Abstract
The assignment of several diffuse interstellar bands in the near-infrared to C60+ ions present at high abundance in space has renewed interest in the astrochemical importance of fullerenes and analogues. Many of the latter have not been produced in macroscopic quantities, and their spectroscopic properties are not available for comparison with astronomical observations. An apparatus has been constructed that combines laser vaporisation synthesis with spectroscopic characterisation at low temperature in a cryogenic trap. This instrument is used here to record the electronic absorptions of C60+ produced by laser vaporisation of graphite. These are detected by (helium tagged) messenger spectroscopy in a cryogenic trap. By comparison with spectra obtained using a sublimed sample of Buckminsterfullerene, the observed data show that this isomer is the dominant C60+ structure tagged with helium at m/z=724, indicating that the adopted approach can be used to access the spectra of other fullerenes and derivatives of astrochemical interest.
Highlights
The discovery of fullerenes in 1985 resulted from attempts to simulate circumstellar conditions to see whether they promote the formation of long carbon-chain molecules detected by radioastronomy in dense clouds [1]
Buffer gas cooling and spectroscopic characterisation in a cryogenic ion trap have been used to demonstrate the formation of the Buckminsterfullerene cation C60 by laser vaporisation of graphite
The Bg ← X Au and Ag ← X Au electronic band origins near 10,378 and 10,438 cm−1 were detected by messenger spectroscopy, and found to be consistent with results of experiments using a sublimed sample of C60, indicating that of the C60 ions tagged with helium in the trap (m/z = 724), the D5d /C2h soccer ball isomer dominates
Summary
The discovery of fullerenes in 1985 resulted from attempts to simulate circumstellar conditions to see whether they promote the formation of long carbon-chain molecules detected by radioastronomy in dense clouds [1]. In the context of their electronic transitions and the DIBs, fullerene analogues containing cosmically abundant atoms have long aroused interest [25] Evaluation of their astrochemical significance, awaits measurement of their spectroscopic properties in the gas phase at low temperature, which is necessary for direct comparison with observational data in the visible. In the ion trap study, number densities of helium buffer gas of 4 × 1015 cm−3 coupled with an interaction time of >500 ms led to millions of collisions with cryogenic helium This technique was exploited to prepare C60 ions for spectroscopic characterisation, leading to its confirmation as the carrier of the 9577 and 9632 Å DIBs [9].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
