Chemistry Nobel Prize 2023

Why in the News?

The 2023 Nobel Prize in Chemistry has been awarded to Moungi G. Bawendi, Louis E. Brus and Alexei I. Ekimov “for the discovery and synthesis of quantum dots” and have been lauded as pioneers in the exploration of the nanoworld.

Work of the Awardees:

1. In 1980s, Louis Brus and Alexei Ekimov succeeded independently creating quantum dots, which are nanoparticles so tiny that quantum effects determine their characteristics.
2. In 1993, laureate Moungi Bawendi revolutionised the methods for manufacturing quantum dots, making their quality extremely high – a vital prerequisite for their use in today’s nanotechnology.

Quantum dots:

1. Usually, every element exhibits specific properties which will be same regardless of its size. This form one of the fundamental facts of chemistry.

• For instance, a piece of pure gold, whether it is a large 100-gram piece or a small 10 milligram one, has exactly the same properties.

2. However, very small particles, in the nanoscale range (1 to 100 billionth of a metre) behave slightly differently from larger particles of the same element. 
3. Alexei Ekimov was the first to notice this deviant behaviour in Copper Chloride nanoparticles around 1980, and manufacture these nanoparticles to show this change in behaviour.
4. Louis Brus, an American scientist working independently, discovered similar behaviour in Cadmium Sulphide nanoparticles.
5. The deviant behaviour of small nanoparticles arises because of the emergence of quantum effects.
6. The quantum theory explains that, usually, electrons move around in a large empty space, relatively, outside the nucleus of the atom but when the size of the particles is reduced drastically, electrons in the atoms find themselves increasingly squeezed giving rise to the strange quantum effects.
7. Such strange effects and special properties were found in nanoparticles and hence were called quantum dots.

The discoveries:

1. When nanoparticles interact with light, the colour of any material depends on the wavelengths of the light spectrum absorbed or reflected by the material.
2. This led to the conclusion that number of electrons, the properties of the material were also being dictated by its size.

Applications:

In future, quantum dots can contribute to flexible electronics, miniscule sensors, slimmer solar cells and perhaps encrypted quantum communication.