Electronic Transitions Responsible for C60+ Diffuse Interstellar Bands
Aleksandr O Lykhin1, Seyedsaeid Ahmadvand1, Sergey A Varganov1
1Department of Chemistry , University of Nevada, Reno , 1664 North Virginia Street , Reno , Nevada 89557-0216 , United States.
The Journal of Physical Chemistry Letters
|December 19, 2018
Summary
Fullerenes like C60+ are confirmed carriers of diffuse interstellar bands (DIBs). This study reveals their transitions originate from non-Franck-Condon regions and vibronic excitations, not simple electronic states.
Area of Science:
- Astrochemistry
- Quantum Chemistry
- Spectroscopy
Background:
- Diffuse interstellar bands (DIBs) are unexplained absorption features in space.
- C60+ (buckminsterfullerene cation) is the first confirmed carrier of several DIBs.
- The specific electronic transitions responsible for C60+ DIBs remain unclear.
Purpose of the Study:
- To elucidate the nature of electronic transitions in C60+ responsible for observed DIBs.
- To investigate the role of Jahn-Teller distortion and vibronic coupling in C60+ DIBs.
- To accurately assign specific DIB wavelengths to C60+ transitions.
Main Methods:
- Utilized advanced electronic structure calculations.
- Simulated transitions to excited electronic states of C60+.
- Analyzed the influence of Jahn-Teller distortion and vibronic interactions.
Main Results:
- Ruled out simple electronic transitions to excited 2E1g states or spin-orbit components.
- Attributed strong DIBs (9632, 9577 Å) to cold excitations from the ground state's non-Franck-Condon region.
- Assigned weak DIBs (9428, 9365 Å) to vibronic transitions involving low-energy modes.
Conclusions:
- The observed C60+ DIBs are explained by complex excitations beyond simple electronic transitions.
- Jahn-Teller distortion and vibronic coupling are crucial for understanding C60+ DIB spectra.
- This work provides a framework for interpreting DIBs from molecular carriers.
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