​We have established and developed the second generation of four-dimensional (4D) scanning ultrafast electron microscopy (S-UEM) and demonstrate the ability to record time-resolved images (snapshots) of material surfaces with 650 fs and ~ 5 nm temporal and spatial resolutions, respectively.

Using S-UEM, we spatially and temporally visualize the charge carrier dynamics on the surface of InGaN NW arrays before and after surface passivation with octadecylthiol (ODT).

​Here, we precisely map the surface charge carrier dynamics of the CIGS before and after surface passivation in space and time.

​By visualizing different surface of CdSe single crystals, we show that the morphology, grains and nanostructure features of the material surface can impact the overall carrier relaxation processes.

​Using our S-UEM with a 650 fs and ~5 nm temporal and spatial resolutions, respectively, we show that time resolved imaging of the energy loss dynamics and carrier spreading on the surfaces of a densely packed array of InGaN nanowires (NWs) as a model system can be achieved now in real space.