On the other hand, the layer-dependent Raman spectra on the Ag substrate exhibit a different trend, particularly for the E (i.e., E2u) mode (Figure ). As also seen in Figure , the softening of the phonon energies is more dramatic here. As the difference in lattice parameter between Ag and Au crystals is negligible in comparison to the difference between MoS2 and metals, this additional phonon softening is related to the higher affinity of Ag-S with respect to Au-S. As a result, significant intensity of the shoulder peak is visible for up to three layers. However, the electrostatic interaction-induced change in the A1 (A1g) mode is impeded by the first layer of MoS2, resulting in a nearly complete recovery of the A1 phonon modes in bilayer MoS2. This corroborates with the splitting of E mode (~ 380 cm -1 ) peaks in bilayer, where the lower energy peak is the contribution from the bottom strained monolayer attached to metal and the high energy mode is the restored phonon modes from the second layer. The Raman modes in tri and tetra-layer flakes exhibit greater suppression of the phonon softening, however, the most dramatic changes were observed between mono and bilayer. This inhomogeneous distribution of strain field perpendicular to the layer plane as shown in Figure leads to a substantial softening of the interlayer van der Waals (vdW) interactions between the layer attached with metal and the subsequent layers, which provide very high selectivity of only monolayer exfoliation, as can be seen in Figure .