Spectroscopy of astrophysically relevant ions in traps

Abstract

The detection of molecules in the interstellar medium relies on the comparison between observational and laboratory data recorded under relevant conditions. In this contribution, the use of cryogenic ion traps to obtain low temperature spectra of gas-phase ions of astrophysical relevance is reviewed. By exploiting the unique properties of these devices, the requisite spectroscopic data that led to the identification of C + 60 as the first carrier of the enigmatic diffuse interstellar bands could be measured. These experiments are discussed, along with electronic transitions of other fullerenes, and recent approaches to synthesize and characterize molecular ions of long-held astrochemical interest.

Electronic Spectroscopy of Monocyclic Carbon Ring Cations for Astrochemical Consideration

“…To address this, approaches involving nonstandard methods for synthesis combined with cooling, and action spectroscopy in cryogenic traps have been recently applied. 21 …”

“…As a result, little spectroscopic data has been added to that compiled in the reviews in the 1990s by van Orden and Saykally, and Bowers and colleagues, in which this knowledge gap was highlighted. To address this, approaches involving nonstandard methods for synthesis combined with cooling, and action spectroscopy in cryogenic traps have been recently applied …”

“…To address this, approaches involving nonstandard methods for synthesis combined with cooling, and action spectroscopy in cryogenic traps have been recently applied. 21 An instrument was constructed in our laboratory to combine laser vaporization synthesis with mass-selection and cryogenic ion trapping spectroscopy, and proof-of-principle results on helium tagged cyclic C 6 + were presented. 22 Various action spectroscopy methods were used to detect the 2 Π g ← X 2 Σ u + electronic transition of linear C 5 + .…”

Metallofullerenes as potential candidates for the explanation of astrophysical phenomena

“…Moreover, they found that the complexation of metals with fullerenes could lead to a far richer spectrum in the visible and near-infrared spectral range than fullerenes themselves, due to the charge transfer from the metal to the carbon cage, making them potential candidates for diffuse interstellar bands (DIBs). 59 The recent findings performed by Campbell et al , 60,61 about the synthesis of C 60 + ions tagged with helium and its UV-visible spectrum measurement, show experimental possibility that would support the speculations by Hou et al 19 about the charge transfer process of metallofullerenes and their contribution to the visible regime. Metals are widely known to be active catalysts for the synthetic production of various carbon nanostructures, including carbon cages under oxygen- and hydrogen-rich conditions as found by Dunk et al 38,41 Then, one may speculate from the study of Hou et al 19 that metal atoms and their ions might also play a catalytic role in fullerene formation in space, as metallofullerenes, if present, could be considered as byproducts of this catalytic process.…”

Photofragmentation of corannulene (C20H10) and sumanene (C21H12) cations in the gas phase and their astrophysical implications

“…Besides PAHs, buckminsterfullerene, C 60 , has also been identified in the ISM through its infrared bands using the Spitzer Space Telescope, 6 and this was confirmed through its electronic transitions in the far-red. 7,8 It is found that, close to stars, the abundance of C 60 increases rapidly while the abundance of PAHs decreases away from stars. 9,10 This has been attributed to photochemical fragmentation and isomerization processes under the influence of the strong stellar ultraviolet (UV) radiation field but the details of these processes are not yet understood.…”