Time-resolved force microscopy using the delay-time modulation method

We developed a time-resolved force microscopy technique by integrating atomic force microscopy using a tuning-fork-type cantilever with the delay time modulation method for optical pump-probe light. We successfully measured the dynamics of surface recombination and diffusion of photoexcited carriers in bulk WSe2, which is challenging owing to the effect of the tunneling current in time-resolved scanning tunneling microscopy. The obtained results were comprehensively explained with the model based on the dipole-dipole interaction induced by photo illumination.