In a breakthrough, researchers have discovered a new weak type of atomic bond and have confirmed the theory that predicted the bond 14 years ago. Physicists from the Purdue University in the US have for the first time ever observed butterfly Rydberg molecule which is a very strange molecule and a weak pairing of highly excitable atoms.
Rydberg molecules are super electronically excited as they are formed when an electron is sent far from atom’s nucleus. The phenomenon of formation of such molecules can occur on its own and it is pretty common. However, a team of researchers presented a theory that stated that Rydberg molecules can form a molecular bond which was thought impossible as the theory does not comply with our understanding of how atoms bind with other atoms.
They named the theory of hypothetical molecule combination as the butterfly Rydberg molecule. The molecular bond was named after seeing the butterfly-like distribution of the orbiting electrons. It took nearly 14 years for the same team to confirm the presence of the weak molecular bond.
“This new binding mechanism, in which an electron can grab and trap an atom, is really new from the point of view of chemistry,” explained lead researcher Chris Greene. “It’s a whole new way an atom can be bound by another atom.”
Researchers further explained that the Rydberg molecules are nearly 100-1000 times farther from nucleus when compared to normal molecules. For creating the bond, study authors first started with the Rubidium. They exposed Rubidium gas to a temperature of 100 nano-Kelvin — one ten-millionth of a degree above absolute zero and then used lasers to excite the atom to Rydberg state.
Physicist then kept the molecules under observation and started looking for any changes in the frequency of light absorbed by the molecules which would suggest that molecules have interacted and have made a bond. After years of observation, researchers were able to detect weak bond formation by the distant electrons.
“This [distant] electron is like a sheepdog,” said Greene. “Every time it whizzes past another atom, this Rydberg atom adds a little attraction and nudges it toward one spot until it captures and binds the two atoms together. It’s a really clear demonstration that this class of molecules exist,” he added.
The study appeared in the journal Nature Communications.