Electron ionization of helium droplets containing C₆₀ and alcohol clusters

Abstract

aWe report a mass spectrometric investigation of (C 60 ) n clusters mixed with either methanol or ethanol clusters inside helium nanodroplets. The abundance of ion products produced by electron ionization shows marked differences compared with pure methanol/ethanol clusters without C 60 [M. Goulart, P. Bartl, A. Mauracher, F. Zappa, A. M. Ellis and P. Scheier, Phys. Chem. Chem. Phys., 2013, 15, 3577], where clusters containing in excess of a hundred alcohol monomers were observed. In contrast, under identical conditions concerning He droplet size and alcohol pickup pressure, only a small number of alcohol molecules become attached to the fullerene ions. Our results suggest that each fullerene cluster acts as a charge sink, which hampers alcohol cluster formation, as well as intra-cluster ion-molecule reactions. The appearance of specific 'magic number' peaks suggests an enhanced probability for the attachment of small alcohol rings to (C 60 ) n + clusters.

Electron attachment and electron ionization of helium droplets containing clusters of C60 and formic acid

“…However, methanol-water complexes were absent below the methanol heptamer whereas complexes of FA with water appear for any number of FA molecules. Furthermore, methanol-water complexes were relatively weak in the presence of C60 [53], contrary to our present results for FA-water. 4.…”

“…1. In previous work we have reported positive ion mass spectra of HNDs doped with C60 and other molecules that, in the absence of C60, tend to form hydrogenated cluster ions, including H2 [33,45,46], H2O [47,48], NH3 [49], CH4 [50,51], C2H4 [52], CH3OH, and CH5OH [53]; for a review see [54]. A comparison of our results for FA with other molecules that form hydrogen-bonded networks is most instructive.…”

Solvation of ions in helium

“…This is a simplified view but ab-initio Hartree-Fock calculations show that the Mulliken charge on a H 2 O molecule remains below 0.05e [259]. The Innsbruck group has reported analogous results for HNDs doped with C 60 or C 70 and H 2 , NH 3 , CH 4 , HCOOH, CH 3 OH or C 2 H 5 OH [219,254,255,260,261].…”

Chemistry and physics of dopants embedded in helium droplets

“…It was shown that despite fragmentation of molecular dopants not being quenched by energy dissipation, fragmentation intermediates can be stabilized within the He matrix (Bartl et al, 2013). EI and PI were used in the past to analyze the behavior of a variety of atomic and molecular dopants such as Au (Martini et al, 2018), haloalkanes (Yang et al, 2006), rare gases (Kim et al, 2006), SF 6 (Peterka et al, 2006), H 2 O (Yang et al, 2007), acetic acid (da Silva, Jaksch, et al, 2009), CH 4 (Leidlmair, Bartl, et al, 2012), NaF (Weinberger et al, 2016), valine (Weinberger et al, 2016), C 60 (Goulart et al, 2017), or formic acid (Mahmoodi‐Darian et al, 2019). For a more comprehensive overview of the results of these investigations see ref.…”