東京大学大学院工学系研究科 総合研究機構
第17回「次世代電子顕微鏡法」講演会
2024年2月2日 14:00 ‒ 15:00 ハイブリッド開催

Studying the chemistry and electronic properties of encapsulated
molecular and atomic systems with monochromated STEM-EELS
Quentin M. Ramasse1,2, Demie Kepatsoglou1,31SuperSTEM Laboratory, Daresbury
Schools of Physics, Astronomy & Chemical and Process Engineering,
University of Leeds, UK
3
Department of Physics, Engineering and Technology, University of York, UK
2

There have been great strides in recent years in the development of high-resolution dose-controlled
electron microscopy methodologies for studying beam sensitive materials systems at highresolution. New and improved hardware, such as advanced aberration correctors andmonochromators, as well fast direct or hybrid electron detectors or beam ‘choppers’ have widened
the range of applicability of these techniques. State-of-the-art monochromated electron energy loss
spectroscopy (EELS) in the scanning transmission electron microscope (STEM), in particular,
offers the ability to map materials and atomic structures with an angstrom size electron beam andan energy resolution for EELS under 5meV. However, atomic and single molecular systems remainchallenging objects for electron microscopy, especially when attempting to study their chemistryor electronic structure using EELS, an inherently dose-intensive technique. Here, we report on
how encapsulated molecular and atomic systems provide ideal containers, or ‘nano test-tubes’, tostudy chemical reactions and electronic interactions in some of the most challenging materialssystems. The diameter of encapsulating carbon nanotubes and the irradiating electron dose can beused in conjunction to control chemical reaction rates between the molecules and the encapsulating
containers, as well as bond dissociation in the encapsulated structures. This approach wasdemonstrated in the cases of perchlorocoronene molecules [1], or of individual diatomic HF
molecules isolated within fullerene cages [2]. The steric and electronic constraints imposed by theencapsulating tubes can also be used to form novel material phases with unique electronicproperties, such as recently identified ‘pico-perovskite’ structures. These smallest conceivable
halide perovskites were imaged and mapped using STEM-EELS [3], revealing a wealth of hitherto
unknown crystalline structures whose electronic properties were further investigated using abinitio methods, based on these experimental observations. However, the mostly conducting natureof carbon-based containers can occlude electronic structure information in EELS experiments.
Wide-band-gap BN nanotubes, in contrast, offer the promise of directly measuring the electronicor optical response of individual encapsulated nanostructure, while the more complex interactions
with the host chemistry offer new avenues of investigation [4,5].
[1] K.L.Y. Fung et al., Phys. Chem. Chem. Phys.25, 9092 (2023)[2] J. Biskupek et al., ACS Nano 14, 11178-11189 (2020)[3] R. Kashtiban et al., Advanced Materials 35, 2208575 (2023)[4] J.W. Jordan et al., J. Am. Chem. Soc. 145, 1206-1215 (2023)[5] I. Cardillo-Zallo et al., ACS Nano, in press (2024)
主催: 「次世代電子顕微鏡法」社会連携講講座
e-mail: ishikawa@sigma.t.u-tokyo.ac.jp