Discovering Hidden Material Properties of MgCl2 at Atomic Resolution with Structured Temporal Electron Illumination of Picosecond Time Resolution

A combination of atomic resolution phase contrast electron microscopy and pulsed electron beams reveals pristine properties of MgCl2 at 1.7 Å resolution that were previously masked by air and beam damage. Both the inter‐ and intra‐layer bonding in pristine MgCl2 are weak, which leads to uncommonly large local orientation variations that characterize this Ziegler–Natta catalyst support. By delivering electrons with 1–10 ps pulses and ≈160 ps delay times, phonons induced by the electron irradiation in the material are allowed to dissipate before the subsequent delivery of the next electron packet, thus mitigating phonon accumulations. As a result, the total electron dose can be extended by a factor of 80–100 to study genuine material properties at atomic resolution without causing object alterations, which is more effective than reducing the sample temperature. In conditions of minimal damage, beam currents approach femtoamperes with dose rates around 1 eÅ−2 s−1. Generally, the utilization of pulsed electron beams is introduced herein to access genuine material properties while minimizing beam damage. Ultrafast atomic resolution electron microscopy is developed and applied to reveal the pristine material properties of MgCl2. The emerging tool is generally applicable and allows minimizing electron beam–induced damage processes by modulating phonon excitations in the time domain. The resulting damage retardation can be more efficient than temperature reduction.