Nobel Prize in Chemistry 2023 considered worthy Thanks to scientists Mungi Bavendi, Louis Bruce and Alexey Ekimov for the discovery and synthesis of quantum dots.
The laureates succeeded in creating particles so small that their properties were determined by quantum phenomena. (radiation processes, atomic and nuclear physics phenomena, condensed matter physics, chemical bonds). If the properties of particles are generally determined by the number of electrons in them, the properties of quantum particles depend on size.
Thus, the smallest quantum dots glow blue, medium-sized quantum dots glow green, and the largest quantum dots glow red or orange. Size is the only feature that distinguishes them and changes all their properties: thermal, magnetic, chemical, electrical, etc.
Ekimov and Bruce were the first to observe this effect in the 1980s.
What does stained glass have to do with it?
“Since ancient times, people have added cadmium, copper and other metals to transparent glasses, and when these are annealed, they come together into structures whose colors change depending on their size. Of course, ancient people knew nothing about quantum dots. It was discovered by Ekimov, who was experimenting with stained glass. “He was the one who realized that the size of the quantum structures that form metals in transparent glass is responsible for the color of the material,” the Director of the Institute, Doctor of Physical and Mathematical Sciences, Corresponding Member of the Russian Academy of Sciences, told Gazeta. .Ru. Ioffe Sergei Ivanov.
It turned out that during baking, some nanostructures (dots) appeared on the glass surface and these had surprising properties.
“There is no way to use quantum dots in glass; we had to find something to obtain them, for example, in a liquid environment. In the 90s, studies emerged in which the same metals were immersed in colloidal solutions and quantum dots were formed when these solutions were heat treated.
Now they were free in liquid, they could be isolated and studied independently: they were extracted, medicinal drugs were added to them, they were injected into the blood of animals. This gave rise to work at the border of three fields: chemistry, physics and biology,” Ivanov explained.
These points can be magnetized and medicine can be directed to the desired parts of the body, or a solution can be made to see the edges of the tumor.
“We are currently conducting experiments on quantum dots and their use in surgical operations. We created a liquid containing quantum dots that can be applied to a tumor.
Surgeons have a problem: The borders of the tumor are not visible. However, quantum dot liquid makes it possible to see the boundaries and depth of the tumor. When a laser beam is directed at these tissues, they begin to glow.
“We are now conducting in vitro experiments at MIPT with the hope of creating the most suitable fluid with quantum dots for use during operations,” Elena Petersen, head of the laboratory for neurobiological and molecular biological problems and bioscreening at MIPT, told socialbites.ca.
“like a sandwich”
The second method of obtaining quantum dots has already been implemented in semiconductor technologies due to the self-organization effect. To do this, another thin layer is applied to the surface of a semiconductor, as Ivanov said. Due to the difference in parameters, tension arises, which causes the sprayed material to collect in clusters. If they are then overgrown with the material located below, then we get objects from one material in another. This is how semiconductor quantum dots were created.
“It’s like a sandwich. Instead of a single thin layer, a plane with three atomic layers and islands whose dimensions are comparable to the mean free path of an electron. This technology was used to create semiconductor lasers,” explained the scientist.
Quantum dot lasers appeared in the USSR and are currently being actively developed, including in Russia. Their main application is telecommunications, where they are used to transmit information via fiber optic communications.
In this case, the electrical signal is converted into an optical signal and transmitted over fiber. Ivanov said most communications, including the Internet, occur through fiberglass. Quantum dots can also serve as a photon source for optical quantum computers and can also be used to establish quantum unhackable communications, as they require the energy of single photons.
“This is necessary for optical quantum computers that use photons as information carriers. Such technologies are currently actively developing in Russia,” Alexey Fedorov, head of the scientific group at the Russian Quantum Center and MISIS University, told socialbites.ca.
native of the USSR
Ekimov became a pioneer in the field of studying quantum dots: he was the first to demonstrate quantum effects of copper chloride nanoparticles. He also showed that particle size affects color.
“Alexei Ekimov graduated from the physics department of Leningrad State University, and in the 1970s our great scientist Evgeniy Fedorovich Gross took him to his laboratory at the Institute of Physics and Technology. Essentially, all optical spectroscopy and these are the effects that Aleksey Ivanovich discovered in glass, all this research started at the AF Ioffe Physico-Technical Institute.
Later, he moved to Ekimov State Optical Institute and started researching glasses that change color depending on the annealing temperature. Glasses were doped (alloyed – socialbites.ca) with copper, chlorine, cadmium, sulfur, selenium and other elements of the second and sixth groups of the periodic table. It turns out that during annealing these elements gather into nano-sized clusters,” told socialbites.ca, director of the AF Physico-Technical Institute, who works in the same laboratory with Nobel laureate Ioffe Sergei Ivanov.
In 1975, Ekimov was awarded the USSR State Prize in science and technology for his work on spin orientation. (angular momentum of the particle) electrons in semiconductors and received the title of Doctor of Physical and Mathematical Sciences in 1989.
It was named after the scientist who worked at the State Optical Institute in the early 1980s. SI. Vavilov developed and applied a method to produce nanometer-sized crystals in glassy matrices. He studied the optical and electrical properties of glasses containing nanocrystals of various semiconductors. As a result, he was able to determine the relationship between the sizes of these crystals and spectroscopic parameters.
Later, semiconductor nanocrystals and similar objects began to be called quantum dots. The beginning of his research in the world was initiated by Ekimov’s work. In addition to the Nobel Prize, the scientist also received the Wood Prize from the Optical Society of America for “the discovery of nanocrystalline quantum dots and pioneering work on their electronic and optical properties.”
Ekimov has lived in the USA since 1999 and works at the American private company Nanocrystals Technology Inc.
“I have known Alexey Ivanovich Ekimov for a very long time, since his first works on quantum nanocrystals appeared. We last saw each other about five years ago in Paris, at a conference dedicated to the discovery of quantum dots: after which he shared his plans for future work. Judging by his publications, he continues his active scientific work. Right now I’m looking at a photo of us drinking beer together,” said Alexander Baranov, Doctor of Physics and Mathematics, Professor of the International Scientific and Educational Center for Nanostructure Physics at ITMO.
He participated in discussions about the nature of the properties of quantum dots, as well as discussions about the possibility of using Raman scattering to characterize quantum dots. There were different hypotheses: some believed that the properties were related to the influence of size-dependent quantum effects, others believed that it was a matter of chemical composition or physical compression in the glass matrix. Of course, there is no doubt that the problem is quantum effects, Baranov said.
Family athlete and trophy collector
American chemist Mungi Bawendi woke up in the middle of the night to announce that he had won the award.
“It is an honour. I am sleepy, but at the same time I am shocked and flattered. The names of the winners were announced before the official announcement, but no one called me yet, I did not know that I had won. Many scientists work in this field and I did not imagine that I would be the one to receive the award,” said Bavendi .
Bawendi is a graduate of Harvard and the University of Chicago and currently serves as a professor in the department of chemistry at the Massachusetts Institute of Technology (MIT). According to him, the most important and difficult thing in his work is to find balance.
“I have never been able to get enough sleep and this continues throughout my life. Work and family; They compete for time. So you need to find a balance when you’re young and can afford not to sleep as much,” Bawendi told The Tech magazine.
Family plays an important role in the life of a chemist. He admits that, in addition to science and teaching, his daughter and sports are also of great importance to him:
“I have a daughter and I like to do different things with her and introduce her to my favorite activities. I take him skiing or swimming. I love running and doing sports. I hope he inherits that from me.”
According to him, he often goes to the gym instead of lunch. To keep himself in good shape, the scientist tries to exercise two or three times a week.
Another laureate, Louis Bruce of Columbia University, can be called a collector of scientific awards.
During his career, he received seven awards, not counting the last one: the Irving Langmuir Award in 2001, the Wood Award in 2006, the Kavli Award two years later, the Willard Gibbs Award a year later, and then the National Academy of Arts. Science awards US Chemical Sciences, Peter Debye and Bauer.
All awards were awarded to the scientist for his research on semiconductor microcrystals in colloidal solutions, which were later called quantum dots.
Ekimov was the first person to perform an experiment in which he demonstrated quantum effects. A few years later, Louis Bruce became the first to prove that they depend on the size of nanoparticles.
The American scientist had to combine his passion for physical chemistry with the study of the fundamentals of warfare at sea; The scientist then entered Rice University, which trained naval reserve officers.
After graduating in 1965, he was appointed as a petty officer, but fortunately his superiors agreed to give him a four-year leave to conduct postgraduate research. As a result, Bruce linked his life with science, became an employee of Columbia University and began working on his thesis.
According to Bruce, his great-grandfather was a French-born waiter who immigrated to New York in 1868, and his father was a businessman who graduated during the Great Depression.
“Apparently I inherited the ability to think abstractly from my mother, who taught mathematics at the University of Missouri. “I had an aptitude for math and science in high school, and I developed an interest in tools and machines while working at a local hardware store after school and on weekends.” remembers physicist.