Messenger Spectroscopy of C60 analogues

Since the discovery of the Buckminsterfullerene C60 in 1985, it has been speculated that these molecules could exist in space due to their exceptional stability and the high carbon content in space. This speculation was confirmed in 2010 when C 60 and C70 were identified in the infrared spectrum of the planetary nebula Tc1. This sparked the scientific community`s interest in their potential role as carriers of diffuse interstellar bands (DIBs). These bands are lines in the spectrum of stars caused by the absorption of light by interstellar dust. The exact identity of the molecules causing these bands, and thus the chemical composition of interstellar dust, has remained a major puzzle. So far, only the ionized fullerene C 60+ has been identified as a carrier, with its absorption spectrum measured in the laboratory under conditions mimicking those in space and compared with astronomical observations. Many other carbon-based molecules as well as fullerene derivatives are considered promising candidates for explaining additional DIBs but have not yet been studied in the laboratory at UV- and visible wavelengths due to technical challenges. A newly developed experimental setup at the University of Innsbruck now offers the possibility to conduct such measurements. This innovative setup, realized as part of a previous Hertha-Firnberg-Project, is considered a pioneer of modern laser spectroscopy in the cold gas phase. It allows molecules and larger complexes thereof to be embedded in the cold environment of helium nanodroplets (at temperatures below one Kelvin) and their absorption spectra to be measured in the UV-, visible-, and infrared wavelength range. As part of the project, this novel setup will be used to spectroscopically investigate singly and multiply charged complexes of C60 and other elements commonly found in space, such as hydrogen, carbon, iron, and magnesium. The absorption spectra will be compared with astronomical data to identify new carriers of DIBs or to rule out potential candidates. The project will provide important insights into our understanding of the cosmos and shed new light on the formation and evolution of galaxies.