Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Individual impurity atoms detectable in graphene

13.04.2018

A team including physicists from the University of Basel has succeeded in using atomic force microscopy to clearly obtain images of individual impurity atoms in graphene ribbons. Thanks to the forces measured in the graphene’s two-dimensional carbon lattice, they were able to identify boron and nitrogen for the first time, as the researchers report in the journal Science Advances.

Graphene is made of a two-dimensional layer of carbon atoms arranged in a hexagonal lattice. The strong bonds between the carbon atoms make graphene extremely stable yet flexible. It is also an excellent electrical conductor through which electricity can flow with almost no loss.


Using the atomic force microscope’s carbon monoxide functionalized tip (red/silver), the forces between the tip and the various atoms in the graphene ribbon can be measured.

Image: University of Basel, Department of Physics

Graphene’s distinctive properties can be further expanded by incorporating impurity atoms in a process known as “doping”. The impurity atoms cause local changes of the conduction that, for example, allow graphene to be used as a tiny transistor and enable the construction of circuits.

Targeted incorporation

In a collaboration between scientists from the University of Basel and the National Institute for Material Science in Tsukuba in Japan, Kanazawa University and Kwansei Gakuin University in Japan, and Aalto University in Finland, the researchers specifically created and examined graphene ribbons containing impurity atoms.

They replaced particular carbon atoms in the hexagonal lattice with boron and nitrogen atoms using surface chemistry, by placing suitable organic precursor compounds on a gold surface. Under heat exposure up to 400°C, tiny graphene ribbons formed on the gold surface from the precursors, including impurity atoms at specific sites.

Measuring the strength of the atoms

Scientists from the team led by Professor Ernst Meyer from the Swiss Nanoscience Institute and the University of Basel’s Department of Physics examined these graphene ribbons using atomic force microscopy (AFM). They used a carbon monoxide functionalized tip and measured the tiny forces that act between the tip and the individual atoms.

This method allows even the smallest differences in forces to be detected. By looking at the different forces, the researchers were able to map and identify the different atoms. “The forces measured for nitrogen atoms are greater than for a carbon atom,” explains Dr. Shigeki Kawai, lead author of the study and former postdoc in Meyer’s team. “We measured the smallest forces for the boron atoms.” The different forces can be explained by the different proportion of repulsive forces, which is due to the different atomic radii.

Computer simulations confirmed the readings, proving that AFM technology is well-suited to conducting chemical analyses of impurity atoms in the promising two-dimensional carbon compounds.

Original source

Shigeki Kawai, Soichiro Nakatsuka, Takuji Hatakeyama, Rémy Pawlak, Tobias Meier, John Tracey, Ernst Meyer, Adam S. Foster
Multiple heteroatom substitution to graphene nanoribbon
Science Advances (2018), doi: 10.1126/sciadv.aar7181

Further information

Prof. Dr. Ernst Meyer, University of Basel, Department of Physics, tel. +41 61 207 37 24, email: ernst.meyer@unibas.ch

Reto Caluori | Universität Basel
Further information:
http://www.unibas.ch

More articles from Physics and Astronomy:

nachricht The magic wavelength of cadmium
16.09.2019 | University of Tokyo

nachricht Tomorrow´s coolants of choice
16.09.2019 | Helmholtz-Zentrum Dresden-Rossendorf

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Tomorrow´s coolants of choice

Scientists assess the potential of magnetic-cooling materials

Later during this century, around 2060, a paradigm shift in global energy consumption is expected: we will spend more energy for cooling than for heating....

Im Focus: The working of a molecular string phone

Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Potsdam (both in Germany) and the University of Toronto (Canada) have pieced together a detailed time-lapse movie revealing all the major steps during the catalytic cycle of an enzyme. Surprisingly, the communication between the protein units is accomplished via a water-network akin to a string telephone. This communication is aligned with a ‘breathing’ motion, that is the expansion and contraction of the protein.

This time-lapse sequence of structures reveals dynamic motions as a fundamental element in the molecular foundations of biology.

Im Focus: Milestones on the Way to the Nuclear Clock

Two research teams have succeeded simultaneously in measuring the long-sought Thorium nuclear transition, which enables extremely precise nuclear clocks. TU Wien (Vienna) is part of both teams.

If you want to build the most accurate clock in the world, you need something that "ticks" very fast and extremely precise. In an atomic clock, electrons are...

Im Focus: Graphene sets the stage for the next generation of THz astronomy detectors

Researchers from Chalmers University of Technology have demonstrated a detector made from graphene that could revolutionize the sensors used in next-generation space telescopes. The findings were recently published in the scientific journal Nature Astronomy.

Beyond superconductors, there are few materials that can fulfill the requirements needed for making ultra-sensitive and fast terahertz (THz) detectors for...

Im Focus: Physicists from Stuttgart prove the existence of a supersolid state of matte

A supersolid is a state of matter that can be described in simplified terms as being solid and liquid at the same time. In recent years, extensive efforts have been devoted to the detection of this exotic quantum matter. A research team led by Tilman Pfau and Tim Langen at the 5th Institute of Physics of the University of Stuttgart has succeeded in proving experimentally that the long-sought supersolid state of matter exists. The researchers report their results in Nature magazine.

In our everyday lives, we are familiar with matter existing in three different states: solid, liquid, or gas. However, if matter is cooled down to extremely...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Society 5.0: putting humans at the heart of digitalisation

10.09.2019 | Event News

Interspeech 2019 conference: Alexa and Siri in Graz

04.09.2019 | Event News

AI for Laser Technology Conference: optimizing the use of lasers with artificial intelligence

29.08.2019 | Event News

 
Latest News

Too much of a good thing: overactive immune cells trigger inflammation

16.09.2019 | Life Sciences

Scientists create a nanomaterial that is both twisted and untwisted at the same time

16.09.2019 | Materials Sciences

Researchers have identified areas of the retina that change in mild Alzheimer's disease

16.09.2019 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>