The adsorption of helium atoms on small cationic gold clusters

Abstract

Adducts formed between small gold cluster cations and helium atoms are reported for the first time. These binary ions, Aun+Hem, were produced by electron ionization of helium nanodroplets doped with neutral gold clusters and were detected using mass spectrometry. For a given value of n, the distribution of ions as a function of the number of added helium atoms, m, has been recorded. Peaks with anomalously high intensities, corresponding to so-called magic number ions, are identified and interpreted in terms of the geometric structures of the underlying Aun+ ions. These features can be accounted for by planar structures for Aun+ ions with n ≤ 7, with the addition of helium having no significant effect on the structures of the underlying gold cluster ions. According to ion mobility studies and some theoretical predictions, a 3-D structure is expected for Au8+. However, the findings for Au8+ in this work are more consistent with a planar structure.

Complexes with Atomic Gold Ions: Efficient Bis-Ligand Formation

“…The experiments utilize the ultracold environment of helium nanodroplets (HND) as a nano matrix for the formation of cold, mixed complexes with gold as described in [10][11][12][13][14]16,51,63]. The experimental setup which is schematically shown in Figure 9 has been described previously in [64].…”

“…The ligand most weakly bound to gold is helium [9] and thus ligand-exchange with every other ligand can be expected inside a helium nanodroplet (HND). In the case of neutral helium droplets, this was successfully demonstrated by the growth of pristine and mixed gold clusters containing a few gold atoms [10][11][12][13][14][15][16][17][18], as well as nanoparticles and nanowires that contain many thousand atoms [19][20][21][22][23][24][25]. Recently, we doped neutral HNDs containing about 10 6 He atoms with gold vapor and investigated low-mass ions formed upon electron ionization and ejected from the massive droplets [12].…”

“…Pre-doping of charged HNDs with hydrogen was successfully utilized to prevent fragmentation of fragile molecular dopants by a gentle proton transfer reaction and avoid the exothermic charge transfer process from He n + [36,37]. Besides pristine gold cluster ions Au m + , binary cluster ions of the form He n Au m + were also observed [12,14]. For He n Au + , in excess of n = 100 helium atoms were seen.…”

Helium nanodroplets doped with copper and water

“…We are not aware of any studies of water adsorption on the copper trimer (nor trimers of other noble metals); theoretical work is needed to elucidate the origin of the apparent enhanced stability of (H 2 O) 3 Cu 3 + . [47]. Another factor in the appearance of icosahedral structure is that the size of the ion, i.e.…”

An intense source for cold cluster ions of a specific composition

“…Gold is one of our first test samples to produce clusters because, besides its immense importance for cluster science, [79][80][81] it is also a material we have a great experience with in experiments where neutral helium droplets are employed, making comparisons between the present technique and our previous apparatus most straightforward. 41,82,83 Two examples of TOF mass spectra obtained with gold as a dopant in helium droplets are shown in Fig. 7 for two different helium droplet sizes (i.e., mass-per-charge values) selected with the quadrupole bender.…”