Ultra-High Energy Resolution Electron Monochromator for Atomic Resolution Studies

C53-13a-271299A recent development in electron microscopes improved energy resolution ten times, enabling a new field of science: the study of atomic vibrations at the nanometer scale, down to single atoms. The proposed development will improve the energy resolution 3x further, extending the field to new areas including quantum information technology. A new type of electron monochromator, used together with a new spectrometer developed with SBIR support, has revolutionized electron energy loss spectroscopy in the electron microscope, by improving the energy resolution from 30-40 meV to 3 meV. This has led to vibrational spectroscopy with atomic resolution, orders of magnitude smaller than was possible previously. Applications include detecting the vibrations of a single Si atom, damage-free mapping of light atomic species including hydrogen, mapping the substitution of 12C by 13C in biological samples, and many more. If the energy resolution were improved further into the 1-2 meV range, the application space would grow into the field of quantum materials, and other fields of physics and biology. In Phase I, the limits of the first-generation monochromator were analyzed, and a second-generation monochromator with improved optics for better energy resolution was designed. In Phase II, the new design will be built and tested, with the goal of improving the energy resolution another factor of three. Phase II work will use theoretical modeling performed in Phase I phase to build and optimize a second- generation ground-potential monochromator. It will have major new features such as: more precise aberration correction (to 5th order), improved stability, higher immunity to noise (electronic, mechanical, and magnetic Johnson) and advanced, user-friendly autotuning software. A definitive experiment will be conducted to quantify the effect of magnetic Johnson noise, the random magnetic fields arising from the motion of thermal electrons, and its findings will be used to minimize the influence of the noise on the energy resolution. A new operating mode, developed in Phase I, will allow beam currents up to 100 pA and higher without compromising meV-level energy resolution. A monochromator is the key part of the spectroscopy system, but the spectrometer is just as important. We will update the spectrometer too, using the same principles as the new monochromator design. The total system performance, especially aberration correction and immunity to noise, will be optimized for the whole microscope system. The proposed development will enable new types of experiments and open a new frontier for researchers around the world who invest in this technology. It will also secure and extend a key technological lead of the only US-based electron microscope manufacturer.