Spectroscopy of gold atoms and gold oligomers in helium nanodroplets

Publikation: Beitrag in einer FachzeitschriftArtikelForschungBegutachtung

Abstract

The 6p 2P1/2 ← 6s 2S1/2 and 6p 2P3/2 ← 6s 2S1/2 transitions (D lines) of gold atoms embedded in superfluid helium nanodroplets have been investigated using resonant two-photon ionization spectroscopy. Both transitions are strongly blue-shifted and broadened due to the repulsive interaction between the Au valence electron and the surrounding helium. The in-droplet D lines are superimposed by the spectral signature of Au atoms relaxed into the metastable 2D states. These features are narrower than the in-droplet D lines and exhibit sharp rising edges that coincide with bare atom transitions. It is concluded that they originate from metastable 2D state AuHen exciplexes that have been ejected from the helium droplets during a relaxation process. Interestingly, the mechanism that leads to the formation of these complexes is suppressed for very large helium droplets consisting of about 2 × 106 He atoms, corresponding to a droplet diameter on the order of 50 nm. The assignment of the observed spectral features is supported by ab initio calculations employing a multiconfigurational self-consistent field method and a multi-reference configuration interaction calculation. For large helium droplets doped with Au oligomers, excitation spectra for mass channels corresponding to Aun with n = 2, 3, 4, 5, 7, and 9 are presented. The mass spectrum reveals even-odd oscillations in the number of Au atoms that constitute the oligomer, which is characteristic for coinage metal clusters. Resonances are observed close by the in-droplet D1 and D2 transitions, and the corresponding peak forms are very similar for different oligomer sizes.

Originalspracheenglisch
Aufsatznummer024305
FachzeitschriftJournal of Chemical Physics
Jahrgang149
Ausgabenummer2
DOIs
PublikationsstatusVeröffentlicht - 14 Jul 2018

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Helium
oligomers
Oligomers
Gold
D lines
helium
Spectroscopy
gold
Atoms
spectroscopy
atoms
metastable state
spectral signatures
Coinage
metal clusters
Superfluid helium
mass spectra
configuration interaction
self consistent fields
Relaxation processes

ASJC Scopus subject areas

  • !!Physics and Astronomy(all)
  • !!Physical and Theoretical Chemistry

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Spectroscopy of gold atoms and gold oligomers in helium nanodroplets. / Messner, Roman; Schiffmann, Alexander; Pototschnig, Johann V.; Lasserus, Maximilian; Schnedlitz, Martin; Lackner, Florian; Ernst, Wolfgang E.

in: Journal of Chemical Physics, Jahrgang 149, Nr. 2, 024305, 14.07.2018.

Publikation: Beitrag in einer FachzeitschriftArtikelForschungBegutachtung

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AU - Ernst, Wolfgang E.

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