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Stokes–anti‐Stokes contribution to double resonance Raman processes in graphene
Author(s) -
Kukucska G.,
Koltai J.,
Kürti J.
Publication year - 2014
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201451227
Subject(s) - phonon , raman spectroscopy , graphene , resonance (particle physics) , condensed matter physics , physics , coherent anti stokes raman spectroscopy , molecular physics , raman scattering , chemistry , atomic physics , quantum mechanics
The most relevant two‐phonon band in the Raman spectrum of graphene is the 2D band. In addition, there are numerous other combination bands with much smaller intensities in the observed spectra (e.g. 2 D ′ or D + D ′ ′ ). Their origin can be understood within the double resonance theory. However, calculations on single‐layer graphene found in the literature so far took into account only the Stokes processes for both electron–phonon interaction steps. This leads to the creation of two phonons, thus it gives the positive combination of the phonon frequencies in the Raman shift. Here we calculate the Raman spectra considering the Stokes–anti‐Stokes combinations as well: one phonon is created and another is annihilated. As a consequence features at the differences of the phonon frequencies show up. Tight binding calculations are carried out including the electron–photon and electron–phonon matrix elements explicitly. Phonon normal‐modes and frequencies are calculated at the level of density functional theory.