  Inelastic interaction of free-electrons with optical near fields has recently
attracted attention for manipulating and shaping free-electron wavepackets.
Understanding the nature and the dependence of the inelastic cross section on
the polarization of the optical near-field is important for both fundamental
aspects and the development of new applications in quantum-sensitive
measurements. Here, we investigate the effect of the polarization and the
spatial profile of plasmonic near-field distributions on shaping free-electrons
and controlling the energy transfer mechanisms, but also tailoring the electron
recoil. We particularly show that polarization of the exciting light can be
used as a control knop for disseminating the acceleration and deceleration path
ways via the experienced electron recoil. We also demonstrate the possibility
of tailoring the shape of the localized plasmons by incorporating specific
arrangements of nanorods to enhance or hamper the transversal and longitudinal
recoils of free-electrons. Our findings open up a route towards plasmonic
near-fields-engineering for the coherent manipulation and control of slow
electron beams for creating desired shapes of electron wavepackets.
