-groups are assigned. The applicability of chemical shift increments reflecting inductive and resonance effects is discussed. Some general relations between substitution patterns and carbon shielding useful for the identification of naturally occurring isoflavones are outlined. Typical C—H couplings of chromone and phenyl carbons are analyzed for a 4′,6,7-trisubstituted derivative.

scholarly journals Fermi Resonance Effects on the ν1Raman Bands of Liquid CH2Br2and CH3Br

1984 ◽  
Vol 57 (10) ◽  
pp. 2997-2998 ◽  
Author(s):  
Kazuyoshi Fujita ◽  
Takuya Fukuda ◽  
Kohji Fukushi ◽  
Masao Kimura
Keyword(s):  
Fermi Resonance ◽  
Resonance Effects
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