Surface Oxidation of Supported, Size-Selected Silver Clusters

Tobias Lünskens, Constantin A. Walenta, Philipp Heister, Aras Kartouzian, Ueli Heiz

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

We use surface second harmonic generation spectroscopy (s-SHG) to study the oxidation of supported, size-selected silver clusters under ultra-high vacuum conditions. The oxidation reaction of small silver clusters between Ag 9 and Ag 55 is monitored by means of their localized surface plasmon resonance. We observe a rapid decline of the SH-intensity, as soon as cluster samples are exposed to an oxygen partial pressure of 5 × 10 - 6 mbar, which is attributed to the formation of silver–oxygen-bonds. The evolution of the SH-intensity under exposure to oxygen shows a double-exponential character for all investigated cluster sizes. Since the oxidation of single crystalline silver surfaces follow single-exponential Langmuir-kinetics, the two independent pathways of SH-intensity loss are attributed to a surface- and an interface-oxidation of supported clusters, respectiveley. For small cluster sizes, a complete loss of the SH intensity is obtained, which suggests the complete oxidation of the clusters. For larger clusters a plasmonic resonance is still observed after oxidation, indicating a residual free-electron density.

Original languageEnglish
Pages (from-to)3185-3192
Number of pages8
JournalJournal of Cluster Science
Volume28
Issue number6
DOIs
StatePublished - 1 Nov 2017
Externally publishedYes

Keywords

  • Oxidation
  • Second harmonic generation spectroscopy
  • Size selected clusters
  • Supported silver clusters

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