keV Ultrafast Electron Diffraction
Ultrafast Electron Diffraction
About Research
A time-resolved reflection-type electron diffraction facility has been developed
for investigating atoms dynamics near the surface of crystalline materials.
When the electrons emitted from a cathode strike the surface of a specimen at a very small angle which can be decided by the energy of electrons, the electrons diffract from the atoms near the surface of the specimen.
The diffracted electrons interfere constructively according to the crystal structure of the specimen and the wavelength of the incident electrons to make spots on a detector positioned behind the sample. If we analyze the pattern and density of the spots after inducing atoms movement with electromagnetic waves, we can survey the interactions between electromagnetic waves and atoms. To do the pump and probe experiments, a photocathode electron gun was developed, which emit electrons of 10 keV during a short UV pulse hits the cathode.
The electron pulse length is several ps and the electron bunch can be focused to a size of 100 μm. And micro-channel plate is installed for amplifying the diffracted electrons as detector to make it easy to analyze the patterns. As pumping light sources, IR and THz wave are equipped in our system.