A New Method for Imaging Vibrations and Atomic Movements in Catalysts

A novel method for imaging atom vibrations and movements in catalysts has been developed by researchers. The new method identifies and locates individual atoms in nanoparticles even when they are vibrating and moving.

In recent years, a group of top electron microscopy and catalysis researchers has been working to determine the three-dimensional arrangements of atoms in nanoparticle catalysts used in chemical processes. Their research integrated experimental measurements with mathematical modeling.

A combination of experimental measurements and mathematical modelings has resulted in a new method for visualizing atoms in motion. Stig Helveg, professor and head of the Center of Excellence VISION at DTU, is part of the research team that developed the method for identifying individual atoms in nanoparticles. The findings were published in the peer-reviewed scientific journal Nature Communications.

Researchers have developed a novel method for imaging vibrations and movements of atoms in catalysts. The new method makes it possible to identify and locate the individual atoms in the nanoparticle, even if they are vibrating and moving.

As a result, a new method for identifying and locating individual atoms in nanoparticles, even when they are vibrating and moving, has been developed. Until now, it was assumed that atoms in nanoparticles would remain static during observations. However, the researchers’ analyses of 3D atomic-scale images revealed that the initial expectation is insufficient. Instead, the researchers used a new analytical method to reveal the atoms’ dynamic behavior.

The researchers chose to use a well-known catalytic nanoparticle material, molybdenum disulfide, in their work. Because the material’s atomic structure is well-known, it provided a good foundation for interpreting the research group’s 3D atomic-resolved images, which were compiled using the unique TEAM 0.5 electron microscope at Lawrence Berkeley National Laboratory, which has the highest picometre-scale resolution in the world.

The new method is described and published in the journal Nature Communications.

The movement of atoms within a material is referred to as diffusion. Atoms move predictably to eliminate concentration differences and produce a homogeneous, uniform composition. Nanoscale objects travel at high speeds and oscillate billions of times per second. Thermal (Brownian) motion occurs naturally, whereas stimulated movements underpin the functionality of nano-mechanical sensors and active nano-(electro/opto) mechanical devices.

Groundbreaking visualization of atomic movements

The new model ensures the identification of atoms

The mathematical model allows the individual atoms in the nanoparticle to be identified even when they are moving. The intensity and width of the atoms in the images are measured by the model.

“Until now, determining which atom we are looking at has been difficult due to blurring caused by the atoms’ oscillations. However, by taking oscillations into account, we can more precisely identify, for example, the location of individual sulphur or molybdenum atoms “Professor Stig Helveg of DTU Physics, a member of the research group, says.

The new model also allows for the correction of nanoparticle alterations in the form of oscillations caused by the illumination of energetic electrons in the electron microscope. As a result, it will be possible to focus on the chemical information hidden in the atom of the image by atom – which is the essence of the research.

The next step is measuring the function

The researchers hope that other researchers in their field will use the new groundbreaking model. The model will also serve as the foundation for Stig Helveg’s new basic research center at DTU, VISION.

The emphasis here will be on going a step further by combining atomic-resolution images with measurements of the catalytic properties of the nanoparticles. As part of the transition to sustainable energy, the knowledge gained will aid in the development of nanoparticles for catalytic processes.

Professor Helveg plans to use the new model and method as the foundation for future research at the Center of Excellence VISION, and he hopes that other researchers in the field will do the same. The atomic-resolution images will then be combined with measurements of the catalytic properties of the nanoparticles to determine their function. This step will direct researchers’ attention to another current and important topic: the development of nanoparticles for catalytic processes, which are required as part of the transition to sustainable energy.