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Mildred S. Dresselhaus - One of the best experts on this subject based on the ideXlab platform.
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fermi energy dependence of first and second order Raman Spectra in graphene kohn anomaly and quantum interference effect
Physical Review B, 2016Co-Authors: Eddwi H Hasdeo, Ahmad R T Nugraha, Mildred S. Dresselhaus, Riichiro SaitoAbstract:Intensities of the first- and the second-order Raman Spectra are calculated as a function of the Fermi energy. We show that the Kohn anomaly effect, i.e., phonon frequency renormalization, in the first-order Raman Spectra originates from the phonon renormalization by the interband electron-hole excitation, whereas in the second-order Raman Spectra, a competition between the interband and intraband electron-hole excitations takes place. By this calculation, we confirm the presence of different dispersive behaviors of the Raman peak frequency as a function of the Fermi energy for the first- and the second-order Raman Spectra, as observed in some previous experiments. Moreover, the calculated results of the Raman intensity sensitively depend on the Fermi energy for both the first- and the second-order Raman Spectra, indicating the presence of the quantum interference effect. The electron-phonon matrix element plays an important role in the intensity increase (decrease) of the combination (overtone) phonon modes as a function of the Fermi energy.
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Raman Spectra of out of plane phonons in bilayer graphene
Physical Review B, 2011Co-Authors: Kentaro Sato, Jin Sung Park, Riichiro Saito, Chunxiao Cong, Chun Hung Lui, Tony F Heinz, G Dresselhaus, Mildred S. DresselhausAbstract:The double resonance Raman Spectra of the overtone of the out-of-plane tangential optical (oTO) phonon and of combinations of the LO, ZO, and ZA phonons with one another are calculated for bilayer graphene. In the case of the bilayer graphene, these Raman peaks are observed in the energy region between $1600$ and $1800$ cm${}^{\ensuremath{-}1}$. We obtain results for both the fixed $q=0$ and the dispersive $q=2k$ peaks of the overtones of the oTO phonon of bilayer graphene. We calculate the double resonance Raman Spectra of the combination modes coming from the LO, iTO, LA, and iTA phonons in bilayer graphene. The calculated Raman peaks are compared with the experimental results.
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fermi energy dependence of the g band resonance Raman Spectra of single wall carbon nanotubes
Physical Review B, 2009Co-Authors: Jin Sung Park, Wataru Izumida, Hootan Farhat, Martin Kalbac, Kenichi Sasaki, Riichiro Saito, Gene Dresselhaus, Mildred S. DresselhausAbstract:The Fermi energy dependence of the $G$-band resonance Raman Spectra of single-wall carbon nanotubes (SWNTs) is calculated, including the Kohn anomaly effect for metallic tubes. The gate voltage dependence of the $G$-band Raman Spectra for SWNTs shows chirality-dependent ${G}^{+}/{G}^{\ensuremath{-}}$ Spectra, reflecting their dependence on the eigenvector direction of the optical (LO and TO) phonon modes and the nanotube chirality.
Sergei V Koniakhin - One of the best experts on this subject based on the ideXlab platform.
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Raman Spectra of nonpolar crystalline nanoparticles elasticity theory like approach for optical phonons
Journal of Physical Chemistry C, 2018Co-Authors: Sergei V Koniakhin, O I Utesov, Andrey G YashenkinAbstract:A simple way to investigate theoretically the Raman Spectra (RS) of nonpolar nanoparticles is proposed. For this aim, we substitute the original lattice optical phonon eigenproblem by the continuou...
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Raman Spectra of crystalline nanoparticles replacement for the phonon confinement model
Journal of Physical Chemistry C, 2018Co-Authors: Sergei V Koniakhin, O I Utesov, Ivan Terterov, Alexandra Siklitskaya, Andrey G Yashenkin, D D SolnyshkovAbstract:In crystalline nanoparticles, the Raman peak is downshifted with respect to the bulk material and has asymmetric broadening. These effects are straightly related to the finite size of nanoparticles, giving the perspective to use Raman spectroscopy as the size probe. By combining the dynamical matrix method (DMM) and the bond polarization model (BPM), we develop a new (DMM–BPM) approach for the description of Raman Spectra of nanoparticle powders. The numerical variant of this approach is suitable for the description of small particles, whereas its analytical version is simpler to implement and allows one to obtain the Raman Spectra of arbitrary-sized particles. Focusing on nanodiamond powders, the DMM–BPM theory is shown to fit the most recent experimental data much better than the commonly used phonon confinement model.
Riichiro Saito - One of the best experts on this subject based on the ideXlab platform.
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fermi energy dependence of first and second order Raman Spectra in graphene kohn anomaly and quantum interference effect
Physical Review B, 2016Co-Authors: Eddwi H Hasdeo, Ahmad R T Nugraha, Mildred S. Dresselhaus, Riichiro SaitoAbstract:Intensities of the first- and the second-order Raman Spectra are calculated as a function of the Fermi energy. We show that the Kohn anomaly effect, i.e., phonon frequency renormalization, in the first-order Raman Spectra originates from the phonon renormalization by the interband electron-hole excitation, whereas in the second-order Raman Spectra, a competition between the interband and intraband electron-hole excitations takes place. By this calculation, we confirm the presence of different dispersive behaviors of the Raman peak frequency as a function of the Fermi energy for the first- and the second-order Raman Spectra, as observed in some previous experiments. Moreover, the calculated results of the Raman intensity sensitively depend on the Fermi energy for both the first- and the second-order Raman Spectra, indicating the presence of the quantum interference effect. The electron-phonon matrix element plays an important role in the intensity increase (decrease) of the combination (overtone) phonon modes as a function of the Fermi energy.
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Raman Spectra of out of plane phonons in bilayer graphene
Physical Review B, 2011Co-Authors: Kentaro Sato, Jin Sung Park, Riichiro Saito, Chunxiao Cong, Chun Hung Lui, Tony F Heinz, G Dresselhaus, Mildred S. DresselhausAbstract:The double resonance Raman Spectra of the overtone of the out-of-plane tangential optical (oTO) phonon and of combinations of the LO, ZO, and ZA phonons with one another are calculated for bilayer graphene. In the case of the bilayer graphene, these Raman peaks are observed in the energy region between $1600$ and $1800$ cm${}^{\ensuremath{-}1}$. We obtain results for both the fixed $q=0$ and the dispersive $q=2k$ peaks of the overtones of the oTO phonon of bilayer graphene. We calculate the double resonance Raman Spectra of the combination modes coming from the LO, iTO, LA, and iTA phonons in bilayer graphene. The calculated Raman peaks are compared with the experimental results.
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fermi energy dependence of the g band resonance Raman Spectra of single wall carbon nanotubes
Physical Review B, 2009Co-Authors: Jin Sung Park, Wataru Izumida, Hootan Farhat, Martin Kalbac, Kenichi Sasaki, Riichiro Saito, Gene Dresselhaus, Mildred S. DresselhausAbstract:The Fermi energy dependence of the $G$-band resonance Raman Spectra of single-wall carbon nanotubes (SWNTs) is calculated, including the Kohn anomaly effect for metallic tubes. The gate voltage dependence of the $G$-band Raman Spectra for SWNTs shows chirality-dependent ${G}^{+}/{G}^{\ensuremath{-}}$ Spectra, reflecting their dependence on the eigenvector direction of the optical (LO and TO) phonon modes and the nanotube chirality.
Jin Sung Park - One of the best experts on this subject based on the ideXlab platform.
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Raman Spectra of out of plane phonons in bilayer graphene
Physical Review B, 2011Co-Authors: Kentaro Sato, Jin Sung Park, Riichiro Saito, Chunxiao Cong, Chun Hung Lui, Tony F Heinz, G Dresselhaus, Mildred S. DresselhausAbstract:The double resonance Raman Spectra of the overtone of the out-of-plane tangential optical (oTO) phonon and of combinations of the LO, ZO, and ZA phonons with one another are calculated for bilayer graphene. In the case of the bilayer graphene, these Raman peaks are observed in the energy region between $1600$ and $1800$ cm${}^{\ensuremath{-}1}$. We obtain results for both the fixed $q=0$ and the dispersive $q=2k$ peaks of the overtones of the oTO phonon of bilayer graphene. We calculate the double resonance Raman Spectra of the combination modes coming from the LO, iTO, LA, and iTA phonons in bilayer graphene. The calculated Raman peaks are compared with the experimental results.
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fermi energy dependence of the g band resonance Raman Spectra of single wall carbon nanotubes
Physical Review B, 2009Co-Authors: Jin Sung Park, Wataru Izumida, Hootan Farhat, Martin Kalbac, Kenichi Sasaki, Riichiro Saito, Gene Dresselhaus, Mildred S. DresselhausAbstract:The Fermi energy dependence of the $G$-band resonance Raman Spectra of single-wall carbon nanotubes (SWNTs) is calculated, including the Kohn anomaly effect for metallic tubes. The gate voltage dependence of the $G$-band Raman Spectra for SWNTs shows chirality-dependent ${G}^{+}/{G}^{\ensuremath{-}}$ Spectra, reflecting their dependence on the eigenvector direction of the optical (LO and TO) phonon modes and the nanotube chirality.
O I Utesov - One of the best experts on this subject based on the ideXlab platform.
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Raman Spectra of nonpolar crystalline nanoparticles elasticity theory like approach for optical phonons
Journal of Physical Chemistry C, 2018Co-Authors: Sergei V Koniakhin, O I Utesov, Andrey G YashenkinAbstract:A simple way to investigate theoretically the Raman Spectra (RS) of nonpolar nanoparticles is proposed. For this aim, we substitute the original lattice optical phonon eigenproblem by the continuou...
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Raman Spectra of crystalline nanoparticles replacement for the phonon confinement model
Journal of Physical Chemistry C, 2018Co-Authors: Sergei V Koniakhin, O I Utesov, Ivan Terterov, Alexandra Siklitskaya, Andrey G Yashenkin, D D SolnyshkovAbstract:In crystalline nanoparticles, the Raman peak is downshifted with respect to the bulk material and has asymmetric broadening. These effects are straightly related to the finite size of nanoparticles, giving the perspective to use Raman spectroscopy as the size probe. By combining the dynamical matrix method (DMM) and the bond polarization model (BPM), we develop a new (DMM–BPM) approach for the description of Raman Spectra of nanoparticle powders. The numerical variant of this approach is suitable for the description of small particles, whereas its analytical version is simpler to implement and allows one to obtain the Raman Spectra of arbitrary-sized particles. Focusing on nanodiamond powders, the DMM–BPM theory is shown to fit the most recent experimental data much better than the commonly used phonon confinement model.