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KTH, Stockholm

Ultrafast Electron Microscopy, Applied Physics, KTH.

Director: Prof. Jonas Weissenrieder

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a) Research areas: We apply UEM, also called dynamic TEM, to follow the motion of atoms as they are in transition during changes in state of matter. Since chemistry takes place by a reorganization of atomic positions over Ångström length scales at speeds of km/s, processes are often completed at the femto- or picosecond time scales. Our UEM microscope, the first in Sweden, is able to capture images with a comparable, femtosecond, time resolution.

b) Strongpoint areas   We have developed an improved cathode geometry for optimising UEM and use finite element simulations to understand spatial distribution and temporal spread of electron bunches. Areas studied are ultrafast transitions in charge density waves in 1T-TaSe2, photon-induced near field electron microscopy (PINEM) on a silver nanowires sample, and energy dispersion of electron bunches photoemitted from different cathodes.