Physicists from the United States and Japan were able to capture the fluctuations of the dimeric fullerenes in carbon nanotubes with a resolution of 0.1 angstroms using electron microscope and high speed camera. In this case, scientists managed to increase the number of frames per second to 1600 — 100 times higher than the previous record. The study will help better understand the workings of molecular machines. Article published in the journal Bulletin of the Chemical Society of Japan.
Molecular machines are molecules that can move along certain directions or to perform useful work. For their creation of the Nobel Committee in 2016, was awarded the prize in chemistry. In the future, such devices can be used for targeted delivery of drugs and the creation of molecular electronics. One of the promising materials for the creation of molecular machines are considered to be carbon nanotubes, which can be used to create nandihalli and molecular switches.
In some machines of this kind are placed inside nanotubes of different molecules. However, when interaction with the walls of the nanotube, the molecules begin to move stochastically. However, their movement is impossible to describe using existing observations. Until now, scientists have managed to capture the processes occurring inside the nanotubes only at the rate of 12 frames per second with a resolution of two nanometers.
Researchers from the U.S. and Japan under the leadership of Professor Ehjjiti Nakamura (Eiichi Nakamura) from the University of Tokyo for the first time were able to capture the behavior of fullerene molecules inside carbon nanotubes at a speed of 1600 fps. For this they used aberration-corrected electron microscope, the camera direct detection of electrons and method of noise elimination based on the full variation, which today is also used to improve the quality of Internet video. Using these tools, the authors showed how nanotubes move along and rotate around its axis, the dimer of fullerene C60.
The researchers observed about 400 of nanotubes with fullerene molecules within 10 minutes. They found several tens of displacements of the dimers from one end of the structure to another. The scientists also saw for the first time that oscillations of the nanotube affect the rotation and movement of fullerenes inside her. It turned out that the kinetic energy of fullerene receive from the tube, causes them to rotate around its axis. In addition, this energy is sufficient to break the weak van der Waals interactions between the dimers C60 and get them to move inside the nanostructures. Move the fullerenes inside the nanotube also leads to substantial deformation by approximately 19 percent.
The results of the study allow a better understanding of the principle of operation of molecular machines based on nanotubes. In the future, scientists plan to increase the temporal and spatial resolution of the survey and a more detailed description of the processes in nanosystems of this kind.
High-speed camera enables to capture not only the motion of nanostructures, but also electromagnetic waves. In 2018, the researchers were able to capture the propagation of femtosecond laser pulse through a glass plate at a speed of 10 trillion frames per second.