[1] V. Richards, Nat. Chem. 2016, 8, 1090.
[2] P.L Anelli, N. Spencer, J. F. Stoddart, J. Am. Chem. Soc. 1991, 113, 5131–5133.
[3] S. Erbas-Cakmak, D. A. Leigh, C. T. McTernan, A. L. Nussbaumer, Chem. Rev. 2015, 115,
10081–10206.
[4] T. Kudernac, N. Ruangsupapichat, M. Parschau, B. Maciá, N. Katsonis, R. S.
Harutyunyan, K. Ernst, B. L. Feringa, Nature 2011, 479, 208–211.
[5] R. A. Bissell, E. Cordova, A. E. Kaifer, J. F. Stoddart, Nature 1994, 369, 133−137.
[6] V. Balzani, M. Clemente-Leon, A. Credi, B. Ferrer, M. Venturi, A. H. Flood, J. F. Stoddart,
Proc. Natl. Acad. Sci. U. S. A. 2006, 103, 1178–1183.
[7] S. A. Vignon, T. Jarrosson, T. Iijima, H. R. Tseng, J. K. M. Sanders, J. F. Stoddart, J. Am.
Chem. Soc. 2004, 126, 9884−9885.
[8] B. W. Smith, M. Monthioux, D. E. Luzzi, Chem. Phys. Lett. 1999, 315, 31–36.
[9] H. Somoda, K. Hirahara, S. Akita, Y. Nakayama, Nano. Lett. 2009, 9, 62–65.
[10] J. H. Warner, Y. Ito, M. H. Rümmeli, T. Gemming, B. Büchner, H. Shinohara, G. A. D.
Briggs, Phys. Rev. Lett. 2009, 102, 1995504.
[11] T. Shimizu, D. Lungerich, J. Stuckner, M. Murayama, K. Harano, E. Nakamura, Bull.
Chem. Soc. Jpn. 2020, 93, 1079–1085.
[12] M. Sotomayor, K. Schulten, Science 2007, 316, 1144–1148.
[13] F. Hosokawa, T. Shinkawa, Y. Arai, T. Sannomiya, Ultramicroscopy, 2015, 158, 56-64.
[14] T. Shimizu, Master Thesis, 2018.
[15] S. Han, M. Yoon, S. Berber, N. Park, E. Osawa, J. Ihm, D. Tománek, Phys. Rev. B 2004,
70, 113402.
[16] M. Koshino, Y. Niimi, E. Nakamura, H. Kataura, T. Okazaki, K. Suenaga, S. Iijima, Nat.
Chem. 2010, 2, 117–124.
[17] A. W. Barnard, M. Zhang, G. S. Wiederhecker, M. Lipson, P. L. McEuen, Nature 2019,
566, 89–93.
[18] J. W. Kang, H. J. Hwang, J. Phys. Soc. Jpn. 2004, 73, 1077–1081.
[19] C. Ginard, P. Lambin, A. Dereux, A. A. Lucas, Phys. Rev. B. 1994, 49, 11425–11432.
[20] J. H. Warner, Y. Ito, M. H. Ruemmeli, B. Buechner, H. Shinohara, G. A. D. Briggs, ACS
Nano 2009, 3, 3037.
[21] M. Neek-Amal, N. Abedpour, S. N. Rasuli, A. Naji, M. R. Ejtehadi, Phys. Rev. E 2010,
82, 051605.
86
－Chapter 5－
Summary and Perspectives
87
In the present thesis, by combining an atomic-resolution electron microscope, a fast
shutter speed camera, and the optimized denoising algorithm for electron microscopy imaging,
I have succeeded in observing and analyzing in situ individual nanomechanical events such as
a single molecular shuttle coupled with mechanical vibration of the CNT container, as well as
chemical reactions of individual molecules at maximum sub-millisecond and sub-angstrom
resolution.
In Chapter 2, I investigated various noise reduction methods for TEM images with low
signal to noise ratio (SNR) values and concluded that the most appropriate denoising method
for electron microscopy molecular imaging is Chambolle total variation denoising algorism
with a collaborator, Dr. Joshua Stuckner. While the Chambolle denoising preserves molecular
edges of C60 molecules, which is indispensable for precise size and distance measurements,
noises are reduced to give a good SNR, improving the image contrast high. A fast shutter speed
camera gives noisy image (Figure 5.1a) due to less electron dose irradiated to the specimen, but
by applying the Chambolle denoising, I obtained clear molecular images suitable for structural
analyses (0.625 ms/frame image in Figure 5.1b and 1.875 ms/frame image in Figure 5.1c) with
keeping a time resolution of a millisecond. With this denoising method, I have successfully
achieved a temporal precision of 0.9 ms and a localization precision of 0.01 nm for imaging of
non-periodic molecular structures such as C60 molecules in a CNT. (Figure 5.1d). Submillisecond-level time-resolution electron microscopy images described here are the highest
time resolution with electron microscopy so far for imaging of dynamic molecular events.
1.01 0.90 nm
denoising
superimposition
Figure 5.1. Fast video imaging of C60 molecules with Chambolle total variation denoising and
superimposition. (a) A single-frame image of C60 molecules at 0.625 ms/frame (1600 fps)
without any image processing and (b) with Chambolle denoising. (c) A three-frame
superimposed image (1.875 ms/ frame) with Chambolle denoising. (d) Corresponding
molecular model of C60 molecules in a CNT. Scale bar: 1 nm.
Chapter 3
本章については, 5年以内に雑誌等で刊行予定のため，非公開．
88
第３章については, 5 年以内に雑誌等で刊行予定のため，非公開．
89
In Chapter 4, I elucidated the mechanism of a nanomechanical behavior of a molecular
shuttle by a recording of the 1600 fps video of a single molecular shuttle. From a series of TEM
images of an oligomer moving back and forth for three times (Figure 5.3a), I found that the
translation of the molecule occurred when the direction of the CNT vibration changes (Figure
5.3b and c), suggesting that the motion of molecules inside was induced by receiving an energy
from the vibrating CNT. In other words, the molecule and the CNT container as a whole behave
as a mechanically coupled oscillator, where the molecular motion is coupled with the
mechanical motion of the CNT.
1.5
0.5
0.5
0.1
500
500
ii
1500
iii
2000
1000
1500
2000
-0.1
-1
500
1000 1500 2000
time (ms)
-2
690 ms ii
0.1
996 ms iii 1508 ms
40
ms
0.5
29
ms
0.5
-0.5
-0.5
-0.5
CNT
vibration
y (nm)
1000
1025.00 — 1087.50 ms
1518.75 — 1581.25 ms
1519
1.0
1025
650.00 — 712.50 ms
1.5
650
y nm
oligomer
translation
x (nm)
x nm
CNT
vibration
y (nm)
a 587.50 — 650.00 ms
0.5
-1
1800
1600
-1
800 1000 1200 1200 1400 1600 1800
1400
-1
1000
600
11
ms
1200
800
1000
800
600
1000
800
600
600
400
400
1200
-0.1
time (ms)
Figure 5.3. SMART-EM video frames showing the motions of a C60 oligomer in a vibrating
CNT. (a) TEM imaging and (b) distance the analysis of shuttling C60 oligomer in a CNT.
(c) Expansion of 690, 996, and 1508 ms areas of CNT vibration. Scale bar: 1 nm.
90
In this thesis, by developing the sub-millisecond electron microscopic imaging
method, I explored the molecular world of sub-millisecond, which has never been observed
before by other conventional methodologies. The sub-millisecond SMART-EM technique will
open up a new field of stochastic dynamics of single molecules, elucidating the mechanism of
molecular conformational changes and the equilibrium state of chemical reactions, which are
more fundamental molecular behaviors. It is expected to be applied for the study of various
scientific phenomena from materials science to life science, which until now could only be
conducted in theoretical calculations. It will also give a great impact on the education of
students because unlike boring texts or simple figures, molecular videos are thought to be more
motivating students. There is a saying that “seeing is believing”. I strongly believe what I
observed with sub-millisecond SMART-EM imaging will innovate the world and open up the
science of the future.
91
...
論文の公開元へ
