The Experts below are selected from a list of 144 Experts worldwide ranked by ideXlab platform

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

  • intervalley scattering by acoustic phonons in two dimensional mos2 revealed by Double Resonance raman spectroscopy
    Nature Communications, 2017
    Co-Authors: Bruno R. Carvalho, Yuanxi Wang, Sandro Mignuzzi, Mauricio Terrones, C Fantini, Vincent H Crespi, Leandro M Malard, M A Pimenta
    Abstract:

    Double-Resonance Raman scattering is a sensitive probe to study the electron-phonon scattering pathways in crystals. For semiconducting two-dimensional transition-metal dichalcogenides, the Double-Resonance Raman process involves different valleys and phonons in the Brillouin zone, and it has not yet been fully understood. Here we present a multiple energy excitation Raman study in conjunction with density functional theory calculations that unveil the Double-Resonance Raman scattering process in monolayer and bulk MoS2. Results show that the frequency of some Raman features shifts when changing the excitation energy, and first-principle simulations confirm that such bands arise from distinct acoustic phonons, connecting different valley states. The Double-Resonance Raman process is affected by the indirect-to-direct bandgap transition, and a comparison of results in monolayer and bulk allows the assignment of each Raman feature near the M or K points of the Brillouin zone. Our work highlights the underlying physics of intervalley scattering of electrons by acoustic phonons, which is essential for valley depolarization in MoS2. Double-Resonance Raman scattering is a sensitive spectroscopic probe of the interplay between electrons and phonons in a crystal. Here, the authors unveil the signature of Double-Resonance intervalley scattering by acoustic phonons in two-dimensional MoS2, underpinning the physics of valley depolarization.

  • probing phonon dispersion relations of graphite by Double Resonance raman scattering
    Physical Review Letters, 2001
    Co-Authors: Riichiro Saito, Mildred S. Dresselhaus, Ado Jorio, A Souza G Filho, G Dresselhaus, M A Pimenta
    Abstract:

    The phonon dispersion relations of graphite can be probed over a wide range of the Brillouin zone by Double Resonance Raman spectroscopy. The Double Resonance Raman process provides us with new assignments for the dispersive and nondispersive features observed in the Raman spectra of disordered graphite and carbon nanotubes, some features having been incorrectly assigned previously, or not assigned at all.

  • probing phonon dispersion relations of graphite by Double Resonance raman scattering
    Physical Review Letters, 2001
    Co-Authors: Riichiro Saito, Mildred S. Dresselhaus, Ado Jorio, A Souza G Filho, G Dresselhaus, M A Pimenta
    Abstract:

    (Received 13 August 2001; published 20 December 2001)The phonon dispersion relations of graphite can be probed over a wide range of the Brillouin zoneby Double Resonance Raman spectroscopy. The Double Resonance Raman process provides us with newassignments for the dispersive and nondispersive features observed in the Raman spectra of disorderedgraphite and carbon nanotubes, some features having been incorrectly assigned previously, or not as-signed at all.

Riichiro Saito - One of the best experts on this subject based on the ideXlab platform.

  • Double Resonance raman spectroscopy of two dimensional materials
    2019
    Co-Authors: Riichiro Saito, Yuki Tatsumi, Teng Yang, Huaihong Guo, Shengxi Huang, Lin Zhou, Mildred S. Dresselhaus
    Abstract:

    In this chapter, we overview Double Resonance Raman spectra of two dimensional materials. Many weak Raman spectral peaks are observed in the two dimensional materials which can be attributed to second order, Double Resonance Raman spectra. It is useful for material characterization to understand not only first order Raman spectra but also second order Raman spectra since the second order Raman spectra has more information on electronic structure of the materials than the first order Raman spectra. Combined with the conventional first order Resonance Raman theory, we will explain why the Double Resonance condition can be strong in the two dimensional materials. Since the Double Resonance Raman spectra give the information of phonon with non-zero wavevectors in the Brillouin zone, both the resonant wavevector and corresponding Raman spectra can shift with changing the incident laser energy. Here we will discuss the physics of Double Resonance Raman spectra of graphene, transition metal dichalcogenides by theoretical analysis using the first principles calculation.

  • Double Resonance Raman spectroscopy of single-wall carbon nanotubes
    New Journal of Physics, 2003
    Co-Authors: Riichiro Saito, Alexander Grüneis, Ge. G. Samsonidze, Victor W. Brar, Gene Dresselhaus, Mildred S. Dresselhaus, Ado Jorio, Luiz Gustavo Cançado, Cristiano Fantini, Marcos A. Pimenta
    Abstract:

    A review of Double Resonance Raman spectroscopy is presented. Non-zone centre phonon modes in solids can be observed in the Double Resonance Raman spectra, in which weak Raman signals appear in a wide frequency region and their combination or overtone modes can be assigned. By changing the excitation laser energy, we can derive the phonon dispersion relations of a single nanotube.

  • probing phonon dispersion relations of graphite by Double Resonance raman scattering
    Physical Review Letters, 2001
    Co-Authors: Riichiro Saito, Mildred S. Dresselhaus, Ado Jorio, A Souza G Filho, G Dresselhaus, M A Pimenta
    Abstract:

    The phonon dispersion relations of graphite can be probed over a wide range of the Brillouin zone by Double Resonance Raman spectroscopy. The Double Resonance Raman process provides us with new assignments for the dispersive and nondispersive features observed in the Raman spectra of disordered graphite and carbon nanotubes, some features having been incorrectly assigned previously, or not assigned at all.

  • probing phonon dispersion relations of graphite by Double Resonance raman scattering
    Physical Review Letters, 2001
    Co-Authors: Riichiro Saito, Mildred S. Dresselhaus, Ado Jorio, A Souza G Filho, G Dresselhaus, M A Pimenta
    Abstract:

    (Received 13 August 2001; published 20 December 2001)The phonon dispersion relations of graphite can be probed over a wide range of the Brillouin zoneby Double Resonance Raman spectroscopy. The Double Resonance Raman process provides us with newassignments for the dispersive and nondispersive features observed in the Raman spectra of disorderedgraphite and carbon nanotubes, some features having been incorrectly assigned previously, or not as-signed at all.

Mildred S. Dresselhaus - One of the best experts on this subject based on the ideXlab platform.

  • Double Resonance raman spectroscopy of two dimensional materials
    2019
    Co-Authors: Riichiro Saito, Yuki Tatsumi, Teng Yang, Huaihong Guo, Shengxi Huang, Lin Zhou, Mildred S. Dresselhaus
    Abstract:

    In this chapter, we overview Double Resonance Raman spectra of two dimensional materials. Many weak Raman spectral peaks are observed in the two dimensional materials which can be attributed to second order, Double Resonance Raman spectra. It is useful for material characterization to understand not only first order Raman spectra but also second order Raman spectra since the second order Raman spectra has more information on electronic structure of the materials than the first order Raman spectra. Combined with the conventional first order Resonance Raman theory, we will explain why the Double Resonance condition can be strong in the two dimensional materials. Since the Double Resonance Raman spectra give the information of phonon with non-zero wavevectors in the Brillouin zone, both the resonant wavevector and corresponding Raman spectra can shift with changing the incident laser energy. Here we will discuss the physics of Double Resonance Raman spectra of graphene, transition metal dichalcogenides by theoretical analysis using the first principles calculation.

  • Double Resonance Raman spectroscopy of single-wall carbon nanotubes
    New Journal of Physics, 2003
    Co-Authors: Riichiro Saito, Alexander Grüneis, Ge. G. Samsonidze, Victor W. Brar, Gene Dresselhaus, Mildred S. Dresselhaus, Ado Jorio, Luiz Gustavo Cançado, Cristiano Fantini, Marcos A. Pimenta
    Abstract:

    A review of Double Resonance Raman spectroscopy is presented. Non-zone centre phonon modes in solids can be observed in the Double Resonance Raman spectra, in which weak Raman signals appear in a wide frequency region and their combination or overtone modes can be assigned. By changing the excitation laser energy, we can derive the phonon dispersion relations of a single nanotube.

  • probing phonon dispersion relations of graphite by Double Resonance raman scattering
    Physical Review Letters, 2001
    Co-Authors: Riichiro Saito, Mildred S. Dresselhaus, Ado Jorio, A Souza G Filho, G Dresselhaus, M A Pimenta
    Abstract:

    The phonon dispersion relations of graphite can be probed over a wide range of the Brillouin zone by Double Resonance Raman spectroscopy. The Double Resonance Raman process provides us with new assignments for the dispersive and nondispersive features observed in the Raman spectra of disordered graphite and carbon nanotubes, some features having been incorrectly assigned previously, or not assigned at all.

  • probing phonon dispersion relations of graphite by Double Resonance raman scattering
    Physical Review Letters, 2001
    Co-Authors: Riichiro Saito, Mildred S. Dresselhaus, Ado Jorio, A Souza G Filho, G Dresselhaus, M A Pimenta
    Abstract:

    (Received 13 August 2001; published 20 December 2001)The phonon dispersion relations of graphite can be probed over a wide range of the Brillouin zoneby Double Resonance Raman spectroscopy. The Double Resonance Raman process provides us with newassignments for the dispersive and nondispersive features observed in the Raman spectra of disorderedgraphite and carbon nanotubes, some features having been incorrectly assigned previously, or not as-signed at all.

A Souza G Filho - One of the best experts on this subject based on the ideXlab platform.

Ado Jorio - One of the best experts on this subject based on the ideXlab platform.