The breakthrough in the scientific community has yet again been made by the Indian Institute of Science (IISc), Bangalore. The institution’s scientists have managed to make a revolutionary new discovery about Few-Electron Bubbles (FEBs) in Superfluid Helium Gas, a feat never before achieved. This news has sparked interest in the scientific and academic circles worldwide as it offers a unique perspective into understanding the properties of superfluid helium.
Understanding Helium
Helium is well known by its chemical symbol He and atomic number 2. It was first discovered on Earth by the British chemist Sir William Ramsay in 1895. This element stands out due to being colourless, odourless, tasteless, non-toxic, and inert. It is also a monatomic gas, sitting at the top of the noble gas group in the periodic table. Of all the elements, helium possesses the lowest boiling point.
Introduction to Electrons
All matter is composed of atoms which are basic units of chemical elements; for instance, hydrogen, helium or oxygen. Atoms themselves are constituted by three particles: Protons, Neutrons and Electrons. Electrons are the subatomic particles that orbit the atom’s nucleus and generally carry a negative charge. They are significantly smaller than the nucleus of the atom.
Electron Bubble Phenomenon
An electron bubble refers to the vacant space around a free electron in a cryogenic gas or liquid such as neon or helium. These bubbles are typically minuscule, with about 2 nm in diameter at an atmospheric pressure. When an electron is injected into a superfluid form of helium, a Single Electron Bubble (SEB) is created. This cavity does not contain helium atoms but only the electron. The bubble shape depends on the electron’s energy state. For example, if the electron is in the ground state, or the state of lowest energy, the bubble will be spherical. There are also multiple electron bubbles, housing thousands of electrons.
Exotic Behaviour: Superfluidity
Superfluidity is a phenomenon witnessed in liquid helium near absolute zero temperatures (−273.15 °C), leading to frictionless flow and other peculiar behaviours. This frictionless behaviour is also noticed in superconducting solid electrons. In both cases, these unique behaviours spring from quantum mechanical effects.
Few-Electron Bubbles: A New Discovery
Few-Electron Bubbles, or FEBs, differ from their single counterparts in that they are nanometre-sized cavities in liquid helium that contain more than one but only a few free electrons. The number, state and interactions between these free electrons govern the physical and chemical properties of materials. These FEBs offer an intriguing system with both electron-electron interaction and electron-surface interaction. Moreover, they have been found to be stable for at least 15 milliseconds, longer than typical quantum changes, making them a viable subject for researchers.
Significance of the Study of FEBs
FEBs can prove to be instrumental in the study of how the energy states of electrons and interactions between them in a material influence its properties. They also hold the potential to unravel several phenomena such as turbulent flows in superfluids and viscous fluids, or the flow of heat in superfluid helium. Similar to how current flows without resistance in superconducting materials at extremely low temperatures, superfluid helium also conducts heat efficiently at very low temperatures. Consequently, the recent findings by the scientists at IISc are extensively valuable and hold a lot of promise for future research and studies.
