Observed for the First Time
Atomic Rainbow in Graphene
- 10.08.2026
Sometimes, you just have to look closely enough – and a rainbow appears. A research team from the University of Duisburg-Essen and Uppsala University has now experimentally observed such a phenomenon at the atomic scale for the first time. The first author of the study, published in the journal Carbon, is physicist Carolin Frank, who is pursuing her doctorate at both universities.
Graphene consists of a single layer of carbon atoms arranged in a hexagonal honeycomb lattice. This makes the material an ideal test system. For the experiment, the team accelerated xenon ions to an energy of 40 kiloelectronvolts (40 keV) and transmitted them through free-standing single-layer graphene. The tiny deflections of the particles produced a characteristic scattering pattern: a circular outer rainbow and a hexagonal inner rainbow. This phenomenon is known as rainbow scattering and has now been experimentally observed in ion transmission through single-layer graphene for the first time.
“Only the combination of the ultraclean graphene sample from Duisburg and the exceptional resolution of the measurement system in Uppsala made this observation possible,” says Carolin Frank, a member of the research group led by experimental physicist Prof. Dr. Marika Schleberger at the University of Duisburg-Essen. “The scattering pattern is highly sensitive to even small amounts of surface contamination, which explains why it has not been reported before.”
Particularly revealing was the comparison of the experimental data with different computer simulations. While existing models reproduce the outer rainbow well, significant deviations emerge for the inner hexagonal pattern. The results reveal where commonly used models of ion-solid interactions reach their limits.
“Graphene serves not only as a target material, but also as a particularly sensitive testbed for models of ion-solid interactions,” says Prof. Dr. Marika Schleberger, co-author of the study. Because the material consists of only a single atomic layer, even subtle differences between experiment and theory can be detected.
In the future, the researchers plan to extend their approach to other ion species and different two-dimensional materials. This could provide more detailed insights into the fast processes governing the interactions of energetic charged particles with condensed matter and help to further improve theoretical models.
Picture:
Experimental physicist Carolin Frank
Further information:
https://www.sciencedirect.com/science/article/pii/S0008622326005208
Carolin Frank, Experimental Physics, carolin.frank@uni-due.de