Atomic Gold Ions Clustered with Noble Gases: Helium, Neon, Argon, Krypton, and Xenon

Abstract

High-resolution mass spectra of helium droplets doped with gold and ionized by electrons reveal He${}_n$Au${}^{+}$ cluster ions. Additional doping with heavy noble gases results in NenAu+, Ar${}_n$Au${}^{+}$, Kr${}_n$Au${}^{+}$, and Xe${}_n$Au${}^{+}$ cluster ions. The high stability predicted for covalently bonded Ar${}_2$Au${}^{+}$, Kr${}_2$Au${}^{+}$, and Xe${}_2$Au${}^{+}$ is reflected in their relatively high abundance. Surprisingly, the abundance of Ne${}_2$Au${}^{+}$ which is predicted to have zero covalent bonding character and no enhanced stability features a local maximum, too. The predicted size and structure of complete solvation shells surrounding ions with essentially non-directional bonding depends primarily on the ratio $\sigma$* of the ion-ligand $versus$ the ligand-ligand distance. For Au${}^{+}$ solvated in helium and neon the ratio $\sigma$* is slightly below 1, favoring icosahedral packing in agreement with a maximum observed in the corresponding abundance distributions at $n$ = 12. He${}_n$Au${}^{+}$ appears to adopt two additional solvation shells of $I_h$ symmetry, containing 20 and 12 atoms, respectively. For Ar${}_n$Au${}^{+}$, with $\sigma$* $\approx$ 0.67, one would expect a solvation shell of octahedral symmetry, in agreement with an enhanced ion abundance at $n$ = 6. Another anomaly in the ion abundance at Ar${}_9$Au${}^{+}$ matches a local maximum in its computed dissociation energy.

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• Cold Physics and Chemistry: Collisions, Ionization and Reactions inside Helium Nanodroplets Close to Zero K
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Cited by in corpus (1)

• Solvation of Silver Ions in Noble Gases He, Ne, Ar, Kr, and Xe