Resonant Raman scattering at exciton states tuned by pressure and temperature in2H-MoS2

We report on the temperature and pressure dependence of Stokes and anti-Stokes Raman spectra of a single crystal of $2H{\text{-MoS}}_{2}$ as the energies of the ${A}_{1}$ and ${B}_{1}$ excitons, ${E}_{A1}$ and ${E}_{B1}$, are tuned to resonate with an exciting laser at ${E}_{L}=1.96\text{ }\text{eV}$. Pressure- and temperature-dependent intensity ratio analysis of the resonant ${A}_{1g}$ phonon and the ${E}_{2g}^{1}$ phonon is complemented by the calculation of resonance Raman probability profiles of the former, which well agree with experiments. The temperature-dependent proximity of ${E}_{A1}$ and ${E}_{B1}$ to ${E}_{L}$ is reflected in the formation of Stokes dominated ${A}_{1}$ and anti-Stokes dominated ${B}_{1}$ temperature ``zones'' with a midpoint positioned at $T\ensuremath{\sim}260\text{ }\text{K}$. The shift in the frequency of the Stokes two-phonon dispersive band relative to that of the anti-Stokes band is explained as due to changing in the order of participation of the quasiacoustic phonon in the scattering process.