Resonant Raman scattering at exciton states tuned by pressure and temperature in $2H{\text{-MoS}}_{2}$

Resonant Raman scattering at exciton states tuned by pressure and temperature in $2 H {-MoS}_{2}$

Tsachi Livneh and Eran Sterer

Phys. Rev. B 81, 195209 – Published 18 May 2010

Abstract

We report on the temperature and pressure dependence of Stokes and anti-Stokes Raman spectra of a single crystal of $2 H {-MoS}_{2}$ as the energies of the $A_{1}$ and $B_{1}$ excitons, $E_{A 1}$ and $E_{B 1}$ , are tuned to resonate with an exciting laser at $E_{L} = 1.96 eV$ . Pressure- and temperature-dependent intensity ratio analysis of the resonant $A_{1 g}$ phonon and the $E_{2 g}^{1}$ phonon is complemented by the calculation of resonance Raman probability profiles of the former, which well agree with experiments. The temperature-dependent proximity of $E_{A 1}$ and $E_{B 1}$ 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 $T \sim 260 K$ . 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.