Fig. 4: Ultrafast scanning electron microscope (SEM) based on the optical fiber-integrated graphene ultrafast hot-electron source.
From: Stable ultrafast graphene hot-electron source on optical fiber
a Schematic diagram of our ultrafast SEM. A traditional scanning microscope body is equipped with our optical fiber-integrated graphene ultrafast hot-electron source for spatial and temporal imaging. CL: Cathodoluminescence; TCSPC: Time-correlated single-photon counting; APD: Avalanche photodiode. b Images obtained from the ultrafast electron microscope using a secondary electron detector. High signal-to-background ratio images can be captured when the laser is turned on, benefiting from the pure pulsed electrons from graphene. c CL and far-field PL spectra of CdSe/ZnS quantum dots. d Time-resolved CL and PL spectra (circles) of CdSe/ZnS quantum dots. The exponential decay fitting (solid lines) gives decay lifetimes of CL (\({{\tau }}_{{{{{\rm{CL}}}}}}\)) and PL (\({{\tau }}_{{{{{\rm{PL}}}}}}\)) of 2.5 ns and 2.6 ns, respectively. The optical excitation at 1560 nm is transmitted via optical fiber.
