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Ultraviolet Raman spectroscopy of graphene and transition‐metal dichalcogenides
Author(s) -
Saito Riichiro,
Nugraha Ahmad R. T.,
Hasdeo Eddwi H.,
Siregar Syahril,
Guo Huaihong,
Yang Teng
Publication year - 2015
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.201552201
Subject(s) - graphene , raman spectroscopy , ultraviolet , transition metal , spectroscopy , materials science , ultraviolet visible spectroscopy , nanotechnology , chemistry , physics , optoelectronics , optics , quantum mechanics , catalysis , biochemistry
Here, we overview Raman spectroscopy of graphene and transition‐metal dichalcogenides as a function of laser excitation energy E L , especially in the ultraviolet (UV) region. The double resonance G′ (or 2D) band of graphene is calculated for the laser energy range up to 7 eV. The intensity of the G′ band is proportional to E L − 1for E L ≤ 5 eV. We also discuss electronic Raman spectra and the asymmetric Breit–Wigner–Fano lineshape of the G band in graphene for UV light. Finally, transition‐metal dichalcogenide materials show a strong optical absorption of the UV light at the M point at which we expect a two‐dimensional van Hove singularity of density of states. The double‐resonance Raman spectra for the UV light can be assigned to a combination or overtone phonons at the M point. Equi‐energy contour of initial (blue line) and intermediate (red line) states in a double‐resonance Raman process for (a) E L = 3.49 eV and (b) E L = 6.00 eV. In the case of E L = 6.00 eV, the blue and red lines are almost overlapped on each other. Gray‐shaded areas are possible phonon wave vectors for the double‐resonant Raman process that are measured from the center of the Brillouin zone.