Lee and coworkers, 2010, considered MoS2 single and few-layer thickness samples on SiO2/Si substrate, studied by means of Raman spectroscopy. "Two Raman modes, E 1 2g and A1g, exhibited sensitive thickness dependence, with the frequency of the former decreasing and that of the latter increasing with thickness. The results provide a convenient and reliable means for determining layer thickness with atomic-level precision. The opposite direction of the frequency shifts, which cannot be explained solely by