You may make fun, those silly stock photos of people in white coats pouring things into test tubes is actually what most people think when they hear “chemistry”. And it isn’t a wrong idea. You mix some chemicals with some other chemicals, and you get molecules – multiple atoms bonded together.
The scientists manipulated single atoms from a cloud of many using lasers to create a molecule. Image: Lee Liu
But a lab at Harvard is trying to add more precision to this process by bonding together just two individual atoms. They think that with further advancements, they could use this system to create more complex designer molecules.
“This the first time that we’ve been able to take exactly one atom and another atom of another species and combine them in a molecule, isolated,” said Lee Liu, a Harvard graduate student. “Some have been able to do them on surfaces, but we do it with no other things to interfere.”
The physics here isn’t too hard to understand. Scientists have long been able to push around single atoms within clouds of many atoms. In this case, they used two optical “tweezers” at two specific wavelengths. Basically, this is two differently-coloured lasers focused with a lens so that each laser controls one of two separate atoms, one cesium (Cs) and one sodium (Na) atom. They’re held still at near absolute zero in a vacuum. The researchers then overlap the beams to trap both atoms.
The researchers then excited the atoms with the energy from the laser and measured a “single instance of the chemical reaction” of the two atoms bonding to become NaCs, according to the paper published this week in Science. A single instance as in, it’s just two atoms making a single molecule, rather than many atoms making many molecules.
“The ability to allow to laser-cooled atoms to come together is an experimental tour de force,” Henry Rzepa, a chemist at Imperial College London in the UK, told Gizmodo. But as with any first, it’s worth being a little sceptical. Rzepa wasn’t quite convinced that there will be a future of creating multiple designer molecules in an isolated environment was a bit of a stretch. “Whether it will lead to the flight of fancy above remains to be seen.”
But with a little bit more work, said Liu, maybe this type of molecule could be used as a qubit for quantum computing applications.
On the nearer term, perhaps we’ll soon see stock photos of people in white coats operating optical tweezers. Who knows.