Nobel 2023 Part II
Posted by on Wednesday, October 4, 2023
What an interesting year this has been for the Nobel Prizes!
As most of you know, I don't usually write about the Nobel Prize in Chemistry, because I am not a chemist by training. I have always been interested in chemistry, but my training and research is entirely in theoretical physics and mathematics. However this year is a bit of an exception for one simple reason - the Nobel Prize in Chemistry has been awarded for work that is closely related to quantum physics, which was always one of the subjects that I was interested in as a research physicist. (It is also interesting to me that this year the Nobel Prize for Chemistry is for work in quantum physics, while the Nobel Prize in Physics was for work whose practical applications are more focused on chemistry. Perhaps someone mixed up the envelopes :) )
This year the Nobel Prize in Chemistry has been awarded to Moungi Bawendi, Louis Brus and Alexei Ekimov for research into the creation and application of quantum dots. And while this might sound like something quite exotic and purely of academic interest, it is this work that has allowed for recent developments in coloured LEDs, flat screen televisions, and even medical imaging technologies that permit doctors to study blood vessels inside tumors.
The existence of quantum dots has been theorized almost since the development of modern quantum mechanics in the 1920s and 1930s, but their practical development in the laboratory and in industry are relatively recent achievements. And the three winners of the Nobel Prize were each independently responsible for parts of these advancements over the last forty years.
The earliest of these was Ekimov's work through the early 1980s, which the discovery that colour of glass actually varies depending on the size and quantity of clusters of copper chloride molecules contained in it, and the determination that it was inherently an effect of quantum mechanics. Then a few years later, Brus made similar ground-breaking discoveries while studying the colour of fluids. And the final recipient, Bawendi, then made a more technical breakthrough in 1993 by developing methods of using clusters of molecules, each containing between a few hundred and a few thousand atoms, to produce quantum dots reliably and on a larger and economical scale.
A full explanation of the science of quantum dots is beyond the scope of this article, but it can be summarized as follows:
When there is a cluster of atoms, the electrons contained within their orbitals can move between them. However the electrons cannot leave the cluster, and are constrained to certain orbits throughout the cluster. According to the laws of quantum mechanics, electrons in each of these orbits will have very specific energies which are unique to the size and composition of the cluster. And as anyone who has taken an introductory quantum physics course knows (or who even has watched a Youtube video on the subject), when electrons change energy levels (or switch orbits) they either absorb or emit light at very specific frequencies.
If the cluster is very large - such as millions of billions of atoms wide - then there are so many possible orbits and energy level transitions that all of the frequencies run together and we see a continuous range of colours. But in the case of nanoscale clusters, containing just a few thousand atoms at most, the energy transitions are more restricted. For these smaller clusters, light will be emitted in only specific frequencies, and thus the clusters will always absorb and emit light in a few (or even just one) characteristic colours.
By manufacturing such quantum dots of a specific size and composition, we can create solids and fluids that will glow with virtually any colour we wish to manufacture. If we use these quantum dots in semiconductor crystals, then we can create light emitting diodes that glow in a specific colour. This same method can be used to create display screens by combining different types of quantum dots to display all of the colours visible to the human eye. And being of nanoscale size, and usually inert, the quantum dots can even be injected into the human body to conduct medical studies and treatments by either causing them to glow, or by causing them to selectively absorb electromagnetic radiation that the surrounding tissues do not.
In truth, both the research uses and practical applications of quantum dots are endless, and are still the subject of research by thousands of groups around the world. We are just now beginning to enter the age of nanotechnology, and quantum dots are one of the technologies at the forefront of this growing field.
Congratulations to all of the people involved in this research, and especially to the three winners of the biggest prize in chemistry. It is indeed a very important achievement, and definitely worth of the 2023 Nobel Prize in Chemistry.
As most of you know, I don't usually write about the Nobel Prize in Chemistry, because I am not a chemist by training. I have always been interested in chemistry, but my training and research is entirely in theoretical physics and mathematics. However this year is a bit of an exception for one simple reason - the Nobel Prize in Chemistry has been awarded for work that is closely related to quantum physics, which was always one of the subjects that I was interested in as a research physicist. (It is also interesting to me that this year the Nobel Prize for Chemistry is for work in quantum physics, while the Nobel Prize in Physics was for work whose practical applications are more focused on chemistry. Perhaps someone mixed up the envelopes :) )
This year the Nobel Prize in Chemistry has been awarded to Moungi Bawendi, Louis Brus and Alexei Ekimov for research into the creation and application of quantum dots. And while this might sound like something quite exotic and purely of academic interest, it is this work that has allowed for recent developments in coloured LEDs, flat screen televisions, and even medical imaging technologies that permit doctors to study blood vessels inside tumors.
The existence of quantum dots has been theorized almost since the development of modern quantum mechanics in the 1920s and 1930s, but their practical development in the laboratory and in industry are relatively recent achievements. And the three winners of the Nobel Prize were each independently responsible for parts of these advancements over the last forty years.
The earliest of these was Ekimov's work through the early 1980s, which the discovery that colour of glass actually varies depending on the size and quantity of clusters of copper chloride molecules contained in it, and the determination that it was inherently an effect of quantum mechanics. Then a few years later, Brus made similar ground-breaking discoveries while studying the colour of fluids. And the final recipient, Bawendi, then made a more technical breakthrough in 1993 by developing methods of using clusters of molecules, each containing between a few hundred and a few thousand atoms, to produce quantum dots reliably and on a larger and economical scale.
A full explanation of the science of quantum dots is beyond the scope of this article, but it can be summarized as follows:
When there is a cluster of atoms, the electrons contained within their orbitals can move between them. However the electrons cannot leave the cluster, and are constrained to certain orbits throughout the cluster. According to the laws of quantum mechanics, electrons in each of these orbits will have very specific energies which are unique to the size and composition of the cluster. And as anyone who has taken an introductory quantum physics course knows (or who even has watched a Youtube video on the subject), when electrons change energy levels (or switch orbits) they either absorb or emit light at very specific frequencies.
If the cluster is very large - such as millions of billions of atoms wide - then there are so many possible orbits and energy level transitions that all of the frequencies run together and we see a continuous range of colours. But in the case of nanoscale clusters, containing just a few thousand atoms at most, the energy transitions are more restricted. For these smaller clusters, light will be emitted in only specific frequencies, and thus the clusters will always absorb and emit light in a few (or even just one) characteristic colours.
By manufacturing such quantum dots of a specific size and composition, we can create solids and fluids that will glow with virtually any colour we wish to manufacture. If we use these quantum dots in semiconductor crystals, then we can create light emitting diodes that glow in a specific colour. This same method can be used to create display screens by combining different types of quantum dots to display all of the colours visible to the human eye. And being of nanoscale size, and usually inert, the quantum dots can even be injected into the human body to conduct medical studies and treatments by either causing them to glow, or by causing them to selectively absorb electromagnetic radiation that the surrounding tissues do not.
In truth, both the research uses and practical applications of quantum dots are endless, and are still the subject of research by thousands of groups around the world. We are just now beginning to enter the age of nanotechnology, and quantum dots are one of the technologies at the forefront of this growing field.
Congratulations to all of the people involved in this research, and especially to the three winners of the biggest prize in chemistry. It is indeed a very important achievement, and definitely worth of the 2023 Nobel Prize in Chemistry.
I am a theoretical physicist & mathematician, with training in electronics, programming, robotics, and a number of other related fields.
