Dr. Daniel Knez
Austrian Center for Electron Microscopy and Nanoanalysis, Graz
Italian National Research Council Trieste - Instituto Officina dei Materiali
gives a talk on

Atoms in Motion: On the Impact of Swift Electrons on Mass Transport Phenomena at the Nanoscale

With recent advances in aberration corrected electron optics, scanning transmission electron microscopy (STEM) has proven its excellent capability of characterising nanomaterials. Due to the high current densities occurring in a highly focused electron beam interpretation of STEM data is often impeded by continuous beam induced sample changes [1]. This is especially true for systems with a high percentage of weakly bound surface or interface atoms, which is characteristic for nanoparticles and other nanoscaled materials. Hence, beam induced processes pose a main limitation to nanomaterial characterisation in the STEM.
We apply both experimental and computational methods to elucidate electron beam induced dynamics down to the single atom level. On the one hand, we perform time-resolved STEM experiments, which allow to observe the dynamics of clusters and single atoms under the controlled influence of the electron beam in situ. We perform experiments on supported metallic clusters at controlled temperatures as well as single adatoms on Si surfaces [2,3]. On the other hand, we develop a computational framework to simulate elastic electron damage processes in solids, to obtain deeper insights into the observed dynamics [4,5].

References:
[1] R.F. Egerton, Microsc. Res. Tech. 75, 1550–1556 (2012).
[2] T. Furnival, D. Knez, E. Schmidt et al., Appl. Phys. Lett, 113, 183104 (2018).
[3] D. Knez, P. Thaler, A. Volk et al., Ultramicroscopy, 176, 105 (2017).
[4] A. Santana, A. Zobelli, J. Kotakoski et al., Phys. Rev. B, 87 (2013).
[5] D. Knez, M. Schnedlitz, M. Lasserus, et al., Ultramicroscopy, 192, 69 (2018).