Density functional theory based calculations and experimental analysis on a limited number of real samples are performed to study how the presence of silver intercalated in the van der Waals gap of few-layer MoS2 affects the low-frequency Raman active modes of this material. Silver is found to predominantly affect the breathing-like and shear-like vibrational modes of MoS2. These modes correspond to quasi-rigid movements of each individual layer with a restoring force (and, in turn, frequency) that is determined by modulations in the weak interlayer interactions. Noticeable red-shifts with increasing Ag concentration are found for all low-frequency modes. This finding indicates the potential for low-frequency vibrations as useful gauges for practical determination of silver concentration using low-frequency Raman spectroscopy. This work also describes a semi-classical linear chain model that allows to extrapolate results to a large number of layers. Further, first-principles calculations show how Raman spectroscopy can be used to characterize the quality of the two-dimensional interface between MoS2 and a silver substrate.
@article{arxiv.2112.12553,
title = {Low-frequency Raman signature of Ag-intercalated few-layer MoS$_2$},
author = {Natalya Sheremetyeva and Drake Niedzielski and Damien Tristant and Liangbo Liang and Lauren E. Kerstetter and Suzanne E. Mohney and Vincent Meunier},
journal= {arXiv preprint arXiv:2112.12553},
year = {2021}
}