دانلود گزارش کارورزی و کار آموزی

چکیده : 

In this paper, the design and implementation of a femtosecond-resolved ultrafast transmission electron

microscope is presented, based on a thermionic gun geometry. Utilizing an additional magnetic lens

between the electron acceleration and the nominal condenser lens system, a larger percentage of the

electrons created at the cathode are delivered to the specimen without degrading temporal, spatial

and energy resolution significantly, while at the same time maintaining the femtosecond temporal resolution.

Using the photon-induced near field electron microscopy effect (PINEM) on silver nanowires

the cross-correlation between the light and electron pulses was measured, showing the impact of the

gun settings and initiating laser pulse duration on the electron bunch properties. Tuneable electron

pulses between 300 fs and several ps can be obtained, and an overall energy resolution around 1 eV

was achieved.