The Unforeseen Dynamics of Ionized Carbon Dioxide Dimers

An exciting breakthrough in molecular physics has been made by an international team of scientists, led by Profs. Daniel Strasser and Roi Baer from The Hebrew University of Jerusalem. Their research has uncovered unexpected symmetry-breaking dynamics in ionized carbon dioxide dimers, shedding light on structural changes induced by extreme ultraviolet (EUV) radiation. This groundbreaking study, titled “Symmetry-breaking dynamics of a photoionized carbon dioxide dimer,” is now published in Nature Communications.

In environments like cold outer space and atmospheric settings, carbon dioxide molecules typically form symmetrically shaped pairs. According to quantum mechanics, the wave function of these pairs should maintain symmetry even after ionization. However, the collaborative team from The Hebrew University of Jerusalem, the Max Planck Institute for Nuclear Physics, and the FLASH free electron laser facility at DESY observed a phenomenon called symmetry-breaking. It defied the expectations of two well-established quantum chemistry models used to predict the behavior of ionized dimers.

While one model proposed that the ionized molecules would move in unison, preserving their symmetrical shape, the other model predicted that symmetry would be broken. The latter scenario was confirmed through the use of ultrafast EUV pulses generated by the FLASH free electron laser. The researchers observed that the ionized dimers indeed undergo asymmetric structural rearrangement, leading to the formation of CO3 moieties. This finding offers valuable insights into the behavior of molecules under extreme conditions, with potential implications for atmospheric and astrochemistry.

Despite quantum mechanics prohibiting symmetry-breaking, the researchers explain the phenomenon using the analogy of Schrödinger’s famous cat. The pair of carbon dioxide molecules exists in a superposition of two symmetry-breaking states until the quantum wave function collapses upon measurement. This results in one of the CO2 molecules rotating relative to the other, highlighting the complex interplay of quantum dynamics in molecular systems.

Prof. Strasser emphasized the importance of combining cutting-edge experimental techniques with advanced theoretical modeling to uncover unexpected molecular behavior. The study’s results not only deepen our understanding of ionized carbon dioxide dimers but also have broader implications for carbon dioxide chemistry and planetary atmospheric processes. Prof. Baer, who led the theoretical modeling, highlighted the impact of directly comparing theory with experimental measurements in improving our ability to simulate and predict chemical reactions in remote environments.

The discovery of asymmetric structural rearrangements and CO3 moiety formation in ionized carbon dioxide dimers opens up new possibilities for studying molecular processes under extreme conditions. This research has significant implications for atmospheric chemistry, astrochemistry, and the understanding of the atmospheric carbon dioxide cycle. Through international collaboration and state-of-the-art facilities like the FLASH2 free electron laser at DESY, the team’s innovative approach sets the stage for further investigations into molecular cluster behavior under extreme conditions. The implications of this research span from atmospheric science to the development of novel chemical synthesis methods.