The Optical Spectrum Of The Diamantane Radical Cation

Crandall, Parker B.

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https://hdl.handle.net/2142/116771 Copy

Description

Title

The Optical Spectrum Of The Diamantane Radical Cation

Author(s)

Crandall, Parker B.

Contributor(s)

• Dopfer, Otto
• Förstel, Marko
• Radloff, Robert G.

Issue Date

2022-06-23

Keyword(s)

Astronomy

Abstract

Diamondoids are a class of stable, aliphatic molecules arranged in cage-like structures and serve as a link between small, cyclic hydrocarbons and bulk nanodiamonds. Similarities have been observed between the infrared spectra of diamondoids and unidentified infrared emission bands seen in the spectra of young stars with circumstellar disks.$^{1}$ It is also suggested that the radical cations of these molecules could contribute to features in the well-known but largely unassigned diffuse interstellar bands due to their low ionization energy and absorption in the visible range.$^{2}$ However, only the optical spectrum of the adamantane cation has been measured so far.$^{3}$ Herein, we report the first optical spectrum of the diamantane radical cation (\chem{C_{14}H_{20}^+}) between 400 and 1000 nm in the gas phase. Measurements were taken in a tandem mass spectrometer by photodissociation of mass-selected ions cooled in a cryogenic 22-pole ion trap held at 5 K. The optical spectrum reveals two broad and unresolved bands centered near 760 and 450 nm that are assigned to the \chem{D_2(^2E_u)} $\leftarrow$ \chem{D_0(^2A_{1g})} and \chem{D_5(^2A_{2u})} $\leftarrow$ \chem{D_0(^2A_{1g})} transitions using time-dependent density function theory calculations. These calculations also assist to explain the lack of vibrational structure as the result of lifetime broadening and Franck-Condon congestion arising from large geometry changes.\\ \noindent Literature:\\ \noindent $^{1}$O. Pirali, M. Vervloet, J. E. Dahl, R. M. K. Carlson, A. G. G. M. Tielens, J. Oomens, Astrophys. J., 661, 919–925 (2007).\\ \noindent $^{2}$M. Steglich, F. Huisken, J. E. Dahl, R. M. K. Carlson, T. Henning, Astrophys. J., 729, 91–100 (2011). \\ \noindent $^{3}$P. B. Crandall, D. Müller, J. Leroux, M. Förstel and O. Dopfer, 2020, Astrophys. J. Letters, 900, L20

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Handle URL

https://hdl.handle.net/2142/116771

DOI

https://doi.org/10.15278/isms.2022.RN09

Copyright and License Information

Copyright 2022 held by the authors

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