The size of the nanoparticles known as quantum dots, which were discovered and produced by Alexei Ekimov, Louis Brus, and Moungi Bawendi, determines their characteristics. (Nobel)
Assume for a moment that everything in the world contracted to a nanoscale. Many things would appear different, even though it isn’t immediately clear. The Royal Swedish Academy of Sciences cited the following examples: a gold ring would appear ruby red, while gold earrings would abruptly change blue.
Why should the colors of two gold ornaments differ?
The three scientists selected for the Chemistry Nobel Prize on Wednesday identified, investigated, and capitalized on the notion that their disparate sizes would determine their properties in the enigmatic quantum world.
Alexei I. Ekimov of Nanocrystals Technologies Inc., New York, Louis E. Brus of Columbia University, and Moungi G. Bawendi of MIT shared the Nobel Prize for the discovery and production of “quantum dots,” which are particles whose size determines their characteristics. One of the bases for nanotechnology, which has uses in everything from electronics to surgery, was established by their work.
Size is important. Quantum effects are a word used in the quantum realm to characterize the peculiar phenomena that occur. Scientist Herbert Fröhlich predicted in 1937 that nanoparticles would not behave like larger particles. Other researchers also predicted different quantum effects that were dependent on nanoparticle size.
The flow of electrons is the reason why nanoparticle size determines their characteristics. The motion of electrons and “holes,” or voids in energy positions that once held electrons, govern the majority of a material’s physical characteristics. This movement, when restricted, modifies a band gap property that is otherwise distinct for each and every material. Color is one of the many other qualities that change as a result.
In most materials, the effective dispersion of electrons and holes is quite minimal. The electron and hole energies in a given material are greatly shifted when a particle is reduced to a size that is comparable to these effective sizes of electrons and holes. This phenomenon is known as the confinement effect, and it affects not just the color but also many other properties, including the band gap, according to D D. Sarma, an Indian Institute of Science (IISc) chemistry professor.
How to make quantum dots The real creation of quantum dots did not occur until the late 1970s. Ekimov, a physicist at the SI Vavilov State Optical Institute in the Soviet Union at the time, was perplexed by the fact that depending on the degree of heating and cooling, a mixture of cadmium sulphide and selenium selenide could tint glass either red or yellow. Why should two different colors be produced from the same mixture?
Ekimov created copper chloride-tinted glass, which he then X-rayed to reveal microscopic copper chloride crystals. At the nanoscale, the larger particles started to absorb bluer and bluer light, yet they still functioned like copper chloride does usually. This was the first time a size-dependent quantum effect had been seen. In 1981, Ekimov published his results.
In 1983, Brus released his own research results on the other side of the Iron Curtain. long employed at Bell Laboratories in the United States, Brus discovered that after leaving cadmium sulphide particles on a bench for a long, they changed in optical characteristics. Like Ekimov, he produced smaller particles and discovered that the tiniest ones possessed size-dependent optical characteristics.
Brus created nanoparticles that varied in size and frequently had flaws. The approach was refined by Bawendi, who entered MIT in 1988 and started his postdoctoral training under Brus. His lab created simple procedures in 1993 that could yield nearly flawless nanocrystals exhibiting quantum phenomena. The field was revolutionized by this.
Useful applications Quantum dots found more and more applications as research expanded.
According to Mrinmoy De, an organic chemistry professor at IISc whose work involves the use of quantum dots for biological and catalytic applications, “one of the most popular applications of quantum dots in electronics.”
“The LED screen’s bright emissions, in terms of color, are determined by the individual photophysical properties of the quantum dots. A further use is in the field of biology. Functionalized quantum materials can be useful for biological sensing, therapeutics, and high-resolution cellular imaging when they have the right ligands, the speaker added.
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