A recent study led by space chemist Jordy Bouwman from CU Boulder provides insights into the formation of organic molecules in space, particularly buckminsterfullerene, commonly known as the “buckyball.” This spherical carbon molecule, resembling a soccer ball, is part of a broader investigation into the chemistry of the interstellar medium.
In the vast regions between stars, a rich assortment of carbon can be found, including a variety of organic molecules such as polycyclic aromatic hydrocarbons (PAHs) and buckyballs. The research team conducted experiments on Earth to simulate the conditions of space, potentially revealing crucial processes that influence the evolution of these organic compounds over time.
Bouwman emphasized the importance of understanding how carbon in the universe transforms into the building blocks of planetary systems, including our own solar system. He stated, “We”re all made of carbon, so it”s really important to know how carbon in the universe gets transformed on its way to being incorporated in a planetary system like our own solar system.”
The findings, published in the Journal of the American Chemical Society, focus on fullerenes, which consist of carbon atoms arranged in a closed-cage structure. The most notable example is the buckyball, composed of 60 carbon atoms.
Despite their presence in the interstellar medium, the origins and formation methods of fullerenes have long puzzled scientists. The new research indicates that radiation in space may facilitate the transformation of PAHs into fullerenes, suggesting a connection between these large aromatic molecules and the buckyballs found in space.
To investigate these chemical processes, the researchers examined two small PAH molecules, anthracene and phenanthrene. PAHs, structured like honeycombs, are prevalent on Earth in substances such as smoke and soot. Bouwman illustrated their presence by commenting, “If you put your steak on the grill for too long, and it gets black, that contains PAHs.”
In their experiments, the team bombarded these PAHs with electron beams, mimicking the effects of radiation in space. This exposure resulted in the formation of new, charged organic molecules. The products were then analyzed using an ion trap apparatus at the Free Electron Lasers for Infrared eXperiments (FELIX), a unique research facility in the Netherlands.
The results surprised the researchers. When anthracene and phenanthrene were bombarded with electrons, they lost hydrogen atoms, leading to a radical restructuring of the molecules. Instead of solely hexagonal arrangements, the new structures featured both hexagons and pentagons, akin to the shape of a soccer ball.
Co-author Sandra Brünken, an associate professor at Radboud University, remarked on the unexpected nature of these findings, stating, “That was a very surprising result—that just by kicking off a hydrogen atom or two, the entire molecule completely rearranged.” This transformation suggests that pentagon-bearing molecules could serve as a bridge in the conversion of common PAHs into fullerenes.
Bouwman and Brünken hope that their findings will inspire astrophysicists to search for similar pentagon-containing molecules in the depths of space, using advanced tools such as the James Webb Space Telescope. Brünken noted, “You can take our results from the laboratory, and then use them as a fingerprint to look for the same signatures in space.”
The study”s co-authors also include graduate students from LASP and scientists from other institutions including Radboud University, Leiden University, Paris-East Créteil University, and the University of Maryland College Park.
