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Chenglin Sun - One of the best experts on this subject based on the ideXlab platform.

  • study the effect of li on the ν2 ν3 ν4 Fermi Resonance of acetonitrile by raman spectroscopy
    Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2019
    Co-Authors: Naicui Zhai, Mingzhe Zhang, Chenglin Sun
    Abstract:

    Abstract Raman spectra of the solution of LiClO4 in acetonitrile (CH3CN) at different concentrations have been measured. With increasing the concentration of Li+, it was noted that several vibrational modes of CH3CN had significant changes in Raman shifts and some new Raman peaks emerged due to the CH3CN⋯Li+ complex formation. In addition, Fermi Resonance phenomenon between the ν2' and (ν3 + ν4)' Raman bands of CH3CN⋯Li+ complex was observed. Based on the Bertran's equations, Fermi Resonance parameters of free CH3CN and CH3CN⋯Li+ complex at different concentrations have been calculated, respectively. Compared the Fermi Resonance coupling coefficients W of free CH3CN with CH3CN⋯Li+ complex at different concentrations, the free CH3CN had a little smaller value, which indicated that the ν2'/(ν3 + ν4)' Fermi Resonance in CH3CN⋯Li+ complex was much stronger than the ν2/ν3 + ν4 Fermi Resonance in CH3CN. From the detailed analysis of the effect of Li+ on the spectral features of CH3CN, the effect mechanism of Li+ coordination to CH3CN at the nitrogen of the CN group on the ν2/ν3 + ν4 Fermi Resonance of CH3CN has been elucidated.

  • Raman spectroscopic study of nonlinear modulation on Fermi Resonance of acetonitrile by hydrogen-bonding network
    Journal of Molecular Liquids, 2019
    Co-Authors: Xianwen Cao, Chenglin Sun, Hongliang Zhao, Nan Gong, Zhiwei Men
    Abstract:

    Abstract Raman spectra of acetonitrile-water mixtures are measured in different acetonitrile concentration fractions. The nitrile stretch (v2) and the combination (v3 + v4) modes are coupled by Fermi Resonance. We extract the Fermi Resonance parameters and find that the frequency separation shows non-linear dependence as a function of acetonitrile concentration fractions. v2 ~ v3 + v4 Fermi doublets intensity ratio exhibits nonlinearity, which is accelerated with the decreasing of the Fermi coupling strength. The OH stretching region is also investigated in order to reveal the variation of the water structure. Our data show that there are strong relationships between the intensity of ~3225 cm−1 band and the v2~v3 + v4 Fermi Resonance. Because the nitrile stretch and Fermi Resonance are very environmental sensitive, the nonlinear modulation on Fermi Resonance and the non-regular intensity ratio are attributed to the change of water hydrogen-bonding network. The results provide useful structural and spectral insights for the design of new experiments and the molecular structure modeling.

  • Study the effect of Li+ on the ν2/ν3+ν4 Fermi Resonance of acetonitrile by Raman Spectroscopy.
    Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2018
    Co-Authors: Naicui Zhai, Mingzhe Zhang, Chenglin Sun
    Abstract:

    Abstract Raman spectra of the solution of LiClO4 in acetonitrile (CH3CN) at different concentrations have been measured. With increasing the concentration of Li+, it was noted that several vibrational modes of CH3CN had significant changes in Raman shifts and some new Raman peaks emerged due to the CH3CN⋯Li+ complex formation. In addition, Fermi Resonance phenomenon between the ν2' and (ν3 + ν4)' Raman bands of CH3CN⋯Li+ complex was observed. Based on the Bertran's equations, Fermi Resonance parameters of free CH3CN and CH3CN⋯Li+ complex at different concentrations have been calculated, respectively. Compared the Fermi Resonance coupling coefficients W of free CH3CN with CH3CN⋯Li+ complex at different concentrations, the free CH3CN had a little smaller value, which indicated that the ν2'/(ν3 + ν4)' Fermi Resonance in CH3CN⋯Li+ complex was much stronger than the ν2/ν3 + ν4 Fermi Resonance in CH3CN. From the detailed analysis of the effect of Li+ on the spectral features of CH3CN, the effect mechanism of Li+ coordination to CH3CN at the nitrogen of the CN group on the ν2/ν3 + ν4 Fermi Resonance of CH3CN has been elucidated.

  • Pressure‐induced Fermi Resonance between fundamental modes in 7,7,8,8‐tetracyanoquinodimethane
    Journal of Raman Spectroscopy, 2017
    Co-Authors: Chenglin Sun, Hongliang Zhao, Chunyu Liu, Mi Zhou
    Abstract:

    Herein, in-situ high pressure Raman spectra of 7,7,8,8-tetracyanoquinodimethane (TCNQ) have been measured up to 10 GPa, and a first-order phase transition was detected at about 2.3 GPa. An anharmonic coupling (Fermi Resonance) between fundamental modes was observed. The relationship of Fermi Resonance parameters (intensity ratio, coupling coefficient, frequency separation and frequency separation of unperturbed transition) with pressure was discussed. The frequency separation dominated the decay of the intensity ratio of Fermi Resonance doublets, and this would be another character of anharmonic coupling between fundamental modes. Copyright © 2017 John Wiley & Sons, Ltd.

  • Double Fermi Resonance: High pressure Raman investigations on hexachloroethane
    Vibrational Spectroscopy, 2017
    Co-Authors: Hongliang Zhao, Chenglin Sun, Yu Guo, Shengnan Sun, Mi Zhou
    Abstract:

    Abstract Traditional Fermi Resonance is a vibrational mixing between a fundamental and a combinational or overtone mode. What will happen when the Resonance occurs between a generated fundamental and an overtone mode? In this report, we performed a high pressure Raman spectroscopic investigation on hexachloroethane up to 20 GPa. The origin of the triple bands at 841, 851 and 860 cm −1 were thoroughly discussed, and their intensity evolution in the compression process are further analyzed. The triple bands can be attributed to the quantum mixing between generated v 7 fundamental mode and the v 2 overtone mode, This intriguing spectral phenomenon is named as double Fermi Resonance, and a new mechanism of the interaction of double Fermi Resonance is proposed. Pressure provides us a new strategy not only for the mode assignments but also to understand the mechanism underlying the vibrational mixing.

Mi Zhou - One of the best experts on this subject based on the ideXlab platform.

  • Pressure‐induced Fermi Resonance between fundamental modes in 7,7,8,8‐tetracyanoquinodimethane
    Journal of Raman Spectroscopy, 2017
    Co-Authors: Chenglin Sun, Hongliang Zhao, Chunyu Liu, Mi Zhou
    Abstract:

    Herein, in-situ high pressure Raman spectra of 7,7,8,8-tetracyanoquinodimethane (TCNQ) have been measured up to 10 GPa, and a first-order phase transition was detected at about 2.3 GPa. An anharmonic coupling (Fermi Resonance) between fundamental modes was observed. The relationship of Fermi Resonance parameters (intensity ratio, coupling coefficient, frequency separation and frequency separation of unperturbed transition) with pressure was discussed. The frequency separation dominated the decay of the intensity ratio of Fermi Resonance doublets, and this would be another character of anharmonic coupling between fundamental modes. Copyright © 2017 John Wiley & Sons, Ltd.

  • Double Fermi Resonance: High pressure Raman investigations on hexachloroethane
    Vibrational Spectroscopy, 2017
    Co-Authors: Hongliang Zhao, Chenglin Sun, Yu Guo, Shengnan Sun, Mi Zhou
    Abstract:

    Abstract Traditional Fermi Resonance is a vibrational mixing between a fundamental and a combinational or overtone mode. What will happen when the Resonance occurs between a generated fundamental and an overtone mode? In this report, we performed a high pressure Raman spectroscopic investigation on hexachloroethane up to 20 GPa. The origin of the triple bands at 841, 851 and 860 cm −1 were thoroughly discussed, and their intensity evolution in the compression process are further analyzed. The triple bands can be attributed to the quantum mixing between generated v 7 fundamental mode and the v 2 overtone mode, This intriguing spectral phenomenon is named as double Fermi Resonance, and a new mechanism of the interaction of double Fermi Resonance is proposed. Pressure provides us a new strategy not only for the mode assignments but also to understand the mechanism underlying the vibrational mixing.

  • effect on Fermi Resonance by some external fields investigation of Fermi Resonance according to raman spectra
    Spectroscopy and Spectral Analysis, 2015
    Co-Authors: Xiulan Jiang, Chenglin Sun, Mi Zhou, Zhiwei Men, Shuqin Gao
    Abstract:

    Fermi Resonance is a phenomenon of molecular vibrational coupling and energy transfer occurred between different groups of a single molecule or neighboring molecules. Many properties of Fermi Resonance under different external fields, the investigation method of Raman spectroscopy as well as the application of Fermi Resonance, etc need to be developed and extended further. In this article the research results and development about Fermi Resonance obtained by Raman spectral technique were introduced systematically according to our work and the results by other researchers. Especially, the results of the behaviors of intramolecular and intermolecular Fermi Resonance of some molecules under some external fields such as molecular field, pressure field and temperature field, etc were investigated and demonstrated in detail according to the Raman spectra obtained by high pressure DAC technique, temperature variation technique as well as the methods we planed originally in our group such as solution concentration variation method and LCOF Resonance Raman spectroscopic technique, and some novel properties of Fermi Resonance were found firstly. Concretely, (1) Under molecular field. a. The Raman spectra of C5H5 N in CH3 OH and H2O indicates that solvent effect can influence Fermi Resonance distinctly; b. The phenomena of the asymmetric movement of the Fermi Resonance doublets as well as the fundamental involved is tuned by the Fermi Resonance which had not been found by other methods were found firstly by our variation solution concentration method; c. The Fermi Resonance properties can be influenced distinctly by the molecular group reorganization induced by the hydrogen bond and anti-hydrogen bond in solution; d. Fermi Resonance can occurred between C7 H8 and m-C8H10, and the Fermi Resonance properties behave quite differently with the solution concentration; (2) Under pressure field. a. The spectral lines shift towards high wavenumber with increasing pressure, and frequency difference Δ varies with pressure, which induced the change of W; b. The W of νi + ν4 ν3 of CCl4 in C6H6 decreased more quickly in solution than in pure liquid with increasing pressure and the Fermi Resonance disappeared ahead of that in pure liquid, which indicates that the phenomenon of Fermi Resonance induced by pressure effect can reveal the mechanism of some solvent effects. (3) Under temperature field. a. The Fermi Resonance properties of different molecules behave quite differently with temperature. For an instance, the one of CO2 can be influenced distinctly by temperature, while the one of CS2 behaves no change with temperature. This article offers systematic theoretical and experimental support to the investigation of identification and assignment of molecular spectral line, the confirmation of molecular conformation and conformers, the effect of hydrogen bond on molecular structure and properties, etc.

  • Relationship between Fermi Resonance and Solvent Effects
    Chinese Physics Letters, 2011
    Co-Authors: Xiulan Jiang, Chenglin Sun, Mi Zhou, Guang Yang, Shuqin Gao
    Abstract:

    We theoretically and experimentally study the relationship between Fermi Resonance and solvent effects and investigate the Fermi Resonance of p-benzoquinone and cyclopentanone in different solvents and the Fermi Resonance of CS2 in C6H6 at different concentrations. Also, we investigate the Fermi Resonance of C6H6 and CCl4 in their solution at different pressures. It is found that solvent effects can be utilized to search Fermi Resonance parameters such as coupling coefficient and spectral intensity ratio, etc., on the other hand, the mechanism of solvent effects can be revealed according to Fermi Resonance at high pressure.

  • Study of Fermi Resonance by means of solution concentration variation
    Guang pu xue yu guang pu fen xi = Guang pu, 2011
    Co-Authors: Xiulan Jiang, Chenglin Sun, Mi Zhou, Guang Yang, Yuanzheng Chen, Shuqin Gao
    Abstract:

    The values of Raman scattering coefficients of some molecules in which Fermi Resonance occurs vary with solution concentration variation. We measured the Raman spectra of some solvents such as CCl4, CS2, C6H6, etc by changing the concentration of the solutions ranging from 10% to 100% in volume. As a result, the authors obtained the general law of Fermi Resonance. We found some weak Fermi Resonance phenomena as well that the two bands of Raman spectrum shift asymmetrically and that the fundamental of overtone is tuned by Fermi Resonance and moves towards the same direction with the overtone simultaneously, which is same as the results Bier K. D. obtained by means of high-pressure technique. By means of this method, the authors demonstrated the conclusion that only the fundamental in combinations which has the same symmetry as the fundamental involved in Fermi Resonance directly can its intensity variation influence the Fermi Resonance. In this article, the authors present a new method to study Fermi Resonance. This method is valuable in the identification and the assignment of spectral lines of solutions, the determination of molecular configuration of enzyme, the discrimination of isomer, as well as the influences on the molecular structures and properties caused by hydrogen bond.

Shuqin Gao - One of the best experts on this subject based on the ideXlab platform.

  • effect on Fermi Resonance by some external fields investigation of Fermi Resonance according to raman spectra
    Spectroscopy and Spectral Analysis, 2015
    Co-Authors: Xiulan Jiang, Chenglin Sun, Mi Zhou, Zhiwei Men, Shuqin Gao
    Abstract:

    Fermi Resonance is a phenomenon of molecular vibrational coupling and energy transfer occurred between different groups of a single molecule or neighboring molecules. Many properties of Fermi Resonance under different external fields, the investigation method of Raman spectroscopy as well as the application of Fermi Resonance, etc need to be developed and extended further. In this article the research results and development about Fermi Resonance obtained by Raman spectral technique were introduced systematically according to our work and the results by other researchers. Especially, the results of the behaviors of intramolecular and intermolecular Fermi Resonance of some molecules under some external fields such as molecular field, pressure field and temperature field, etc were investigated and demonstrated in detail according to the Raman spectra obtained by high pressure DAC technique, temperature variation technique as well as the methods we planed originally in our group such as solution concentration variation method and LCOF Resonance Raman spectroscopic technique, and some novel properties of Fermi Resonance were found firstly. Concretely, (1) Under molecular field. a. The Raman spectra of C5H5 N in CH3 OH and H2O indicates that solvent effect can influence Fermi Resonance distinctly; b. The phenomena of the asymmetric movement of the Fermi Resonance doublets as well as the fundamental involved is tuned by the Fermi Resonance which had not been found by other methods were found firstly by our variation solution concentration method; c. The Fermi Resonance properties can be influenced distinctly by the molecular group reorganization induced by the hydrogen bond and anti-hydrogen bond in solution; d. Fermi Resonance can occurred between C7 H8 and m-C8H10, and the Fermi Resonance properties behave quite differently with the solution concentration; (2) Under pressure field. a. The spectral lines shift towards high wavenumber with increasing pressure, and frequency difference Δ varies with pressure, which induced the change of W; b. The W of νi + ν4 ν3 of CCl4 in C6H6 decreased more quickly in solution than in pure liquid with increasing pressure and the Fermi Resonance disappeared ahead of that in pure liquid, which indicates that the phenomenon of Fermi Resonance induced by pressure effect can reveal the mechanism of some solvent effects. (3) Under temperature field. a. The Fermi Resonance properties of different molecules behave quite differently with temperature. For an instance, the one of CO2 can be influenced distinctly by temperature, while the one of CS2 behaves no change with temperature. This article offers systematic theoretical and experimental support to the investigation of identification and assignment of molecular spectral line, the confirmation of molecular conformation and conformers, the effect of hydrogen bond on molecular structure and properties, etc.

  • Relationship between Fermi Resonance and Solvent Effects
    Chinese Physics Letters, 2011
    Co-Authors: Xiulan Jiang, Chenglin Sun, Mi Zhou, Guang Yang, Shuqin Gao
    Abstract:

    We theoretically and experimentally study the relationship between Fermi Resonance and solvent effects and investigate the Fermi Resonance of p-benzoquinone and cyclopentanone in different solvents and the Fermi Resonance of CS2 in C6H6 at different concentrations. Also, we investigate the Fermi Resonance of C6H6 and CCl4 in their solution at different pressures. It is found that solvent effects can be utilized to search Fermi Resonance parameters such as coupling coefficient and spectral intensity ratio, etc., on the other hand, the mechanism of solvent effects can be revealed according to Fermi Resonance at high pressure.

  • Study of Fermi Resonance by means of solution concentration variation
    Guang pu xue yu guang pu fen xi = Guang pu, 2011
    Co-Authors: Xiulan Jiang, Chenglin Sun, Mi Zhou, Guang Yang, Yuanzheng Chen, Shuqin Gao
    Abstract:

    The values of Raman scattering coefficients of some molecules in which Fermi Resonance occurs vary with solution concentration variation. We measured the Raman spectra of some solvents such as CCl4, CS2, C6H6, etc by changing the concentration of the solutions ranging from 10% to 100% in volume. As a result, the authors obtained the general law of Fermi Resonance. We found some weak Fermi Resonance phenomena as well that the two bands of Raman spectrum shift asymmetrically and that the fundamental of overtone is tuned by Fermi Resonance and moves towards the same direction with the overtone simultaneously, which is same as the results Bier K. D. obtained by means of high-pressure technique. By means of this method, the authors demonstrated the conclusion that only the fundamental in combinations which has the same symmetry as the fundamental involved in Fermi Resonance directly can its intensity variation influence the Fermi Resonance. In this article, the authors present a new method to study Fermi Resonance. This method is valuable in the identification and the assignment of spectral lines of solutions, the determination of molecular configuration of enzyme, the discrimination of isomer, as well as the influences on the molecular structures and properties caused by hydrogen bond.

  • Analysis of Spectral Intensity of Fermi Resonance of Molecules
    Guang pu xue yu guang pu fen xi = Guang pu, 2010
    Co-Authors: Yong-heng Jiang, Shuqin Gao, Biao Cao
    Abstract:

    Raman spectra of liquid carbon disulfide (CS) and carbon tetrachloride (CCl4) were measured. And the spectral intensity was analyzed using the J. F. Bertran theory and the group theory. The rule about Fermi Resonance was obtained from the Raman spectra of carbon disulfide (CS) and carbon tetrachloride (CCL4): (1) The energy can transfer between a fundamental and an overtone frequency about Fermi Resonance; the two spectra have the same intensity. The spectral intensity of the two spectra was equal (R=1) about Fermi Resonance, when the difference between fundamental of Fermi Resonance and overtone of Fermi Resonance was very small. (2) The intensity of overtone is stronger than that of fundamental's. (3) The spectrum of Fermi Resonance was observed, but the fundamental frequency was not. This article has very good reference value for the assignments in the molecular structure and the research of contents.

  • Investigation of effect of solvents on C=O Fermi Resonance with solvent variation method
    Guang pu xue yu guang pu fen xi = Guang pu, 2009
    Co-Authors: Liu-yang Zhang, Yong-heng Jiang, Zhigang Wang, Yue-meng Wang, Shuqin Gao
    Abstract:

    Fermi Resonance is one of the general and important phenomena in vibration spectra. The method of solvent variation is one of the main methods to study Fermi Resonance. In the present paper, FTIR spectroscopy was used to study the Fermi Resonance of p-benzoquinone in thirteen solvents. The results show that there are some function relationships between the dielectric constant of solvent and the intensity ratio of Fermi Resonance. And the empirical formula was obtained by curve fitting. The equation of Kirkwood-Bauer-Magat was applied to the study of Fermi Resonance. And the authors obtained the relation between the intensity ratio R and the dielectric constant epsilon. This result is in accordance with the empirical formula. In order to confirm our result, the infrared data of R. A. Nyquist and J. K. Seehra were analyzed. These results are in accord with that of p-benzoquinone.

A. M. Kamchatnov - One of the best experts on this subject based on the ideXlab platform.

  • Threshold Behavior of Strongly Localized Nonlinear Modes in Crystals with Fermi Resonance Interaction
    Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 2001
    Co-Authors: Vladimir M. Agranovich, O. A. Dubovsky, A. M. Kamchatnov, Peter Reineker
    Abstract:

    Abstract We report the existence of strongly localized modes in thin films and crystals with Fermi Resonance interaction between vibration modes of molecules. Several families of bright and dark localized modes are investigated theoretically in two-and three-dimensional systems. Simple theoretical estimations are confirmed by numerical calculations. It is shown that in higher dimensions the solutions exist which do not have their one-dimensional analogs. The strongly localized Fermi Resonance modes demonstrate the threshold behavior in any dimension in contrast to the nonlinear lattices with cubic interaction between sites.

  • Fermi Resonance Nonlinear Waves and Solitons in Organic Superlattices
    Advanced Photonics with Second-Order Optically Nonlinear Processes, 1999
    Co-Authors: V. M. Agranovich, A. M. Kamchatnov
    Abstract:

    Fermi Resonance is a phenomenon which takes place in vibrational or electronic spectra of molecules. For example, let a molecule have two vibrational modes with frequencies ωa and ωb. If the second order Resonance condition 2ω α ≃ ω b is fulfilled, then the ħωb, transition in infrared spectrum can be split into two lines of comparable intensity and the second line cannot be explained as a result of interaction of light with the vibrational a mode because the transitions with excitation of two ħω a quanta are forbidden due to well-known n→n±1 selection rule for harmonic oscillator. E. Fermi explained [1]–[2] this experimental observation as a result of nonlinear Resonance interaction of two vibrational modes with each other. Since that time the notion of Fermi Resonance has been generalized to the processes with participation of different types of quanta (e.g., ω1+ω2≃ω3, ω1+ω2≃ω3−ω4, and so on) and to electronic types of excitations as well. Further generalizations were suggested for Fermi Resonance interactions of collective modes in molecular crystals and other macroscopic systems, so that Fermi Resonance phenomenon became a part of not only molecular physics but solid state physics also (see, e.g., review articles [3]–[5]). Recent progress in molecular beam deposition method permitted one to obtain molecular multilayer structures [6] analogous to inorganic superlattice and quantum well structures.

  • Nonlinear optical vibrations in organic superlattices with interface Fermi Resonance
    Chemical Physics, 1995
    Co-Authors: Vladimir M. Agranovich, O. A. Dubovsky, A. M. Kamchatnov
    Abstract:

    Abstract We discuss the nonlinear dynamics of organic superlattices in the case of interface Fermi Resonance, which occurs when the energy ℏ ω c of excitation on one side of each interface is approximately equal to 2ℏ ω b , where ℏ ω b is the excitation energy on the other side of the interface. We demonstrate that the Fermi Resonance interaction across each interface gives rise in the classical limit to nonlinear plane waves propagating through the superlattice. A general form of the dispersion law has been found. The peculiarities of this dispersion law are discussed in several particular cases.

  • Fermi Resonance Interface Modes: Propagation along the Interfaces
    The Journal of Physical Chemistry, 1994
    Co-Authors: V. M. Agranovich, O. A. Dubovsky, A. M. Kamchatnov
    Abstract:

    We discuss the nonlinear dynamics of an interface between two layers of organic semiconductors in the case of a Fermi Resonance which occurs when the energy ha' of excitation on one side of the interface is approximately equal to 2hob with hab being the excitation energy on the other side. We develop the theory of quantum Fermi Resonance interface modes (FRIM) propagating along the interface and demonstrate that the Fermi Resonance interaction across the interface also gives rise to classical nonlinear plane waves propagating along the interface and in some cases to 2D solitons localized at the interface.

Vladimir M. Agranovich - One of the best experts on this subject based on the ideXlab platform.

  • Threshold Behavior of Strongly Localized Nonlinear Modes in Crystals with Fermi Resonance Interaction
    Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 2001
    Co-Authors: Vladimir M. Agranovich, O. A. Dubovsky, A. M. Kamchatnov, Peter Reineker
    Abstract:

    Abstract We report the existence of strongly localized modes in thin films and crystals with Fermi Resonance interaction between vibration modes of molecules. Several families of bright and dark localized modes are investigated theoretically in two-and three-dimensional systems. Simple theoretical estimations are confirmed by numerical calculations. It is shown that in higher dimensions the solutions exist which do not have their one-dimensional analogs. The strongly localized Fermi Resonance modes demonstrate the threshold behavior in any dimension in contrast to the nonlinear lattices with cubic interaction between sites.

  • Nonlinear optical vibrations in organic superlattices with interface Fermi Resonance
    Chemical Physics, 1995
    Co-Authors: Vladimir M. Agranovich, O. A. Dubovsky, A. M. Kamchatnov
    Abstract:

    Abstract We discuss the nonlinear dynamics of organic superlattices in the case of interface Fermi Resonance, which occurs when the energy ℏ ω c of excitation on one side of each interface is approximately equal to 2ℏ ω b , where ℏ ω b is the excitation energy on the other side of the interface. We demonstrate that the Fermi Resonance interaction across each interface gives rise in the classical limit to nonlinear plane waves propagating through the superlattice. A general form of the dispersion law has been found. The peculiarities of this dispersion law are discussed in several particular cases.

  • Organic superlattices with interface Fermi Resonance: optical nonlinearity☆
    Synthetic Metals, 1994
    Co-Authors: Vladimir M. Agranovich, Peter Reineker, V.i. Yudson
    Abstract:

    Abstract A mechanism of optical nonlinearity of organic superlattices is considered which is based on the Fermi Resonance between molecular excitations of alternating layers. Using Green's function formalism we have obtained a closed equation for the energy states in the vicinity of the Fermi Resonance and found a general expression for the second-order nonlinear polarizability which determines the second-harmonic generation of light caused by the interface Fermi Resonance coupling.

  • Fermi Resonance interface modes in organic multilayer structures
    Chemical Physics Letters, 1993
    Co-Authors: Vladimir M. Agranovich, O.a. Dubovky
    Abstract:

    Abstract Due to intermolecular anharmonicity a new type of vibrational as well as electronic excitation arises in the vicinity of the interface of two organic crystals for which the condition of Fermi Resonance (2ω 1 ≈ ω 2 ) takes place, where ω 1 and ω 2 are eigenfrequencies of contacting crystals.