Limits of electron and ion beam analysis
and their application to nanoscience

Canada (Edmonton) June 11, 2023
日本 (virtual): 2023 年 6 月 12 日
Free registration.
Hybrid meeting: virtual and in-person
Click here to join virtual Zoom meeting
Meeting ID: 812 8134 4380
Passcode: 102697

JSM-MSC Annual Joint Workshop

Sponsors4th Annual Joint Workshop
Microscopical Society of Canada&

Japanese Society of Microscopy
Canada (Edmonton & virtual): June 11, 2023
日本 (virtual): 2023 年 6 月 12 日
Registration not required for virtual attendees.
ZOOM Meeting ID: 812 8134 4380 Passcode: 102697
Hybrid meeting: virtual and in-person.
Limits of electron and ion beam analysis and their application to nanoscience
Electrons and ions allow imaging, chemical and structural analysis at sub-nanometer scale in many materials of interestto physical and biological sciences. The practical limits can arise from the instrumentation, the interactions responsible
for the measured signal and, ultimately, by radiation damage inflicted on the studied sample by the incident beam.
Presentations in this year’s symposium discuss the practical aspects of pushing the boundaries of electron and ion
microscopy instrumentation, and the practical problems applying the electron and ion beam analysis to real-world
samples in physical and biological sciences.

Workshop sponsors

time Edmonton
SundayJune 11, 2023

time 東京
MondayJune 12, 2023

Presenting author

4:55 – 5 pm

7:55 – 8 am

Ken Harada
Marek Malac

Opening remarks

5 – 5:30 pm

8 – 8:30 am

Takehito Seki

Direct Electromagnetic Field Imaging at Defects by Differential Phase
Contrast Scanning Transmission Electron Microscopy

5:30 – 6 pm

8:30 – 9 am

Nadi Braidy

Encapsulation of dyes in carbon nanohorns

6 – 6:30 pm

9 – 9:30 am

Cathal Cassidy

Gas-based charge compensation measured by off-axis holography inenvironmental TEM

6:30 – 7 pm

9:30 – 10 am

Martin Couillard

Disentangling EELS signals from optical modes in photonic andplasmonic nanoparticle dimers and trimers

7 – 7:30 pm

10 – 10:30 am

Kodai Niitsu

Magnetic configurations of a skyrmionic vortex stabilized in FeGe
nanoparticles

7:30 – 8 pm

10:30 – 11 am

Nabil Bassim

Insights about Atomic-Scale Heteroepitaxy based on Correlative Electron
Microscopy of Van der Waals Heterostructures

8 – 8:30 pm

11 – 11:30 am

Makoto Schreiber

Lensing charged particles with the magnetic vector potential

8:30 – 9 pm

11:30 – 12 noon

Makoto Kuwahara

Time-Resolved Measurement in TEM Using a Semiconductor
Photocathode9 – 9:30 pm

12 – 12:30 pm

Alyssa Williams

Improved Visualization of Bone Ultrastructure in 3D FIB-SEM

9:30 – 10 pm

12:30 – 13:00 pm

Natalie Reznikov

The ultrastructure of bone in 3D: A twist of twists

10 – 10:10 pm

13:00 – 13:10 pm

Shigeo Mori
Misa Hayashida

Closing remarks

On behalf of the Microscopy Society of Canada- Société du Microscopie du Canada (MSC-SMC), I am
honoured to welcome you to Canada and the Fourth Japan-Canada Microscopy Societies Joint Symposium
held at the in Edmonton, Alberta, Canada. Together, our two societies have been pushing the frontiers ofelectron microscopy with this exciting symposium, now in its fourth year.
This year’s symposium theme “Limits of electron and ion beam analysis and their application tonanoscience” will bring together the latest developments and eminent speakers from across Japan andCanada presenting ground-breaking research focusing on the practical aspects of pushing the boundaries ofelectron and ion microscopy instrumentation, overcoming challenges, and applying electron and ion beam
analysis to real-world samples across the physical and biological sciences.
Hosted this year as a satellite conference in association with the annual MSC meeting, the JSM-MSC
symposium has become a hallmark of our national meeting and an event looked forward to by all. Its
continued offering is strong evidence of the advancements in microscopy our societies are making together.
I extend my deepest thanks to the sponsoring organizations and volunteer organizers in Canada and Japan,
especially Ken Harada, Shigeo Mori, Misa Hayashida, and Marek Malac, who worked so tirelessly to bring
you this exciting meeting year after year.
We look forward to welcoming you to Canada (again!) next year for the 50th Anniversary of the MSC-SMC
and look forward to our next joint meeting in Japan.
I give my warmest welcome to all attendees, in-person or virtually, and wish you a good scientific meeting.
Best wishes,
Kathryn Grandfield
President, Microscopy Society CanadaOn behalf of the Japanese Society of Microscopy, it is my great pleasure and honor towelcome all the great scientists, young researchers, and students to the Fourth Annual
Joint Workshop of the Microscopy Society of Canada- Société du Microscopie du Canada(MSC-SMC) and the Japan Microscopy Society (JSM), which will be held on June 11th,
2023 in Edmonton, Alberta, Canada both in person and online.
This workshop, “Limits of electron and ion beam analysis and their application tonanoscience,” shares an insight into the latest research and state-of-the-art technologies
in electron and ion beam analysis, which gains immense interest from a broad range ofscientists and engineers. Nine renowned speakers from Canada and Japan will provide
their cutting-edge research and discuss current limitations and future breakthroughs in thefield. It will also provide an excellent networking opportunity for young researchers andstudents to develop lifelong friendships.
The strength and quality of this year’s workshop reflect the success of the multiple
preceding joint events that began in 2020. Each year, the relationship between thevolunteered organizers and the two societies strengthened, despite the difficulties inorganizing international meetings due to the COVID-19 pandemic. This year’s meetingmarks the start of a new stage in the post-pandemic collaboration between MSC-SMC
and JSM.
I look forward to an excellent meeting with great scientists from two countries and sharing
new and exciting research in electron microscopy and related technologies.
Yours sincerely,
Shigeo Okabe
President-ElectThe Japanese Society of Microscopy

I am very pleased to welcome representatives from Japan and Canada to the 4th annual workshopof the Japanese and Canadian Microscopy Societies here at the NRC’s Nanotechnology ResearchCentre (NRC-NANO) in Edmonton, Alberta. NRC is committed to supporting R&D in microscopy
and working with Japan as a priority international partner. Our Developmental and Analytical
Microscopy team not only maintains and improves a suite of microscopes on our site, but they
have also convened NRC researchers across Canada to bring more awareness of microscopy to thebroader research community. NRC-NANO has also developed the first open-source electron
microscope, known as the NanoMi, to build awareness of microscopy and also provide a platform
for development of new microscopy capabilities in a plug and play system.

We view Japan as a key partner in advancing microscopy in Canada, and I hope this workshop canseed new collaborations between our countries to advance the field as a whole. We have an
excellent track record of hosting and collaborating with Japanese students and researchers fromboth industry and academia, and I am very interested to expand on this success going forward.

Enjoy the workshop and best of luck with your research endeavors.

Andrew J. Myles, Ph. D.

Director, Research and Development, Nanotechnology Research Centre
National Research Council of Canada | Government of CanadaA message from the workshop organizers
The 4th joint symposium of the Japanese and Canadian microscopy societies, JSM and MSC, is about totake place.
The 4th symposium is being held only a short time after the Kurashiki (Japan) meeting. We are a satellite
symposium of the joint conference of MSC with the International Union of Microscopy Societies(IUMAS). Taking into account the short time gap between the Kurashiki meeting and the limitations on
number of attendees at IUMAS, we aimed at a modest size meeting in Edmonton.

The JSM-MSC is held in hybrid format to accommodate for the covid19 restrictions at the time of
meeting planning. It is our understanding that the convenience of hybrid meetings has become importantconsideration for participants. According to the tradition of the previous meetings, the online
participation JSM-MSC symposium is free of charge and open to everyone. It is our hope that the JSMMSC meetings will result in one-on-one researcher interactions between Japan and Canada, resulting in
new methods and applications of microscopy.

This year, we are pleased to have excellent speakers presenting at the JSM-MSC. The topics range fromphysics underlying electron and ion microscopies, to applications in biological and materials sciences.

We strive to make the JSM-MSC symposium a long-term feature for our societies. Please look forward
to the information on the 2024 meeting, likely in conjunction with the 50th anniversary meeting of MSC.

Marek, Misa, Ken and Shigeo
At your service
March 25, 2023

Direct Electromagnetic Field Imaging at Defects by Differential Phase Contrast
Scanning Transmission Electron Microscopy
Takehito Seki1,2* and Naoya Shibata1,3,4*
1.

Institute of Engineering Innovation, The University of Tokyo, Tokyo 113-8656 Japan
PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
3.
Nanostructures Research Laboratory, Japan Fine Ceramic Center, Nagoya 456-8587, Japan
4.
Quantum-Phase Electronics Center (QPEC), The University of Tokyo, Tokyo 113-8656, Japan.
* Corresponding author: seki@sigma.t.u-tokyo.ac.jp
2.

Aberration-corrected scanning transmission electron microscopy (STEM) is a powerful technique fordirectly observing atomic-scale local structures inside materials and devices. However, in ordinary
STEM, atomic-resolution observation of magnetic materials is essentially difficult, since high magnetic
fields are inevitably exerted on samples inside the magnetic objective lens. In recent years, we havesucceeded in developing a new magnetic objective lens system that realizes a magnetic field freeenvironment at the sample position. Using this new objective lens system combined with the state-ofthe-art higher order aberration corrector, direct atom-resolved imaging of magnetic materials is realized
in STEM [1]. This novel electron microscope (Magnetic-field-free Atomic Resolution STEM: MARS)
is expected to be used for research and development of advanced magnetic materials and devices.
On the other hand, new imaging possibilities in STEM has been widely explored owing to the rapid
development of segmented and pixelated detectors. Differential phase contrast (DPC) imaging is
considered to be one of the most useful imaging techniques because electromagnetic field distribution
inside materials and devices can be directly imaged in real space. Applying DPC imaging for atomicresolution STEM [2], it has been shown that the electric field distribution within single atoms andmagnetic field distribution of single atomic columns can be imaged [3,4].
By combining the magnetic-field-free STEM with DPC imaging technique, new possibility forcharacterizing local electromagnetic fields at crystalline defects has been opened. The current on-goingdevelopments and material applications especially for interfaces will be presented in the talk.
Acknowledgment:
The authors thank all the collaborators of this research, especially Y. Kohno, S. Toyama, S.D. Findlay and Y. Ikuhara
for their contribution to the works shown in this presentation. The authors acknowledge JST ERATO Grant Number
JPMJER2202, Japan. A part of this work was supported by JST SENTAN Grant Number JPMJSN14A and the JSPS
KAKENHI Grant numbers 20H05659, 19H05788, 17H06094.
References:[1] N. Shibata et al., Nature Comm. 10, 2380 (2019).
[2] N. Shibata et al., Nature Phys., 8, 611-615 (2012).
[3] N. Shibata et al., Nature Comm. 8, 15631 (2017).
[4] Y. Kohno et al., Nature 602, 234-239 (2022).

Encapsulation of dyes in carbon nanohorns
Fanny Casteignau1, Louka Yilmaz1, Mathilda Dano1, Armand Soldera2, Christian Ricolleau3, Richard
Martel4, Nadi Braidy1,5*1Department of Chemical and Biotechnological Engineering, Université de Sherbrooke, Sherbrooke,
Canada2
Department of Chemistry, Université de Sherbrooke, Sherbrooke, Canada
3
Laboratoire Matériaux et Phénomènes Quantiques, Université de Paris, Paris, France
4
Department of Chemistry, Université de Montréal, Montréal, Canada
5Institut Interdisciplinaire d’Innovation Technologique 3IT, Université de Sherbrooke, Sherbrooke,
Canada*nadi.braidy@usherbrooke.ca
Carbon nanohorns (CNHs) are ~50 nm long graphenic cones typically capped by a C60 and arranged in
inseparable aggregates of about 100 nm in diameter with a sea urchin structure1. Thanks to their hollow
structure, dyes can be encapsulated in CNHs to serve as chemical sensors. Giant Raman scattering wasobserved with α-6T dyes encapsulated in carbon nanotubes. A similar enhancement of the Raman signal
was observed by our group when this dye was encapsulated in CNHs. It was proposed that Giant Raman
scattering is due to the α-6T chains arranged in a J-configuration3. However, direct imaging coupled tosimulation is needed to better understand the Raman scattering phenomenon and help tailor new sensing
functionalities.
Here, we couple spherical aberration-corrected high-resolution electron microscopy (Cs-HRTEM), molecular dynamics, and TEM multi-slice methods to help understand the encapsulation behavior of dyesin CNHs. We investigate the impact of the CNHs morphology and the thermal oxidation annealing stepon the encapsulation yield and α-6T configuration within the horns. We show that α-6T chains alignalong the walls of the CNHs (Fig. 1). However, it was difficult to provide direct experimental evidenceof their J-configuration. Furthermore, our moleculara)b)c)dynamics study shows that the α-6T chains are preferentially attracted to the tip of the CNHs and otherdefects in the graphenic structure.
References:[1] Iijima S et al Chem Phys Lett (1999) 309 (3-4) 165[2] Karousis N et al Chem Rev (2016) 116 (8) 4850
[3] Gaufrès E et al Nature Photonics (2014) 8 (1) 72

Fig. 1 a) Eight α-6T in a CNH model that was used for b)
multi-slice TEM image simulation to compare with c) CsHRTEM micrograph of an α-6T encapsulated in a CNH.

Gas-based charge compensation measured by off-axis holography inenvironmental TEM
Cathal Cassidy1*, Makoto Tokoro Schreiber 2
1

OIST Graduate University, Onna-son, Okinawa, Japan.
Department of Physics, University of Alberta, Edmonton, Alberta, Canada*c.cassidy@oist.jp
2

When imaging samples with low electrical conductivity in an electron microscope, thesample can accumulate charge and distort the measurement. Charging effects have been wellinvestigated in scanning electron microscopy (SEM) but have been less studied in transmission
electron microscopy (TEM). One method of reducing charging effects is to coat the sample ofinterest with a thin conductive film such as carbon. This is for the most part an irreversible
treatment and is not desirable for all samples such as vitreous ice films in biological electron
microscopy. Another method to compensate beam-induced charging is through the introduction ofgas flow over the sample. This technique has been established in SEM [1] but has not been wellinvestigated in TEM.
In this work, we observe and quantify how different partial pressures of gas in an open-cell
type environmental TEM affect the charging process on dielectric thin films through off-axis
electron holography. We observe that the large phase-ramp present at the edge of a film in highvacuum conditions (Figure 1a) is largely eliminated when a certain partial pressure of gas is
introduced (Figure 1b) – indicating a significant reduction of charge on the film. Through thiswork, we extend on previous studies of how gaseous environments affect the electron holography
process [2] and TEM imaging in general.
In this talk, we present some initial results on the effect of electron dose, gas pressure,specimen material, and thickness upon the observed charging and compensation behavior, as
observed by off-axis electron holography. We discuss the utility of gas-flow as a reversible chargemodulation method which may aid studies of other processes such as mean inner potential
measurement and charging-induced specimen vibrations.
References:[1] D. A. Moncrieff, V.N.E Robinson, and L.B. Harris, Charge neutralization of insulating surfaces in the SEM
by gas ionization, J. Phys. D: Apply. Phys. 11 2315 (1978).
[2] J.A. Hyllested, M. Beleggia, Investigation of gas-electron interactions with electron holography,
Ultramicroscopy 221 113178 (2021).

Fig. 1. Phase maps, reconstructed from 300kV off-axis holograms, from a 20nm SiN membrane. (a) Standard
high vacuum case. (b) Same film region as (a) but with 1950 Pa N2 gas in the specimen area. There is a clear,charging-induced phase ramp in (a), which has been substantially reduced by the introduction of N2 gas in (b).

Disentangling EELS signals from optical modes in photonic and plasmonic
nanoparticle dimers and trimers
Martin Couillard 1*
1

Energy, Mining and Environment Research Centre, National Research Council Canada, Ottawa, ON,
Canada*martin.couillard@nrc-cnrc.gc.ca
Advances in electron-beam spectroscopies performed in an electron microscope with a sub-nanometerprobe have enabled unique access to optical properties for a wide range of nanostructures [1]. If wefirst consider a simple system, an individual sphere, two distinctive types of optical modes are expected:
the plasmonic and the dielectric resonances. Plasmonic resonances relies on the response of freeelectrons, whereas dielectric resonances originate from displacement currents due to oscillations ofbounded electrons. By bringing spheres in close proximity, unique optical features emerge from mode
splitting and shifting. In this presentation, we explore using EELS the optical properties of monomers,
dimers and trimers of plasmonic (Ag@SiO2) and dielectric (SiO2) quasi-spheres. For plasmonic dimers
and trimers (figure 1), EELS measurements display multiple intertwined optical modes. Maps extracted
from an independent component analysis (ICA) allow for the identification of local modes (bulk, vertices
and facets) along with delocalized modes (coupling of spherical modes). Five components, however, is
not sufficient to properly describe such a system. To analyze a larger number of components, we propose
to reintroduce spatial information, which is absent in ICA, in order to classify the various contributions.
For dielectric dimers (figure 2) and trimers, sharp peaks are observed below the silica bandgap, but atdifferent energies than predicted by simulations. Nonetheless, trends such as blue-shift displacements orenergy broadening are well reproduced, and confirm the coupling of optical whispering gallery modes[2]. In summary, our results emphasize the importance of experimental measurements, because of thehigh sensitivity of photonic resonances to optical constants of materials and the high sensitivity ofplasmonic resonances to morphological details.
References:[1] A. Polman et al., Nature Materials, 18, (2019), 1158.
[2] M. Couillard, arXiv:2110.02789 (2021)

Fig. 1 STEM image and EELS spectra (0.5eV – 5.5eV)
for 3 probe locations (top). Maps for 5 principal
components extracted from ICA (bottom).

Fig. 2. (a) STEM image of silica bisphere with electronprobe locations for simulated |H| maps in (b), experimental
spectra in (c) and simulated spectra in (d).

Magnetic configurations of a skyrmionic vortex stabilized in FeGe nanoparticles
Kodai Niitsu1*
1

National Institute for Materials Science, Research Center for Advanced Measurement andCharacterization, Tsukuba 305-0047, Japan*NIITSU.Kodai@nims.go.jp
For magnetic materials, confined geometries have become a versatile platform for engineering
their micromagnetic structures. In particular, the engineering of magnetic structures has been intensively
studied in two- and one-dimensional ferromagnets, wherein the magnetic domain structures
accommodate their own physical and microstructural features into reduced dimensions. In contrast, when
confined in zero dimensions (0D), i.e., in nanoparticles, sophisticated magnetic structures can stilldevelop under appropriate conditions, but such visualization remains challenging.
A magnetic skyrmion is an emergent topological magnetic texture with a string-like structure inthree dimensions but the form confined in 0D hosts is not evident. I and collaborators performed
multiangle electron holography (EH) on chemically synthesized isolated tetrahedral particles of B20type FeGe to reveal their internal magnetic configurations. Integrating EH observations andmicromagnetic simulations uncovered real-space magnetic configurations. Nanoparticles with sizes
comparable to the helical wavelength (∼70 nm for FeGe) can lead to the emergence of a novel skyrmionicvortex structure (Fig. 1) [1]. This texture shows excellent robustness against temperature without
applying a magnetic field; thus, a zero-field skyrmionic ground state is realized for a certain size rangeof tetrahedral particles.
Acknowledgment: The author thanks to all the collaborators of Y. Liu, A. C. Booth, X. Yu, N. Mathur, M. J. Stolt, D.
Shindo, S. Jin, J. Zang, N. Nagaosa and Y. Tokura. This work was partly supported by a Grant-in-Aid for Scientific
Research (B) (19H02418) and for Challenging Research (Exploratory) (19K22052) from the JSPS.
References:[1] K. Niitsu, et al., Nat. Mater., 21 (2022) 305-310.

Fig. 1 Skyrmionic vortex confined in a 145-nm FeGe tetrahedral nanoparticle. (A) A scanning electron―――

micrograph showing a nanoparticle. (B) Phase () map in the form of cos() from the [010], [011], and [111]directions (upper column) and corresponding nanobeam diffraction patterns (lower column). (C to E) TEM――

images along the [001], [011], and [010] directions. (F to H) Observed in-plane magnetic flux distributions
for the corresponding projections at 10 K. (I to K) Corresponding projections of the micromagnetic―

simulations. (L) Magnetic configuration of (I) integrated along the [001] direction. (M) Equi-spin surface
with the z-component of magnetization Sz = 0. (N) Magnetic configurations in cross-sectional planes normal
to the z-axis. All scale bars are 100 nm.

Insights about Atomic-Scale Heteroepitaxy based on Correlative Electron
Microscopy of Van der Waals Heterostructures
Hesham El-Sherif1, Joshua Robinson2, Nabil Bassim1,3
1.

McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L8, Canada
Pennsylvania State University, Old Main, State College, PA 16801, USA
3.
Canadian Centre for Electron Microscopy, Hamilton, ON, L8S 4L8, Canada
2.

Recently, the synthesis of various 2D materials confined at the epitaxial graphene/SiC interface has beenrealized through confinement heteroepitaxy (CHet). In this technique, atoms intercalate at the interface
of epitaxial graphene (EG) and silicon carbide (SiC) substrates via a thermal evaporation process,typically at 800 °C. While the EG is deliberately damaged using plasma to open intercalation holes prior
to the CHet process, the EG is found to be healed after the metal intercalation due to a metal catalytic
effect. The CHet process facilitates scalable and environmentally air-stable 2D metals and alloys overmillimeter-scale. CHet metals and alloys exhibit novel properties, such as enormous second harmonic
generation, superconductivity, and epsilon-near-zero behavior. Understanding the atomic structure ofthese van der Waals heterostructures yields insights into their growth dynamics, can help explain theirproperties, and point to factors influencing their scaleability for device applications.
Here, we use the contrast from scanning electron microscope (SEM) images to unlock the metalintercalation positions as well as the EG thicknesses. We applied multiple correlative electron
microscopy techniques for understanding the secondary electron (SE) emission that generates thecontrast in SEM images. Our correlative electron microscopy includes surface chemical maps in planview using auger electron spectroscopy (AES) and with Scanning-Transmission electron microscopy(STEM) imaging and electron energy-loss spectroscopy (EELS) obtained from multiple site-specificcross-sections. We also understand the origin of the SE emission related to the heterostructure's local
work function by correlating both experimental measurements and theoretical calculations of the surface
potential of these heterostructures. We also optimized the SEM imaging conditions – current, voltage,
contrast/brightness, and the SE detector – to efficiently augment the differential SEM contrasts, thus
providing a rapid characterization path using only the SEM to identify van der Waals heterostructure
growth morphology variations. Finally, we examine implications on materials growth based on the local
measurement of the top atomic layer of SiC and its positional relationship with the metal 2-D film aboveit.

Lensing charged particles with the magnetic vector potential
Makoto Schreiber1,*, Cathal Cassidy1, Menour Saidani1, Matthias Wolf1
1*

Okinawa Institute of Science and Technology, 1919-1 Tancha, Okinawa, Japan.
mschreib@ualberta.ca

The Aharonov-Bohm (AB) effect [1] demonstrates that charged particles passing in regions free ofelectromagnetic fields are affected either by the magnetic vector potential in a field-free region or nonlocally by an inaccessible field. The effect is usually considered with respect to an infinite-length
solenoidal coil. In this geometry, it has been shown analytically that charged particles passing by thesolenoid experience a step-shift in their phase. This step-shift in phase has been considered the defining
experimental signature of the AB effect.
In the present work [2], we show from theoretical considerations that in the case of a toroidal solenoid
coil, a small curvature is present in the phase profile of particles passing through the central hole of thetorus (Figure 1a). This curvature is quite small relative to the phase step, and has not been noted
previously in either theoretical or experimental work. This phase curvature causes a lensing effect which
can be made convex or concave depending on the particle charge polarity and current flow direction(Figure 1b). Additionally, the spherical aberration coefficient is of opposite polarity to the focal length.
Although these properties would appear to violate Scherzer’s conditions [3], they do not as the underlying
principle is different - lensing is caused by the magnetic vector potential rather than a magnetic field. We
present experiments with electron holography and Fresnel diffraction through toroidal micro-magnets
which support the existence of this effect. The physics of this effect and its consequences are discussed.
References:[1] Y. Aharonov and D. Bohm, “Significance of electromagnetic potentials in the quantum theory”, Phys. Rev. 115(1959).
[2] M.T. Schreiber, et al., “A new electromagnetic lensing principle using the Aharonov-Bohm effect”
arXiv:2301.09980 (2023).
[3] O. Scherzer, “Über einige Fehler von Elektronenlinsen”, Zeitschrift für Physik, 101 (1936).

Figure 1. a) Calculated phase profiles for an electron plane wave passing an ideal toroidal solenoid. The light green
areas within the dotted vertical lines represent regions inside the torus volume where magnetic field is present. The
dotted ellipse highlights the central hole of the torus which is field-free yet exhibits lensing curvature. b) Schematic of
how a toroidal solenoid coil can behave as a concave or convex lens for particles with negative or positive charge.

Time-Resolved Measurement in TEM Using a Semiconductor Photocathode
Makoto Kuwahara（桑原 真人）1, 2*, Takafumi Ishida（石田 高史）1, 2, Koh Saitoh（齋藤 晃）1,2,
Hideo Morishita（森下 英郎）3, Shota Kuwahara（桒原 彰太）4, Toshihide Agemura（揚村 寿英）5
1

Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya, 464-8601, Japan.
Graduate School of Engineering, Nagoya University, Nagoya, 464-8603, Japan.
3
Research and Development Group, Hitachi, Ltd., Kokubunji 185-8601, Japan.
4
Department of Chemistry, Faculty of Science, Toho University, Funabashi, Chiba 274-8510, Japan.
5
Hitachi High-Tech Corporation, Hitachinaka 312-8504, Japan.
*
kuwahara@imass.nagoya-u.ac.jp
2

Dynamic observations of nanoscale materials provide important information for the time evolution of
optical couplings, phase transitions, and energy relaxations in a local site. Ultrafast measurement inelectron microscopy using pulsed electron beams is a promising candidate for investigating high-speed
phenomena on the nanoscale. Furthermore, intense pulsed electron beam in transmission electron
microscope (TEM) enables single-shot imaging, which is expected to observe biological specimens ororganic material without electron-beam damage due to extracting information before thermalization of
injected energy into specimen.
We had begun developing a spin-polarized pulse-TEM (SPTEM), which comprises a semiconductor
photocathode with a negative electron affinity (NEA) surface for a polarized electron source and a 30keV TEM [1]. The SPTEM showed that high-quality electron beam, e.g., high brightness, high spinpolarization, long coherent lengths, picosecond response time and narrow energy width, is realized by
the semiconductor photocathode with an NEA surface (NEA-PC) in electron microscope [1,2]. However,observable thickness of specimen in the SPTEM is restricted due to the beam energy. Therefore, we have
newly developed time-resolved TEM (TRTEM) using an NEA-PC as pulsed electron source equipped to
the TEM column based on a 100-kV TEM instrument (HT7830, Hitachi High-Tech Corp.). The TRTEM
is operated with beam energies of up to 100 keV, which improves transmittance in a specimen andprovides higher brightness compared with previously developed 30-keV SPTEM. A thin GaAs film ona glass plate (Hamamatsu Photonics Inc.) was employed as a backside-illumination-type NEA-PC, andsurface treatments of this photocathode were conducted in an NEA surface preparation system in the
TRTEM. The electron beam was extracted from the flat surface of the photocathode with a high electricfield gradient of 8 MV/m at an acceleration voltage of 100 kV along with suppression of the space charge
effect (as a consequence of the high acceleration field gradient) [3].
Ultrafast phenomena in gold nanotriangles (AuNTs) stimulated by pulsed laser were investigated usingtransient electron energy-loss spectroscopy (TEELS) technique. This investigation was conducted in the
TRTEM under the average pumping laser power of 200 mW. The pulse durations of the pumping laser
for specimen irradiation and electron beam emission were 150 fs and 7 ps, respectively. Intensity
enhancement and energy width broadening of the energy loss peak were observed at the EEL peaks
associated with surface and bulk plasmons in the AuNTs [3]. The TEELS data showed two decay
processes on decay-times of 7.8 ps and longer than 100 ps that compensated for the relaxation times of
excited surface plasmons using transient absorption spectroscopy. The results also indicated that excitedelectrons on the surface and in the bulk had the same relaxation processes during both electron–phononand phonon–phonon interactions.
Acknowledgment:
The authors wish to thank Drs. I. Nagaoki, T. Kobayashi, and S. Kawai of Hitachi High-Tech, and L. Mizuno and R.
Yokoi. of Nagoya University for helpful support and encouragement. The authors also thank Drs. J. Sasabe and Y.
Matsuoka, of Hamamatsu Photonics for technical support with the semiconductor photocathode. This research was
supported by JSPS KAKENHI Grant Numbers 17H02737, 21H04637, Japan.
References:[1] M. Kuwahara et al., Appl. Phys. Lett. 101, (2012), 03310.
[2] M. Kuwahara et al., Appl. Phys. Lett. 105, (2014), 193101.
[3] M. Kuwahara, et al., Appl. Phys. Lett. 121, (2022), 143503.

Improved Visualization of Bone Ultrastructure in 3D FIB-SEM
Alyssa Williams1,2*, Tengteng Tang3, Aurélien Gourrier4,5, Nabil Bassim1,3,6, Kathryn Grandfield1,6
1.

School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada
Fibics Incorporated, Ottawa, Ontario, Canada
3.
Department of Materials Science and Engineering, McMaster University, Hamilton, ON, Canada
4.
Univ. Grenoble Alpes, LIPHY, F-38000, Grenoble, France.
5.
CNRS, LIPHY, F-38000, Grenoble, France
6.
Canadian Centre for Electron Microscopy, McMaster University, Hamilton, ON, Canada*
willia16@mcmaster.ca
2.

The nanoscale architecture of bone is founded on the arrangement of collagen fibrils and mineralplatelets. Elucidating the spatial relationship between these two constituents faces great challenge largely
due to the requirement for nanometer resolution and a large tissue volume of imaging in the range oftens of micrometers. Focused ion beam scanning electron microscopy (FIB-SEM) nanotomography
allows for 3D high-resolution imaging of nanoscale features and, coupled with advanced image
processing tools, key structural information can be extracted from datasets. Recent FIB-SEM studies
indicate that mineral clusters in ellipsoid shapes. Yet, the collagen fibril organization across the ellipsoidand its presence at the periphery are unclear. In this study, human tibial osteonal bone tissue was imaged
using FIB-SEM nanotomography and analyzed using fast Fourier transforms (FFT), inverse FFT and 3D
segmentation tools. FIB-SEM imaging revealed previously reported mineral clusters or “mineralellipsoids” and characteristic collagen banding. FFT and inverse FFT analysis was implemented toenhance the 67 nm periodicity associated with type I collagen fibrils, while 3D segmentation was used
to elucidate their spatial arrangement with respect to mineral ellipsoids. Collectively, these data show
the interwoven structure of the collagen fibrils and demonstrate the fibrils traversing the mineral ellipsoid
boundary from the periphery to the center. This work provides greater structural insight into thefundamental building blocks of bone tissue.
Acknowledgment: Canadian Centre for Electron Microscopy and Fibics Incorporated for the access to and expertiseon advanced electron microscopes. Funding is gratefully acknowledged from NSERC.
References:[1] Binkley et al. J Struct Biol (2020) 107615.
[2] Katz et al. Connect Tissue Res 21 (1989) 149–158.
[3] Raguin et al. Ssrn Electron J (2020).
.

Fig. 1 Collagen fibril and mineral ellipsoid association in osteonal bone tissue. A) Mineral ellipsoid structure withcollagen fibrils in (blue arrowhead) and around (yellow arrowhead) the ellipsoid. B) 3D view of collagen fibrils in andaround the mineral ellipsoid structure.

The ultrastructure of bone in 3D: A twist of twists
Daniel J. Buss1, Roland Kroeger2, Marc D. McKee1,3, Natalie Reznikov1,3,4*
1

Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill
University, Montreal, Quebec, Canada; 2Department of Physics, University of York, Heslington, York,
United Kingdom; 3Faculty of Dental Medicine and Oral Health Sciences, McGill University, Montreal,
Quebec, Canada; 4Department of Bioengineering, Faculty of Engineering, McGill University,
Montreal, Quebec, Canada*natalie.reznikov@mcgill.ca
Structural hierarchy of bone – observed across multiple scales and in three dimensions – is essential toits mechanical performance. While the mineralized extracellular matrix of bone consists predominantlyof carbonate-substituted hydroxyapatite, type I collagen fibrils, water, and noncollagenous organic
constituents, it is largely the 3D arrangement of these inorganic and organic constituents at each lengthscale that endow bone with its exceptional mechanical properties. Based on recent volumetric imaging
studies of bone using FIB-SEM tomography and STEM tomography, and earlier works spanning scales
up to the level of whole bones, we illustrate the self-similarity of nested structural motifs across several
orders of magnitude and link the hierarchical organization of bone to the ubiquity of spiral structure in
Nature. We discuss the omnipresence of twisted, curved, sinusoidal, coiled, spiraling, and braided motifs
in bone in at least nine of its twelve hierarchical levels – a visualization undertaking that has not beenpossible until recently with advances in 3D imaging technologies. We hypothesize that the twisting motif
occurring across each hierarchical level of bone is linked to enhancement of function, rather than being
simply an energetically favorable way to assemble mineralized matrix components. We propose that
attentive, further consideration of twists in bone tissue and in the skeleton at different scales will likely
enhance our understanding of structure–function relationships in bone.
Acknowledgment: Object Research Systems Inc., Natural Sciences and Engineering Research Council of Canada
References:[1] Buss et al., Journal of Structural Biology X, Vol. 6, (2022), 100057.
[2] Reznikov et al., Science, Vol. 360, (2018), eaao2189.

Fig. 1. This figure shows a micrometer-size mineraltesselle – a typical space-filling motif in mature bone,
imaged by FIB-SEM Slice&View tomography. The
spindle-shaped tesselle shows a gentle longitudinal twist
following the texture of co-aligned collagen fibrils inbone. Scale bar equals 500 nm.

Fig. 2. This figure shows a few hundred nanometer-sized
aggregate of bone mineral crystallites, imaged by STEM
tomography. The layers of merging and splitting
crystallites also subtly twist, and the overall shape of themineral aggregate is similar to that of the tesselle in Fig 1.
Scale bar equals 50 nm.

Alphabetical List of Presenters

Bassim, Nabil
Brady, Nadi
Cassidy, Cathal
Coulliard, Martin
Harada, Ken
Hayashida, Misa
Kuwahara, Makoto
Malac, Marek
Mori, Shigeo
Niitsu, Kodai
Reznikov, Natalie
Seki, Takehito
Schreiber, Makoto
Williams, Alyssa