(color online) (a) Time-resolved Kerr rotation response measured at 10 K under excitation of right (σ⁺, violet trace) and left (σ⁻, blue trace) circularly-polarized pump laser with photon energy of 1.746 eV and probe energy of 1.701 eV. These two traces are fitted by a bi-exponential decay function shown in green and red lines, respectively. The inset shows the amplitude of transient Kerr rotation signals at near zero delay time as a function of the probe laser energy with pump energy of 1.746 eV. (b) Kerr rotation dynamics excited by a σ⁺-polarized pump pulse at 1.746 eV under different temperatures. The probe beam is set at the direct exciton resonance energy of 1.701 eV. (c) Temperature dependence of the depolarization time measured by TRKR.