Raman spectra of 2D MoS2 under the laser excitation with different wavelengths and variable polarization states

In this paper, first, we show the measuring results of 2D MoS2 Raman spectra separately under the laser excitation of 532nm, 660nm, and 785nm. We confirmed that when the photon energy is close to the energy gap of the single layer MoS2 (i.e. when using the 660nm laser wavelength), many Raman spectral peaks related to double resonance will appear. Through analysis, we actually can locate total 18 Raman spectral peaks under 660nm excitation, and we labeled the vibration origin of some Raman peaks. Then, we present the Raman spectra characteristics of 2D MoS2 excited by the laser (532nm) with different polarization, where we did the measurements with the radially polarized light and azimuthally polarized light and the corresponding radial or azimuthal polarization analyzer. We analyzed the measuring results and found that the Raman spectra contributed by two different parts: one part comes from the light that still keeps the radial or azimuthal polarization, while the other part lost the original polarization.