The Astrophysical Journal (Jan 2023)

Buckyball-metal Complexes as Potential Carriers of Astronomical Unidentified Infrared Emission Bands

  • Gao-Lei Hou,
  • Olga V. Lushchikova,
  • Joost M. Bakker,
  • Peter Lievens,
  • Leen Decin,
  • Ewald Janssens

DOI
https://doi.org/10.3847/1538-4357/accf1b
Journal volume & issue
Vol. 952, no. 1
p. 13

Abstract

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Efforts over 40 yr still leave the source of astronomical infrared emission bands largely unidentified. Here, we report the first laboratory infrared (6–25 μ m) spectra of gas-phase fullerene-metal complexes, [C _60 -Metal] ^+ (Metal = Fe, V) and show with density functional theory calculations that complexes of C _60 with cosmically abundant metals, including Li, Na, K, Mg, Ca, Al, V, and Fe, all have similar spectral patterns. Comparison with observational infrared spectra from several fullerene-rich planetary nebulae demonstrates a strong positive linear cross-correlation. The infrared features of [C _60 -Metal] ^+ coincide with four bands attributed earlier to neutral C _60 bands and in addition also with several bands unexplained to date. Abundance and collision theory estimates indicate that [C _60 -Metal] ^+ could plausibly form and survive in astrophysical environments. Hence, [C _60 -Metal] ^+ are proposed as promising carriers, in supplement to C _60 , of observational bands, potentially representing the largest molecular species in space other than C _60 , C _60 ^+ , and C _70 .

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