Novel Ultrafast Electron Diffraction System

Time resolved measurement of atomic motion is one of the frontiers of modern science, and advancements in this area will greatly improve our understanding of the basic processes in materials science, chemistry and biology. One technique under active development in this area is ultrafast electron diffraction (UED). RadiaBeam, in collaboration with UCLA, proposes to develop an innovative, inexpensive, low-energy UED system, which allows to reconstruct a single ultrafast event with a single pulse of moderate energy electrons (100 keV). A novel Streaked Ultrafast Electron Diffraction (SUED) system, that allows the reconstruction of a single ultrafast event, is proposed. A high resolution (sub-100 fs) of a comparatively long ( & gt;20 ps) 100 keV electron bunch is attained by means of a radio-frequency (RF) deflecting cavity, located immediately after the sample, that streaks the diffracted electron beam transforming the temporal evolution of the diffraction pattern into a transverse image. In Phase I, detailed design and engineering efforts were performed on the 100 keV photocathode gun and the RF deflecting cavity. The complete system was designed and simulated, and Phase II fabrication plans were developed. In Phase II, the Streaked UED system will be built and tested. An initial pump-probe experiment has been planned at UCLA. Commercial Applications and Other Benefits: UED has already been used to produce groundbreaking results in a number of areas of materials science and chemistry. The SUED system that we propose here, with improved resolution and signal-to-noise ratio, would enable even further breakthroughs in the understanding of ultrafast phenomena, stimulating new innovations in material science, chemistry and biology. The SUED system will be readily affordable by even small laboratories.