Chemistry requires effort. Whether it’s raising the temperature, making the atoms more likely to meet in a hot collision, or turning up the pressure and compressing them, building molecules generally requires some cost of energy.
Quantum theory provides a solution if you are patient. A team of researchers from the University of Innsbruck in Austria finally saw quantum tunneling in action in the world’s first experiment to measure the fusion of deuterium ions with hydrogen molecules.
A tunnel is a strangeness in the quantum universe that makes it seem like particles can pass through obstacles that would normally be difficult to overcome.
In chemistry, this obstacle is the energy needed for atoms to communicate with each other or with existing molecules.
However, the theory goes that in extremely rare cases, it is possible for nearby atoms to force their way through this energy barrier and effortlessly connect.
“Quantum mechanics allows particles to pass through the energy barrier due to their quantum mechanical wave properties, and interaction occurs.” He says first author Robert Wilde, an experimental physicist at the University of Innsbruck.
Quantum waves are the ghosts that drive the behavior of things like electrons, photons, and even entire groups of atoms, blurring their existence before any observation so they don’t sit in a specific place but rather occupy a continuum of possible positions.
This attenuation is not significant for larger objects like particles, cats, and galaxies. But as we get closer to individual subatomic particles, the range of possibilities widens, forcing the site states of the various quantum waves to overlap.
When that happens, the particles have little chance of appearing where they don’t have a job, or tunneling into areas that would require a large amount of force to enter.
One such area of an electron might be within the bonding region of a chemical reaction, where it bonds neighboring atoms and molecules together without breaking up under heat or pressure.
Understanding the role that quantum tunneling plays in the construction and rearrangement of molecules could have important implications for calculations of the release of energy in nuclear reactions, such as those involving hydrogen in stars and fusion reactors here on Earth.
while We have modeled this phenomenon For examples involving reactions between a negatively charged form of deuterium, an isotope of hydrogen containing a neutron, and dihydrogen, or H2, Proving the numbers experimentally requires a difficult level of precision.
To achieve this, Wilde and his colleagues cooled the negative deuterium ions to a temperature that stopped them before introducing a gas made of hydrogen molecules.
Without heat, the probability that a deuterium ion would gain the energy needed to force the hydrogen molecules to rearrange the atoms was much lower. However, it also forced the particles to sit quietly closer together, giving them more time to join together through the tunnels.
“In our experiment, we give the potential reactions in the trap about 15 minutes and then we determine the number of hydrogen ions formed. From their number, we can deduce how often the reaction will occur.” Wilde explains.
This number is just over 5 x 10-20 Reactions per second occurring per cubic centimeter, or about one tunneling event per hundred billion collisions. So not a lot. Although past modeling is supported by experience, it confirms a judgment that can be used in predictions elsewhere.
Since tunnels play quite a role in a variety of nuclear and chemical reactions, many of which can also occur in the frigid depths of space, having a good handle on the factors at play gives us a more solid basis for deciding. Our expectations are on.
This research has been published in Nature.https://www.nature.com/articles/s41586-023-05727-z