PEEM with high time resolution—imaging of transient processes and novel concepts of chromatic and spherical aberration correction

Abstract

The potential of time-resolved photoemission electron microscopy (PEEM) for imaging ultrafast processes and for aberration correction in full-field imaging is discussed. In particular, we focus on stroboscopic imaging of precessional magnetic excitations via XMCD-PEEM exploiting the time structure of synchrotron radiation (magnetic field pulse pump-X-ray probe). In a special bunch-compression mode at BESSY, a time resolution of about 15 ps has been obtained. Further, we discuss an all-optical pump-probe technique using femtosecond laser excitation. A highly promising alternative to stroboscopic imaging is an approach using time-resolved image detection. As a second application of time-resolved PEEM we discuss potential ways of aberration correction. These approaches go back to the old ideas of Scherzer in the light of stateof-the-art equipment. The excellent time structure of synchrotron radiation or pulsed lasers along with advanced methods of time-resolved image detection and fast electronic pulsers opens ways for driving the resolution limit of a PEEM into the range of a few nanometers.

Correction of the deterministic part of space–charge interaction in momentum microscopy of charged particles

“…For the assumed parameter set the GPT calculation predicts a gain in energy-resolution by an order of magnitude. Last but not least, the results are important for new strategies of beam correction via further development towards dynamic aberration correction as discussed previously [28,29].…”

Single-Particle Phenomena in Magnetic Nanostructures

“…This method permits microscopy options with a spatial resolution in the range of tens of nanometers [210,211], making it an excellent technique for the study of nanomagnetism. Further developments were made possible by exploiting the pulsed nature of synchrotron radiation, conferring the potential for dynamic studies of magnetization processes using pump-probe methodologies [212]. The pulse duration using X-rays defines the ultimate limit of temporal resolution available, as with all pump-probe measurements, which in this case is of the order of 50-100 ps, which is sufficient to observe various magnetic processes, such as the precessional dynamics of ferromagnetic resonance (see Section 2.2.3), relaxation mechanisms, and vortex gyrotropic motion in magnetic nanoelements [213,214].…”

LEEM and PEEM as Probing Tools to Address Questions in Catalysis

“…The time interval between the pulses (Δt) will determine ultimately the time scale of the observed processes (fs or ps). In this sense, the nature of the pulses can have different origin, depending on the properties that want to be studied (for more details see [77]), making also use of the possibilities offered by third generation synchrotron storage rings. For example, magnetic pulses followed by light pulses can give some information on the surface domain reorganization dynamics in magnetic systems by using XMCD [75].…”