Terahertz modulation of the trion resonance in MoSe2 monolayer

Here we report a pronounced redshift of the trion resonance in MoSe 2 monolayer induced by picosecond THz pulses. The kinetic energy gained by hot carriers due to absorption of THz radiation is transferred during the formation of the trion, leading to an effective redshift of its optical transition. By performing time resolved measurements, we have determined the electron cooling time (τ = 70 ps) and estimated the absorption at 7.7 THz (α = 0.3%). A quantitative model based on the Heisenberg equation of motion explains the experimental observations and reproduces the data with good accuracy.