Influence of curvature strain and Van der Waals force on the inter-layer vibration mode of WS2 nanotubes: A confocal micro-Raman spectroscopic study.
Transition-metal dichalcogenides (TMDs) nanostructures including nanotubes and monolayers have attracted great interests in materials science, chemistry to condensed matter physics. We present an interesting study of the vibration modes in multi-walled tungsten sulfide (WS2) nanotubes prepared via sulfurizing tungsten oxide (WO3) nanowires which are investigated by confocal micro-Raman spectroscopy. The inter-layer vibration mode of WS2 nanotubes, A1g, is found to be sensitive to the diameter and curvature strain, while the in-plane vibration mode, E(1)2g, is not. A1g mode frequency shows a redshift by 2.5 cm(-1) for the multi-layered nanotubes with small outer-diameters, which is an outcome of the competition between the Van der Waals force stiffening and the curvature strain softening. We also show that the Raman peak intensity ratio is significantly different between the 1-2 wall layered nanotubes and monolayer flat sheets.
Department of Physics, HKU-Shenzhen Institute of Research and Innovation (HKU-SIRI), HKU-CAS Joint Laboratory on New Materials, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
Xiao Hu
XH
Wang
Mathematics and Physics Centre, Department of Mathematical Sciences, Xi'an Jiaotong-Liverpool University, Suzhou 215123, China.|State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China.
Chang Cheng
CC
Zheng
Department of Physics, HKU-Shenzhen Institute of Research and Innovation (HKU-SIRI), HKU-CAS Joint Laboratory on New Materials, The University of Hong Kong, Pokfulam Road, Hong Kong, China.|Vacuum Interconnected Nanotech Workstation, Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215123, China.
Ji Qiang
JQ
Ning