The picosecond barrier to high brightness electron pulses has been 
broken.

A 3rd generation electron gun has been designed that is 100x 
brighter with respect to diffraction than 3rd generation light sources. 
 

The importance of this advance is related to the intrinsic ability of 
electron diffraction to observe atomic details.  With the advent of 
femtosecond electron pulses it is now possible to capture full 
structural details of transition state processes.  In other words, 
watch chemical reactions occur in real time and actually watch the 
atoms move in response to the reaction forces --- make the 
"molecular movie" showing the death and birth of molecules.  Time-
resolved diffraction studies with this new technology have focused 
on strongly driven solid-liquid phase transitions of aluminum as a 
model problem.  The signal to noise and available diffraction orders 
were sufficiently high to give direct access to fluctuations leading to 
the disordering or melting process and the associated radial 
distribution function.  Referenced to the initial lattice structure, the 
information content of the time dependent radial distribution is 
analogous to two-time correlation studies of liquids using various 
coherence spectroscopies. However, there is an important 
distinction.  Femtosecond electron diffraction has the unique ability 
to directly connect the correlation function to atomic details. In 
effect, this work has atomically resolved a thermally sampled 
barrier crossing, a process common to all transition state 
processes.