Periodic Reporting for period 2 - EBEAM (Electron beams enhancing analytical microscopy)
Berichtszeitraum: 2022-01-01 bis 2023-06-30
Electron microscopy (EM) is a key technology to reveal the atomic structure and chemical composition of materials with (sub-)Ångström resolution. It is an essential technique to enable the breakthroughs that are needed to solve societal challenges in renewable energy technology, life sciences, and communication and quantum technology. To realize these breakthroughs, we require EM technology with ultrafast time scale, ultrahigh energy resolution, covering low-energy spectral ranges and several other capabilities, all of which are beyond the present state of the art.
The eBEAM project will:
1. Extend the range of spatially and temporally resolved spectral electron microscopy, with main emphasis on improved time and energy resolution; coincidence spectroscopy, and proving quantum entanglement in EM.
2. Demonstrate application potential in renewable energy, semiconductor metrology, materials science, and life sciences.
3. Develop prototype hardware components that will lead to commercial products to be retrofitted in commercial EMs
The eBEAM project brings together a proven consortium of EM experts that will integrate their complementary EM science and technology into completely new EM measurement modalities, exploiting the unique interactions between free electrons and optical light fields, and thereby combining ultrahigh spectral and temporal control with sub-Ångström spatial resolution. The project’s ambition is to demonstrate <20 fs time resolution and <1 meV energy resolution, and to open up the 4-400 neV (1-100 MHz) energy range, all inaccessible in EM so far. Using new correlation and coincidence modalities that have never been used in EM before, we will unveil new methods to probe selection rules, low-energy band structures, trace elements, and more.
The eBEAM project will:
1. Extend the range of spatially and temporally resolved spectral electron microscopy, with main emphasis on improved time and energy resolution; coincidence spectroscopy, and proving quantum entanglement in EM.
2. Demonstrate application potential in renewable energy, semiconductor metrology, materials science, and life sciences.
3. Develop prototype hardware components that will lead to commercial products to be retrofitted in commercial EMs
The eBEAM project brings together a proven consortium of EM experts that will integrate their complementary EM science and technology into completely new EM measurement modalities, exploiting the unique interactions between free electrons and optical light fields, and thereby combining ultrahigh spectral and temporal control with sub-Ångström spatial resolution. The project’s ambition is to demonstrate <20 fs time resolution and <1 meV energy resolution, and to open up the 4-400 neV (1-100 MHz) energy range, all inaccessible in EM so far. Using new correlation and coincidence modalities that have never been used in EM before, we will unveil new methods to probe selection rules, low-energy band structures, trace elements, and more.
In the first year of the project, we have made progress towards all of the three objectives listed above.
Objective 1
On the theoretical side, a roadmap was developed for achieving the targeted sub-meV, sub-fs and sub-Ångström resolution. We have also formulated a fully quantum-mechanical description of light, free electrons, and their interactions. On the experimental side, we demonstrated an energy resolution exceeding previous technologies by typically three orders of magnitude through ultrahigh-resolution electron energy gain spectroscopy. Moreover, in the low energy far-infrared range mapping of surface phonons was demonstrated by electron energy loss spectroscopy (EELS). On the cathodoluminescence (CL) side, we are developing software for spatially-resolved polarimetry and explored limits of pump-probe CL spectroscopy as well as CL photon correlations for continuous and pulsed electron beams. Using an event-based EELS detector, we demonstrated ns dwell-time EELS and consequently could implement EELS-CL coincidence experiments with sub-10 nm spatial resolution. Furthermore, EELS-CL coincidence measurements on photonic cavities demonstrated phase-matched electron light interaction and efficient electron phase modulation using low-power, continuous-wave excitation. We also realized energy-dispersive X-ray spectroscopy (EDX)-EELS coincidence measurements.
Objective 2
We demonstrated that CL can be used as a probe of coherent excitations in semiconducting materials, thereby extending the application area of CL. We also collaborated on the potential of correlating photon-induced near-field electron microscopy (PINEM), EELS and CL for plasmonic nanomaterials. Moreover, nanothermometry measured by electron excitation has been explored theoretically and experimentally opening the possibility to measure temperatures and thermal conductivity with high spatial resolution. By using alternative scan patterns in scanning transmission electron microscopy (STEM), we could significantly reduce beam damage in beam-sensitive samples opening up the possibility to measure atypical materials with electron microscopy. We also extended the information level that can be extracted for transition metal dichalcogenides by resolving the correlation between upper and lower polariton branches.
Objective 3
On the instrumentation front, we designed and implemented a laser incoupling module for a CL system. In addition, a retarding field analyzer and sensitive TimePix electron detector were installed and tested at the same SEM. The combination of components will enable novel PINEM experiments in a scanning electron microscope (SEM). Moreover, we are developing a system based on a beam modulator and fast electron detector. Coupled to a spectrum analyser, radio-frequency modulated electron excitation will become possible for spectral signatures in the ultralow-energy range. In addition, electron-driven photon sources were designed and implemented in a SEM allowing for correlative electron-photon measurements without using an external light source.
Objective 1
On the theoretical side, a roadmap was developed for achieving the targeted sub-meV, sub-fs and sub-Ångström resolution. We have also formulated a fully quantum-mechanical description of light, free electrons, and their interactions. On the experimental side, we demonstrated an energy resolution exceeding previous technologies by typically three orders of magnitude through ultrahigh-resolution electron energy gain spectroscopy. Moreover, in the low energy far-infrared range mapping of surface phonons was demonstrated by electron energy loss spectroscopy (EELS). On the cathodoluminescence (CL) side, we are developing software for spatially-resolved polarimetry and explored limits of pump-probe CL spectroscopy as well as CL photon correlations for continuous and pulsed electron beams. Using an event-based EELS detector, we demonstrated ns dwell-time EELS and consequently could implement EELS-CL coincidence experiments with sub-10 nm spatial resolution. Furthermore, EELS-CL coincidence measurements on photonic cavities demonstrated phase-matched electron light interaction and efficient electron phase modulation using low-power, continuous-wave excitation. We also realized energy-dispersive X-ray spectroscopy (EDX)-EELS coincidence measurements.
Objective 2
We demonstrated that CL can be used as a probe of coherent excitations in semiconducting materials, thereby extending the application area of CL. We also collaborated on the potential of correlating photon-induced near-field electron microscopy (PINEM), EELS and CL for plasmonic nanomaterials. Moreover, nanothermometry measured by electron excitation has been explored theoretically and experimentally opening the possibility to measure temperatures and thermal conductivity with high spatial resolution. By using alternative scan patterns in scanning transmission electron microscopy (STEM), we could significantly reduce beam damage in beam-sensitive samples opening up the possibility to measure atypical materials with electron microscopy. We also extended the information level that can be extracted for transition metal dichalcogenides by resolving the correlation between upper and lower polariton branches.
Objective 3
On the instrumentation front, we designed and implemented a laser incoupling module for a CL system. In addition, a retarding field analyzer and sensitive TimePix electron detector were installed and tested at the same SEM. The combination of components will enable novel PINEM experiments in a scanning electron microscope (SEM). Moreover, we are developing a system based on a beam modulator and fast electron detector. Coupled to a spectrum analyser, radio-frequency modulated electron excitation will become possible for spectral signatures in the ultralow-energy range. In addition, electron-driven photon sources were designed and implemented in a SEM allowing for correlative electron-photon measurements without using an external light source.
EBEAM puts together prominent exponents of basic research and industry in electron microscopy across Europe. Our goal is to establish a new gold standard in materials science and metrology by combining ultra-fast optics and electron microscopy. During the first reporting period, we have already achieved significant progress beyond the state-of-the-art to achieve that goal. We have pushed the theoretical and experimental borders. We achieved three orders of magnitude enhanced energy resolution, opened up the completely undiscovered ultralow energy range (infrared to radio-frequency) and developed novel coincidence experiments. We did not only develop novel hardware components to do so but also demonstrated the new physics and materials that can be studied by the new approaches. The future of the project will be to push those boundaries further and demonstrate completely new modalities by refining the developed hardware, workflows and measurement schemes, which will enable the application potential for even more materials systems. Moreover, we will focus on innovation and how the newly developed hardware and software can be brought to the market.
The already created impact is manifold. On the one hand, we contributed to the foundation of radically new technologies applied to atypical EM samples. This knowledge can now be used by other researchers to apply it to their material systems. In the future, we foresee that the further developed technologies will create a new market value in renewable energy, electronics, materials science and life sciences markets. On the other hand, due to the close collaboration of all EBEAM partners Europe is at the forefront of EM research. We are already now training a new generation of scientists and engineers to ensure that this will be the case in the future as well.
The already created impact is manifold. On the one hand, we contributed to the foundation of radically new technologies applied to atypical EM samples. This knowledge can now be used by other researchers to apply it to their material systems. In the future, we foresee that the further developed technologies will create a new market value in renewable energy, electronics, materials science and life sciences markets. On the other hand, due to the close collaboration of all EBEAM partners Europe is at the forefront of EM research. We are already now training a new generation of scientists and engineers to ensure that this will be the case in the future as well.