Over the last decade a new research field has developed by combining electron microscopy with ultrafast lasers. Now "ultrafast electron microscopes" can be used to make movies of nanoscale (microscopic) processes that occur too quickly to observe with standard electron microscopes. This project will use an ultrafast electron microscope to study fundamental quantum mechanical phenomena such as the transfer of orbital angular momentum from light to electrons. This team will also explore how light can be used to compress electron pulses in time from picoseconds to tens of femptoseconds, and to shape the spatial properties of electron beams. Undergraduate students will gain research experience conducting these experiments with a low-energy ultrafast electron microscope, and this training will help prepare them for advanced studies or jobs in high tech industry. As another benefit to society, these experiments will demonstrate novel optical manipulation methods to control electron pulses with nanometer and femtosecond precision, and this in turn will advance the technical capabilities of electron microscopes.
This project will explore new techniques to efficiently control the spatial and temporal properties of short pulses of electrons. The first technique will use the Kapitza-Dirac effect to transfer orbital angular momentum from photons to electrons, enabling quantized transfer of orbital angular momentum between two different free particles. A successful demonstration of this experiment will show that light can be used to manipulate the spatial phase of an electron beam. The second technique that will be explored is the use of intense standing waves of light to compress electron pulses from picosecond durations to only a few femtoseconds. Current electron pulses used for ultrafast electron diffraction and microscopy are limited to about 100 femtoseconds, which leaves a variety of dynamical processes out of reach. Electron pulses with durations of a few femtoseconds will provide an opportunity to follow dynamical processes in structural and electronic nanoscale systems. In summary, this project will demonstrate control over the spatial and temporal properties of electron pulses with novel methods that can have an impact on imaging and quantum control techniques that are needed for physics, chemistry, and biology.
