  We investigated interlayer phonon modes of mechanically exfoliated few-layer
2H-SnS2 samples by using room temperature low-frequency micro-Raman
spectroscopy. Raman measurements were performed using laser wavelength of
441.6, 514.4, 532 and 632.8 nm with power below 100 uW and inside a vacuum
chamber to avoid photo-oxidation. The intralayer Eg and A1g modes are observed
at ~206 cm-1 and ~314 cm-1, respectively, but the Eg mode is much weaker for
all excitation energies. The A1g mode exhibits strong resonant enhancement for
the 532 nm (2.33 eV) laser. In the low-frequency region, interlayer vibrational
modes of shear and breathing modes are observed. These modes show
characteristic dependence on the number of layers. The strengths of the
interlayer interactions are estimated by fitting the interlayer mode
frequencies using the linear chain model and are found to be 1.64 x10^19 N.m-3
and 5.03 x10^19 N.m-3 for the shear and breathing modes, respectively.
