title: Surface enhanced Raman scattering of monolayer MX2 with metallic nano particles.
abstract: Monolayer transition metal dichalcogenides MX2 (M = Mo, W; X = S) exhibit remarkable electronic and optical properties, making them candidates for application within flexible nano-optoelectronics. The ability to achieve a high optical signal, while quantitatively monitoring strain in real-time is the key requirement for applications in flexible sensing and photonics devices. Surface-enhanced Raman scattering (SERS) allows us to achieve both simultaneously. However, the SERS depends crucially on the size and shape of the metallic nanoparticles (NPs), which have a large impact on its detection sensitivity. Here, we investigated the SERS of monolayer MX2, with particular attention paid to the effect of the distribution of the metallic NPs. We show that the SERS depends crucially on the distribution of the metallic NPs and also the phonon mode of the MX2. Moreover, strong coupling between MX2 and metallic NPs, through surface plasmon excitation, results in splitting of the and modes and an additional peak becomes apparent. For a WS2-Ag system the intensity of the additional peak increases exponentially with local strain, which opens another interesting window to quantitatively measure the local strain using SERS. Our experimental study may be useful for the application of monolayer MX2 in flexible nano-optoelectronics.
authors.affiliation: Elementary Educational College, Beijing key Laboratory for Nano-Photonics and Nano-Structure, Capital Normal University, Beijing 100048, P. R. China.|Key Laboratory of Cluster Science of Ministry of Education, School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China.
authors.forename: Duan
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Cluster Science of Ministry of Education, School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China.
authors.forename: Ye-Cun
authors.initials: YC
authors.lastname: Wu
authors.affiliation: Key Laboratory of Cluster Science of Ministry of Education, School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China.
authors.forename: Mei
authors.initials: M
authors.lastname: Yang
authors.affiliation: Key Laboratory of Cluster Science of Ministry of Education, School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Liu
authors.affiliation: Key Laboratory of Cluster Science of Ministry of Education, School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China.|KSU-Aramco Center, King Saud University, Riyadh 11451, Saudi Arabia.|School of Physics and CRANN, Trinity College, University of Dublin, Dublin 2, Ireland.
authors.forename: Cormac Ó
authors.initials: CÓ
authors.lastname: Coileáin
authors.affiliation: KSU-Aramco Center, King Saud University, Riyadh 11451, Saudi Arabia.
authors.forename: Mourad
authors.initials: M
authors.lastname: Abid
authors.affiliation: KSU-Aramco Center, King Saud University, Riyadh 11451, Saudi Arabia.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Abid
authors.affiliation: School of Physics and CRANN, Trinity College, University of Dublin, Dublin 2, Ireland.
authors.forename: Jing-Jing
authors.initials: JJ
authors.lastname: Wang
authors.affiliation: School of Physics and CRANN, Trinity College, University of Dublin, Dublin 2, Ireland.
authors.forename: Igor
authors.initials: I
authors.lastname: Shvets
authors.affiliation: Key Laboratory of Cluster Science of Ministry of Education, School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China.|KSU-Aramco Center, King Saud University, Riyadh 11451, Saudi Arabia.
authors.forename: Hongjun
authors.initials: H
authors.lastname: Xu
authors.affiliation: Division of Industrial Metrology, Korea Research Institute of Standards and Science, Daejeon 305-340, South Korea.
authors.forename: Byong Sun
authors.initials: BS
authors.lastname: Chun
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, P. R. China.
authors.forename: Huajun
authors.initials: H
authors.lastname: Liu
authors.affiliation: Key Laboratory of Cluster Science of Ministry of Education, School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China.
authors.forename: Han-Chun
authors.initials: HC
authors.lastname: Wu