Single-shot Picosecond Temporal Resolution Transmission Electron Microscopy

Transmission electron microscopy (TEM) is one of the primary tools for biological and materials characterization; however, there is an overarching need to push TEM temporal resolution into a ps-range to study physical processes on their fundamental spatial and temporal scales. With state-of-the-art TEM, however, it is not possible to capture a single image with a temporal resolution better than 10 ns due to the limits set by space charge effects in the electron column.
Technical Approach To address this limitation, UCLA and RadiaBeam Technologies are developing a single shot picosecond time resolved transmission electron microscope (SPTEM) with 10 ps temporal and 10 nm spatial resolution based on the use of MeV beams from an RF photoinjector to improve TEM temporal resolution by three orders of magnitude. Key elements include the use of RF cavity linearizer, and an ultra-compact optical column based on strong permanent magnet quadrupoles (PMQs) to avoid the large costs and complexities associated with bulky relativistic electron lenses. Phase II Accomplishments In Phase II, we have developed and commissioned the basic SPTEM system elements, including linearizer and PMQ optics. The highlights of previous work are: the first demonstration of single-shot images with ps-long MeV electron beams; and more recently, the demonstration of × 900 magnification using a two-stage permanent magnet quadrupole lens system. Phase IIa Work Plans In Phase IIa, we will build on the results obtained during Phase II to improve on the performances on the first prototype single shot picosecond TEM based on the existing infrastructure at the UCLA Pegasus laboratory. In particular we plan to improve on the electron beam stability, implement a flexible optical system that would allow for diffraction mode and adjustable magnification. We will also develop a new burst operating mode where multiple images of a process, ‘before’ and ‘after’, could be captured. The final goal of the project will be to test the instrument capabilities by performing a time-resolved study of motion of defects in a material. Commercial Applications and Other Benefits There are many exciting scientific challenges and commercial opportunities awaiting novel tools possessing very high combined spatial and temporal resolution, such as the device proposed herein. These include conformational changes in protein, interface dynamics in battery and fuel cells, and phase transition and microstructure development in materials. The device not only would enable further breakthroughs in the understanding of ultrafast phenomena but will also present RadiaBeam with a possibility to enter a lucrative microscopy and metrology instrumentation market.