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The Nobel Prize in Physics 2023 has been awarded to Pierre Agostini, Ferenc Krausz and Anne L’ Huillier for “experimental methods that generate attosecond pulses of light for the study of electron dynamics in matter”. With this, Anne L’ Huillier became only the fifth woman to win the Nobel Prize in Physics.
The generation of attosecond pulses to study electrons is fundamental research that gives information about the location and movement of electrons inside atoms and molecules. But applications in the field of medicine and semiconductor technology are in sight now.
“Pierre Agostini, Ferenc Krausz and Anne L’Huillier have demonstrated a way to create extremely short pulses of light that can be used to measure the rapid processes in which electrons move or change energy,” said the press release from the Nobel Committee.
Investigating events that occur at a fast pace such as in the case of electrons requires special technology. This is because the movements of electrons within atoms and molecules are happening at a few tenths of an attosecond and there are as many attoseconds in a second as there are seconds since the birth of the universe.
“If one divides the duration of a heartbeat by 1,000 five times continuously, we get to the timescale of atoms and then if we divide this time period by 1,000 again, we arrive at the timescale of electrons,” said Eva Olsson, chair of the Nobel Committee for Physics, at a press conference to announce the prize.
This year’s laureates discovered that it was possible to generate attosecond pulses which was thought to be quite impossible at the time of Werner Heisenberg who had postulated that one can never know the exact location and velocity of an electron simultaneously. This is known as the ‘Heisenberg Principle’ in Physics.
In 1987, L’Huillier conducted experiments in which she passed infrared laser light through a noble gas such as argon and discovered that many different overtones of light arise when the light wave interacts with the atoms of the gas.
Some electrons gain excess energy which gets emitted as an overtone. Each of these overtones is a wave of light with a definite frequency. L’Huillier has been studying this phenomenon ever since.
The other two scientists went on to develop methods and techniques to generate these extremely short pulses.
They were first demonstrated by Augustini in Paris in 2001 through his RABBIT technique and by Krausz in Vienna in the same year through his Streaking technique.
In these techniques they produced and investigated extremely short light pulses of 250 attoseconds (Augustini) and 650 attoseconds (Krausz).
“Our methods do not violate the Heisenberg principle. The picture of the electron we have is still quite blurry. But we are getting new information about the location and movement of the electrons by using these attosecond pulses. Applications are also now coming up,” said L’Huillier, answering a question at the press conference.
“We need to image an electron as a wave. We are looking at the position of the crest of that wave. From this we also get to know information about the time it takes for the electron to move,” added L’Huillier.
One of the applications of the technique could be in studying blood samples at the minutest levels and coming up with better ways to analyse it and diagnose for diseases like lung cancer. Another possible application is in the field of semiconductor technologies where it can be used as an imaging tool.
It may also be used to understand processes in nature that involve electron transport, the most important among which would be photosynthesis, L’Huillier pointed out.
Photosynthesis is the natural process that occurs in green plants and trees and converts the Sun’s light energy and carbon dioxide into glucose and oxygen. It is the primary source of nutrition for almost all of life on Earth.
On the fact that she is only the fifth woman to ever win the most coveted prize in Physics, L’Huillier said that “this is incredible as not many women have won the prize in the past. It is very special”.