New tools to fathom the world of electrons

Why in the News?

Recently Pierre Agostini, Ferenc Krausz and Anne L’Huillier have been awarded Nobel Prize in physics, 2023 for their contribution to making it possible to watch electrons move using experimental methods that generate attosecond pulses of light.

What is an attosecond?

1. An attosecond is one quintillionth of a second, or 10^-18 seconds.
2. An attosecond is the timescale at which the properties of an electron change, which makes it possible to study and truly understand electrons.

What is attosecond science?

1. Attosecond science deals with the production of extremely short light pulses to study superfast processes.
2. For instance, a hummingbird’s wings beat 80 times a second with each beat lasting 1/80th of a second, which is difficult for human eyes to capture (human eye can see up to 60 frames per second at its best).
3. The solution can involve the use of digital camera that creates photographs by capturing light coming from a source using a sensor. It can be done on 2 ways:
   1. The aperture can be opened for exactly 1/80th of a second to capture the reflection.
   2. Alternatively, aperture can be kept open at all times and release a light pulse whose duration is 1/80th of a second towards the wing and capture the reflection. This is a better option to study electrons.

Significance of their work:

1. Atoms or molecules make movements, or changes took place generally in picoseconds (10^-12) or femtoseconds (10^-15), which required unimaginably short pulses of light to capture their movement. For that femtosecond ‘photography’ was developed and was considered the limit.
2. However, there were processes that were even faster in atoms happening within a few attoseconds (10^-18).
3. Pierre Agostini, Ferenc Krausz and Anne L’Huillier worked
   1. Anne L’Huillier, 1988 witnessed the phenomenon of high-harmonic generation i.e., when a beam of infrared light is passed through a noble gas, the gas emitted light whose frequency was a high multiple of the beam’s frequency with a sharply declining light intensity and then plateaued and again declined.
   2. Later in 1994, A beam of light consists of oscillating electric and magnetic fields was imparted to electrons:
      1. The oscillating field would impart some energy to the electron and then take away from it.
      2. when energy is imparted, the electron would come loose from an atom, and when it is taken away, the electron and the atom would recombine, releasing some excess energy. This energy is the light re-emitted by the gas.
   3. They developed experimental methods that generate attosecond pulses of light for the study of electron dynamics in matter.
   4. They 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.
   5. RABBIT technique:
      1. A major technique to measure the duration of a short light pulse was developed by Pierre Agostini and his colleagues in 1994.
4. The sub-atomic motion happens in a matter of attoseconds.

• For instance, the dynamics of the electron are 100 to 1,000 times faster than that of the atom. This is because atom is heavier, because of the nucleus, and has greater inertia (Lower the inertia, faster the dynamics).

5. They mixed the lights of different wavelengths, to produce attosecond pulses.
6. Challenges in developing attosecond light pulses:
   1. To capture a process, the measurement must be made at a pace quicker than the rate of change.
   2. But, for all sorts of light produced by laser systems, this cycle used to take at least a few femtoseconds to complete.
7. Possible applications:
   1. It has potential applications in a variety of areas, from electronics to medicine, across disciplines in physics, chemistry and biology.
   2. In medical science, particularly in finding therapies for cancer care.
   3. Study molecular-level changes in blood, to identify diseases.
   4. Create more efficient electronic gadgets by better understanding of how electrons move and transmit energy.