Millennium Post

Individual quantum dots imaged in 3D for first time

San Francisco: Researchers at the University of Illinois (UI) have developed an imaging technique that uses a tiny, super sharp needle to nudge a single nanoparticle into different orientations and capture 2D images to help reconstruct a 3D picture.
The method can demonstrate imaging of individual nanoparticles at different orientations in a laser-induced excited state, reports Xinhua.
The study, published in the Journal of Chemical Physics, focused on a class of nanoparticles called quantum dots.
These dots are tiny, near-spherical semiconductors used in technology like solar panels, live cell imaging and molecular electronics, the basis for quantum computing.
The researchers observed the quantum dots using a single-molecule absorption scanning tunneling microscope fitted with a needle sharpened to a thickness of only one atom at its tip.
The needle nudges the individual particles around on a surface and scans them to get a view of the quantum dot from different orientations to produce a 3D image.
The researchers said there are two distinct advantages of the new SMA-STM method when compared with the current technology called cryogenic electron tomography (CryoET).
"Instead of an image produced using an average of thousands of different particles, as is done with CryoET, SMA-STM can produce an image from a single particle in about 20 different orientations," said Martin Gruebele, the lead author.
"And because we are not required to chill the particles to near-absolute zero temperatures, we can capture the particles at room temperature, not frozen and motionless," Gruebele, who is also an UI chemistry professor, added.
The researchers looked at semiconductor quantum dots for the study, but SMA-STM method can also be used to explore other nanostructures such as carbon nanotubes, metal nanoparticles or synthetic macromolecules.
The researchers are working to advance SMA-STM into a single-particle tomography technique.
"For SMA-STM to become a true single-particle tomography technique, we will need to prove that our nudges do not damage or score the nanoparticle in any way while rolled around," Gruebele said.
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