| Autor: |
Lünskens, Tobias, Walenta, Constantin, Heister, Philipp, Kartouzian, Aras, Heiz, Ueli |
| Předmět: |
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| Zdroj: |
Journal of Cluster Science; Nov2017, Vol. 28 Issue 6, p3185-3192, 8p |
| Abstrakt: |
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 $$\hbox {Ag}_{9}$$ and $$\hbox {Ag}_{55}$$ 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 $$5 \times 10^{-6}$$ 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. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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