Max Planck Society Background
Advanced electron microscopy approaches, such as photon-induced near-field electron microscopy (PINEM), exploit simultaneous imaging of electron and photon interaction with a sample. Here, spectra of the electron energy loss/gain are recorded resolving the full electromagnetic properties of sample with regard to permittivity and permeability.
Whereas in the PINEM regime the physical dynamics of the sample are dominated by the photon interaction, the electron-energy loss spectroscopy (EELS) shifts the focus towards domination of electron interaction. However, conventional methods for evaluating electron-energy loss/gain spectra fail to consider pulsed electron beams or electron interaction with their back-scattered electric field. Hence up until today, the physical resolution limits, may they spatial, temporal or regarding energy, have not yet been fully exploited.
Scientists at the Max Planck Institute for Intelligent Systems have developed an improved method for evaluation of electron energy gain/loss spectra. This novel superposition method consists of two separate, full simulation steps, one for the incident laser field and a second for the incident electrons. It also considers both, the electron interaction with the electric fields due to the laser light and due to the electric field caused by electrons.
Starting from laser pulse parameters and electron trajectories, the method allows systematic investigation of electron energy loss/gain spectra due to interaction with a sample. Consequently, this method is capable of presenting the electromagnetic response of a sample with increased reliability and interpretability.
N. Talebi, W. Sigle, R. Vogelgesang, P. A. van Aken, “Numerical simulations of interference effects in photon-assisted electron energy-loss spectroscopy”. New Journal of Physics, 15, 053013 (2013)
Superposition method considering all aspects of electron and photon interaction with a sample
Considers pulsed electrons and pulsed lasers of arbitrary energies and broadening
Considers electron interaction with the back-scattered electric fields
Gaining electron energy gain/loss spectra with higher reliability and interpretability
Imaging technique featuring high spatial, high temporal and high energy resolution.