A new type of electron monochromator, developed in the last decade, revolutionized electron energy loss spectroscopy in the electron microscope, by improving the energy resolution to 12 meV (at first) and eventually 3 meV. This 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. The limits on the energy resolution of the present monochromator will be analyzed, and a 2nd generation monochromator with improved optics will be designed, for building in Phase II. Phase I work will focus on theoretical calculations, and mechanical and electronic designs of a second-generation ground-potential monochromator with new features such as: more precise aberration correction (to 5th order), improved stability, and advanced, user-friendly autotuning software. A new operating mode will be developed that will allow beam currents up to about 100 pA without compromising meV-level energy resolution. Magnetic Johnson noise, the random electromagnetic field due to thermal motion of electrons in conductors, will be modeled theoretically, and a design that minimizes it will be developed. The spectrometer will be updated in parallel. A monochromator is half of a spectroscopy system, and total system performance, especially stability, is increasingly critical as resolution improves. 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.
