Physicists solve a 50-year mystery about a critically important molecule

tomwt — Wed, 02 Jul 2025 18:30:37 +0000

Physicists solve a 50-year mystery about a critically important molecule tomwt Wed, 07/02/2025 - 11:30 More CNAS in the Media Gayoung Lee | Gizmodo July 02, 2025

GIZMODO - After relying on an educated guess for decades, scientists have finally confirmed the dipole moment of aluminum monochloride (AlCl), an elusive but important molecule known to sneak around the interiors of ancient galaxies.

An electric dipole moment is a measure of polarity—a crucial determinant for many physical properties of any system, such as its boiling point or solubility. Given its importance, the new result, published last month in Physical Review A, presents exciting opportunities for applications across a wide range of fields, from quantum computing to astrophysics.

At our core, we’re all made of molecules. Anything we do—whether it’s picking up a cup of coffee or digesting coffee after taking a sip—can be explained in terms of molecular interactions. This is of obvious interest to scientists, and for a host of reasons. For one, knowing how different molecules interact either with each other or with their environment can reveal a lot about their respective characteristics, akin to how physicists study different particles using large particle colliders.

But another reason is that the interaction itself—in this case, the dipole moment—helps scientists understand completely different systems in unexpected ways. “In chemistry, dipole moments affect everything from bonding behavior to solvent interactions,” said Boerge Hemmerling, a physicist at the University of California (UC), Riverside, and paper co-author, in a statement. “In biology, they influence phenomena like hydrogen bonding in water. In physics and astronomy, the dipole moments can be harnessed to make neighboring molecules interact, for instance, with the goal to create a quantum entanglement between them.”

The dipole moment of AlCl, in particular, shows promise across a wide range of applications, added Stephen Kane, an astrophysicist at UC Riverside and study co-author, in the same statement. “Accurate dipole moment data improves how we interpret molecular signatures in starlight,” said Kane. “The ratio of aluminum to chlorine in stars, as revealed through AlCl measurements, provides critical clues to stellar nucleosynthesis and the material history of these celestial bodies.”

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