Time-resolved optical spectroscopy

We utilize various time-resolved techniques to study dynamic processes, such as photocarrier recombination and the decay of optically induced spin and valley polarization, on timescales ranging from picoseconds to nanoseconds.

(a) Time-resolved photoluminescence of interlayer excitons reveals complex dynamics, which has 3 phases (b): (1) Diffusion of IEX in the inhomogeneous potential landscape. (2) Dipole-dipole interaction of IEX, which are trapped in potential minima (3) reduction of energetic shift with decreasing IEX density (see P. Nagler et al., Interlayer exciton  dynamics in a dichalcogenide monolayer heterostructure, 2D Mater. 4, 025112 (2017)).

(a) Time-resolved Kerr rotation measured on a WS2 monolayer shows the different dynamics of A and B exciton valley polarization (see G. Plechinger et al., Trion fine structure and coupled spin-valley dynamics in monolayer Tungsten Disulfide, Nature Comm. 7, 12715 (2016).) (b) Helicity- and time-resolved photoluminescence of GaSe bulk shows precession of a spin polarization in an applied magnetic field.