indicate the magnitude
and directionof the force ofin theindicatesthe magnitude
theplane.
forceThein blth

Nanotechnologies / Materials

indicates the magnitudeof the forceforce
in the fieldheightmap.
direction.
(c)tendeTheophotoinducedThe

photoinduced force field map. The tendency to explain the results

Photocatalytic materials, Solar cells

evident.

evident.

ご自身の顔写真のご提供
Visualizing atomic-scale structures with the※１2.
opticalforce
印刷可能な解像度のものを電子ファイ
１2. ご自身の顔写真のご提供※ 印刷可能な解像度のものを電子ファイルにてご提供ください。

Department of Applied Physics, Graduate School of Engineering
Professor Yasuhiro Sugawara

Researchmap https://researchmap.jp/read0082006?lang=en

Department of Materials Engineering Science, Graduate School of Engineering Science
Professor Hajime Ishihara

Researchmap https://researchmap.jp/nonlocal

Nanotechnologies / Materials

Abstract
Nanoparticles are attracting attention as photofunctional materials for use in photocatalysts, solar cells, and other applications.
Near-field scanning optical microscopes can produce images thatreflect the optical properties of such samples, but observation withatomic-scale resolution has not been realized.
The research team has succeeded in imaging the near-field lightof composite nanoparticles, which are designed as high-performance photocatalytic materials, with a resolution of less than one
nanometer using a photo-induced force microscope that measures
the optical force (Figs. 1-2). The key to the high-resolution observation was the realization of observation in an ultra-high vacuum
and elimination of the effects of heat caused by light irradiation. By
observing the composite nanoparticles using multiple wavelengthsof light, we were able to confirm that the composite nanoparticles
had the chemical properties as designed by using light pressure
images approaching atomic resolution, and we also succeeded in
obtaining three-dimensional vector images of optical force (Fig. 3).
This achievement is expected to become a new fundamental technology for the design and evaluation of functional nanomaterials.

▍ Background & Results
Recently, a variety of nanoparticles with trapped electrons havebeen synthesized, and they are attracting attention as new photofunctional materials for photocatalysts and solar cells. In order toevaluate the optical functions of individual nanomaterials from a
microscopic viewpoint, it is necessary to excite the sample and observe the near-field light in the vicinity of the sample on an atomicscale. Until now, scanning near-field microscopes have been used
to observe the near-field light, but it has been impossible to obtainatomic-scale resolution.
The research team succeeded in achieving an order-of-magnitude higher resolution by dramatically increasing the force detection sensitivity of the photo-induced force microscope by operating
it in an ultra-high vacuum, and by reducing the effect of heat generation to the utmost limit by devising a unique timing for repeatedlight irradiation.
The quantum dots synthesized as high-performance photocatalytic materials were observed with photo-induced force microscopeusing light of different wavelengths, and the data were analyzed
theoretically. The results showed that the near-field optical images
were obtained with a spatial resolution of less than 1 nm, reflecting
the chemical properties devised to enhance the photocatalyticfunction. In addition, we succeeded in obtaining a three-dimensional vector image of the optical force.

▍sign and evaluation for the synthesis of new nanomaterials. Therefore, this technology is expected to become a new fundamental
technology for the realization of innovative photocatalytic and solar
cell materials in the future.

図１ (a) 光照射された走査型顕微鏡のプローブ先端と試料の間に働く力（光圧）を読み取る光誘起力顕微鏡の模式図。(b)(c)二種の光波長(600nm,520nm)で得られた光誘起力顕微鏡像。(d)光誘起力像の断面図。
光触媒として設計された電子エネルギー構造が反映されている。

Fig.1 (a) Schematic image of photoinduced force microscopy. (b)(c) Photo-induced force

Fig.1 (a) Schematic image of photoinduced force microscopy. (b)(c) Photo-inducedforce
microscopy images of a quantum dot measured
using different
微鏡の模式図。
(b)(c)二種の光波長(600nm,520nm)で得られた光誘起力顕微鏡像。
(d)光誘起力像の断面図。
nm).
(d) Photoinduced
force profiles
images. This reflects
the electronicenergy
光触媒として設計された電子エネルギー構造が反映されている。
wavelengths(600 nm,520nm).for(d)thePhotoinduced
force profiles
for theimages.
structuredesigned
photocatalysis.
This reflects
theforelectronicenergy structure designed for photocatalysis.

図１ (a) 光照射された走査型顕微鏡のプローブ先端と試料の間に働く力（光圧）を読み取る光誘起力顕
microscopy
images of a quantum dot measured using different wavelengths (600 nm,520Fig.1 (a) Schematic image of photoinduced force microscopy. (b)(c) Photo-induced force
microscopy images of a quantum dot measured using different wavelengths (600 nm,520nm). (d) Photoinduced force profiles for the images. This reflects the electronic energy
structure designed for photocatalysis.

Fig.2 (a) Atomic force microscopy image of a quantum dot. (b) Photoinduced

図２ (a) 試料の原子間力顕微鏡像（拡大図）。(b)試料の光誘起力顕微鏡像（拡大図）。(c)光誘起力顕微
force microscopy
image at 660 nm. (c) Photoinduced force profiles for the image.
鏡像の断面図。1nmを切る分解能が得られていることが分かる。

A spatial resolution of less than 1 nm has been obtained.
Fig.2 (a) Atomic force microscopy image of a quantum dot. (b) Photoinduced force
図２(a) 試料の原子間力顕微鏡像（拡大図）。(b)試料の光誘起力顕微鏡像（拡大図）。(c)光誘起力顕微

microscopy
imageを切る分解能が得られていることが分かる。
at 660 nm. (c) Photoinduced force profiles for the image. A spatial
鏡像の断面図。1nm
resolution of less than 1 nm has been obtained.
Fig.2 (a) Atomic force microscopy image of a quantum dot. (b) Photoinduced force
microscopy image at 660 nm. (c) Photoinduced force profiles for the image. A spatial
resolution of less than 1 nm has been obtained.

Fig. 3 (a) 3D force field mapping of the photoinduced force. (b) Experimentally
図３ (a) 光圧の３次元ベクトル計測の模式図。(b)計測による光圧の３次元ベクトル。カラーの矢印で面obtained
3D photoinduced force field map using the laser with 660 nm wavelength.
Colored arrows indicate the magnitude and directionof the force in the
内の力の大きさと方向を表す。白黒の濃淡は高さ方向の力の大きさを表す。(c)
光圧の３次元ベクトル理
plane.
The black and white shading indicates the magnitude of the force in the論計算図。実験で得られた画像の傾向がよく説明できている。
height direction. (c) Theoretically calculated 3D photoinduced force field map.
Thetendency to explain the results of experiments well is evident.
Fig. 3 (a) 3D force field mapping of the photoinduced force. (b) Experimentally obtained 3D
photoinduced force field map using the laser with 660 nm wavelength. Colored arrows
indicate the magnitude and direction of the force in the plane. The black and white shading

Significance of the research and Future perspective

Using this technique, we can observe the near-field light of nanostructures with atomic resolution, which will greatly improve the de-indicates the magnitude of the force in the height direction. (c) Theoretically calculated 3D
photoinduced force field map. The tendency to explain the results of experiments well isevident.
１2. ご自身の顔写真のご提供※ 印刷可能な解像度のものを電子ファイルにてご提供ください。

P a t e n t
Yamanishi, Junsuke; Ishihara, Hajime; Sugawara, Yasuhiro et al. Optical force mapping at the single-nanometre scale. Nature communications. 2021 Jun23; 12(1): 3865. doi: 10.1038/s41467-021-24136-2
URL https://resou.osaka-u.ac.jp/en/research/2021/20210623_2
K e y w o r d photo-induced force microscopy, optical force, near-field optics, nanoparticle
Tr e a t i s e

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