title: Anomalous lattice vibrations of monolayer MoS2 probed by ultraviolet Raman scattering.
abstract: We present a comprehensive Raman scattering study of monolayer MoS2 with increasing laser excitation energies ranging from the near-infrared to the deep-ultraviolet. The Raman scattering intensities from the second-order phonon modes are revealed to be enhanced anomalously by only the ultraviolet excitation wavelength 354 nm. We demonstrate theoretically that such resonant behavior arises from a strong optical absorption that forms near the Γ point and ½ΓK of the band structure and an inter-valley resonant electronic scattering by the M-point phonons. These results advance our understanding of the double resonance Raman scattering process in low-dimensional semiconducting nanomaterials and provide a foundation for the technological development of monolayer MoS2 in the ultraviolet frequency range.
authors.affiliation: Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan. hliu@ntnu.edu.tw.
authors.forename: Hsiang-Lin
authors.initials: HL
authors.lastname: Liu
authors.forename: Huaihong
authors.initials: H
authors.lastname: Guo
authors.forename: Teng
authors.initials: T
authors.lastname: Yang
authors.forename: Zhidong
authors.initials: Z
authors.lastname: Zhang
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Kumamoto
authors.forename: Chih-Chiang
authors.initials: CC
authors.lastname: Shen
authors.forename: Yu-Te
authors.initials: YT
authors.lastname: Hsu
authors.forename: Lain-Jong
authors.initials: LJ
authors.lastname: Li
authors.forename: Riichiro
authors.initials: R
authors.lastname: Saito
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kawata