Experimental Determination of the Unusual CH Stretch Frequency of Protonated Fullerenes

Laura Finazzi; Vincent J. Esposito; Julianna Palotás; Jonathan Martens; Els Peeters; Jan Cami; Giel Berden; Jos Oomens

doi:10.3847/1538-4357/ad6302

The Astrophysical Journal (Jan 2024)

Experimental Determination of the Unusual CH Stretch Frequency of Protonated Fullerenes

Laura Finazzi,
Vincent J. Esposito,
Julianna Palotás,
Jonathan Martens,
Els Peeters,
Jan Cami,
Giel Berden,
Jos Oomens

Affiliations

Laura Finazzi: ORCiD; Radboud University , Institute for Molecules and Materials, FELIX Laboratory, Nijmegen, The Netherlands ; [email protected]
Vincent J. Esposito: ORCiD; NASA Ames Research Center , Moffett Field, USA
Julianna Palotás: ORCiD; School of Chemistry, University of Edinburgh , Edinburgh, UK
Jonathan Martens: ORCiD; Radboud University , Institute for Molecules and Materials, FELIX Laboratory, Nijmegen, The Netherlands ; [email protected]
Els Peeters: ORCiD; Department of Physics and Astronomy, University of Western Ontario , London, ON N6A 3K7, Canada; Institute for Earth and Space Exploration, University of Western Ontario , London, ON N6A 3K7, Canada; SETI Institute , 189 Bernardo Ave, Suite 100, Mountain View, CA 94043, USA
Jan Cami: ORCiD; Department of Physics and Astronomy, University of Western Ontario , London, ON N6A 3K7, Canada; Institute for Earth and Space Exploration, University of Western Ontario , London, ON N6A 3K7, Canada; SETI Institute , 189 Bernardo Ave, Suite 100, Mountain View, CA 94043, USA
Giel Berden: ORCiD; Radboud University , Institute for Molecules and Materials, FELIX Laboratory, Nijmegen, The Netherlands ; [email protected]
Jos Oomens: ORCiD; Radboud University , Institute for Molecules and Materials, FELIX Laboratory, Nijmegen, The Netherlands ; [email protected]; van ’t Hoff Institute for Molecular Sciences, University of Amsterdam , Amsterdam, The Netherlands

DOI: https://doi.org/10.3847/1538-4357/ad6302
Journal volume & issue: Vol. 971, no. 2
p. 168

Abstract

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We report experimental values for the CH stretch frequencies of the protonated fullerenes C _60 H ^+ and C _70 H ^+ . Anharmonic frequency calculations at the B3LYP/6-31G level of theory, which are independent of empirical scaling factors, reproduce the experimental values to within approximately 5 cm ^−1 . Scaling theoretical harmonic frequencies by applying factors derived for polycyclic aromatic hydrocarbons deviate significantly from the experimentally measured frequency. We attribute this deviation to the unusual hydrocarbon structure that affects the degree of anharmonicity of the CH stretch. This result allows us to propose an original, specific scaling factor of 0.9524 to correct harmonic frequencies of CH stretches of protonated fullerenes calculated at the B3LYP/6-311 + G(d,p) level of theory. The special spectral position of the protonated fullerene CH stretch bands makes it a diagnostic marker that may aid in their detection in the interstellar medium.

Published in The Astrophysical Journal

ISSN: 1538-4357 (Online)
Publisher: IOP Publishing
Country of publisher: United Kingdom
LCC subjects: Science: Astronomy: Astrophysics
Website: https://iopscience.iop.org/journal/0004-637X

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