A completely new kind of molecule has been made by combining an extremely cold ion and a super-sized atom. The unusual molecular bond between the two particles was thousands of times longer than those in most room-temperature molecules, and the method to make and study it could kick-start a new branch of ultracold quantum chemistry.
Molecules form when atoms or groups of atoms share electrons or stick together because they are caught in each other鈥檚 electric fields. at the University of Stuttgart in Germany and his colleagues have now created giant ultracold molecules using two kinds of rubidium atoms: one with an electric charge and the other super-sized.
The researchers started with a cloud of rubidium atoms cooled to a millionth of a degree Celsius above absolute zero. They then used a laser beam to remove an electron from a single rubidium atom, which turned it into a positively charged ion.
Advertisement
Next, they used another laser to add energy to a different atom, which made its outermost electrons move far from the nucleus and stretch the whole atom out to an unusually large size.
Because these far-out electrons are extremely sensitive to the presence of electric charges, the giant atom couldn鈥檛 escape the influence of the ion. The two became bound in a molecule roughly 4 micrometres long, a few times bigger than some bacteria and a hundred times larger than a carbon dioxide molecule.
Each such molecule, and the molecular bonds that keep it together, are the first of their kind, says at Ulm University in Germany, who wasn鈥檛 involved in the experiment. 鈥淚n chemistry, we learn that there are a handful of binding mechanisms which are responsible for the structure of the material world around us. But, of course, our world is much richer,鈥� he says. 鈥淚t is exciting to find novel ways for making chemical bonds.鈥�
To observe the quantum processes that only occur between extremely cold atoms and ions, Pfau and his team had to design a special microscope. They spent four years developing their so-called ionic microscope, which applies an electric field to the new molecules to make them fly onto a detector. This allowed the researchers to confirm the formation of the new type of molecular bond.
at Harvard University says that being able to create new molecules and study them with the ionic microscope may lead to research in a previous unexplored type of ultracold quantum chemistry. Researchers had theoretical ideas about doing so in the past, but the new experiment demonstrated fantastic tools for actually making it happen, he says.
Nature
