Three-dimensional direction-dependent force measurement at the subatomic scale

May 10, 2017

Osaka-- Atomic force microscopy (AFM) is an extremely sensitive technique that allows us to image materials and/or characterize their physical properties on the atomic scale by sensing the force above material surfaces using a precisely controlled tip. However, conventional AFM only provides the surface normal component of the force (the Z direction) and ignores the components parallel to the surface (the X and Y directions). To fully characterize materials used in nanoscale devices, it is necessary to obtain information about parameters with directionality, such as electronic, magnetic, and elastic properties, in more than just the Z direction. That is, it is desirable to measure these parameters in the X and Y directions parallel to the surface of a material as well. Measuring the distribution of such material parameters on the atomic scale will increase our understanding of chemical composition and reactions, surface morphology, molecular manipulation, and nanomachine operation.

A research group at Osaka University has recently developed an AFM-based approach called "bimodal AFM" to obtain information about material surfaces in the X, Y, and Z directions (that is, in three dimensions) on the subatomic scale. The researchers measured the total force between an AFM tip and material surface in the X, Y, and Z directions using a germanium (Ge) surface as a substrate. Their collaborative partner, the Institute of Physics of the Slovak Academy of Sciences, contributed computer simulations of the tip-surface interactions. The bimodal AFM approach was recently reported in Nature Physics.

"A clean Ge(001) surface has alternately aligned anisotropic dimers, which are rotated by 90° across the step, meaning they show a two-domain structure," explains first author Yoshitaka Naitoh. "We probed the force fields from each domain in the vertical direction by oscillating the AFM tip at the flexural resonance frequency and in the parallel direction by oscillating it at the torsional one."

The team first expressed the force components as vectors, providing the vector distribution above the surface at the subatomic scale. The computer simulation supported the experimental results and shed light on the nature of chemical tip termination and morphology and, in particular, helped to clarify the outstanding questions regarding the tip-surface distances in the experiment.

"We measured the magnitude and direction of the force between the AFM tip and Ge surface on a subatomic scale in three dimensions," says Naitoh. "Such measurements will aid understanding of the structure and chemical reactions of functionalized surfaces."

The developed bimodal AFM approach will allow researchers to investigate the physical properties of materials in greater detail on the nanoscale, which should facilitate development of devices, nanotechnology, and friction/lubrication systems.

Osaka University

Related Atomic Force Microscopy Articles from Brightsurf:

Ultracompact metalens microscopy breaks FOV constraints
As reported in Advanced Photonics, their metalens-integrated imaging device (MIID) exhibits an ultracompact architecture with a working imaging distance in the hundreds of micrometers.

Attosecond boost for electron microscopy
A team of physicists from the University of Konstanz and Ludwig-Maximilians-Universität München in Germany have achieved attosecond time resolution in a transmission electron microscope by combining it with a continuous-wave laser -- new insights into light-matter interactions.

Microscopy beyond the resolution limit
The Polish-Israeli team from the Faculty of Physics of the University of Warsaw and the Weizmann Institute of Science has made another significant achievement in fluorescent microscopy.

Quantum light squeezes the noise out of microscopy signals
Researchers at the Department of Energy's Oak Ridge National Laboratory used quantum optics to advance state-of-the-art microscopy and illuminate a path to detecting material properties with greater sensitivity than is possible with traditional tools.

High-sensitivity atomic force microscopy opens up for photosensitive materials
Research at Kanazawa University as reported in Scientific Reports demonstrates atomic force microscopy imaging that gets around the challenges of exciting very small cantilevers at their high megahertz resonance frequencies.

May the force be with you: Detecting ultrafast light by its force
A McGill research team has developed a new technique to detect nano-sized imperfections in materials.

Diverse amyloid structures and dynamics revealed by high-speed atomic force microscopy
Researchers at Kanazawa University report in ACS Nano a high-speed atomic-force microscopy study of the formation of protein fibrils (amyloids) associated with pathologies in collaborated research with Showa University.

Atomic force microscopy reveals nanoscale dental erosion from beverages
KAIST researchers used atomic force microscopy to quantitatively evaluate how acidic and sugary drinks affect human tooth enamel at the nanoscale level.

Limitations of super-resolution microscopy overcome
The smallest cell structures can now be imaged even better: The combination of two microscopy methods makes fluorescence imaging with molecular resolution possible for the first time.

High-end microscopy refined
New details are known about an important cell structure: For the first time, two Würzburg research groups have been able to map the synaptonemal complex three-dimensionally with a resolution of 20 to 30 nanometres.

Read More: Atomic Force Microscopy News and Atomic Force Microscopy Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to