Inelastic electron scattering at a single-beam structured light wave

Inelastic interactions between electrons and light occur in free space through the presence of ponderomotive potentials generated by light. Here, the authors demonstrate that the use of a single spatially structured traveling light beam modulates the final electron energy spectrum, exhibiting the formation of discrete energy sidebands. In free space, electrons undergo inelastic scattering in the presence of ponderomotive potentials generated by light pulses and standing light waves. The resulting modulated electron energy spectrum can exhibit the formation of discrete energy sidebands when multiple light beams are employed. Here, we demonstrate the inelastic scattering of slow-electron wavepackets at a propagating Hermite-Gaussian light beam. The pulsed Hermite-Gaussian beam thus forms a ponderomotive potential for the electron with sufficient momentum components, leading to the inelastic scattering and subsequent formation of discrete energy sidebands. We show that the resulting energy-gain spectra after the interaction are strongly influenced by the self-interference of the electrons in this ponderomotive potential. This effect is observable across various wavelengths, and the energy modulation can be controlled by varying the electron velocity and light intensity. By utilizing the vast landscape of structured electromagnetic fields, this effect introduces an additional platform for manipulating electron wavepackets.

Automated summary

In this study, the authors demonstrate the inelastic interactions between electrons and light in free space through the presence of ponderomotive potentials generated by light. By using a single structured traveling light beam, the authors modulate the final electron energy spectrum, resulting in discrete energy sidebands. In the presence of light pulses and standing light waves, electrons undergo inelastic scattering in free space, and multiple light beams can lead to the formation of discrete energy sidebands.