image: This is a TEM image of a nanofabricated diffraction hologram used to generate free electron vortices. The lighter stripes are 20 nm wide slits cut all the way through a 100 nm thick silicon nitride membrane. A small circular area of material remains at the center of the hologram to provide structural stability. The hologram encodes a large topological singularity, through the inclusion of 25 extra slits in the top part compared to the bottom part. When delocalized electrons are transmitted through the hologram, their wavefunctions evolve into multiple electron vortex beams propagating at discrete angles relative to one another. This image relates to an article that appeared in the Jan. 14, 2011, issue of Science, published by AAAS. The study, by Dr. McMorran at National Institute of Standards and Technology in Gaithersburg, Md., and colleagues was titled, "Electron Vortex Beams with High Quanta of Orbital Angular Momentum." view more
Credit: Image © B. McMorran/NIST