  We report the first experimental demonstration of an electrostatic electron
orbital angular momentum (OAM) sorter, which can be used to analyze the OAM
states of electrons in a transmission electron microscope. We verify the sorter
functionality for several electron beams possessing different superpositions of
OAM states, and use it to record the electron beams OAM spectra. Our current
electrostatic OAM sorter has an OAM resolution of 2 in the units of h/bar - the
reduced Planck constant. It is expected to increase the OAM resolution of the
sorter to the optimal resolution of 1 in the future via fine control of the
sorting phase elements.
