TY - JOUR
T1 - Surface Oxidation of Supported, Size-Selected Silver Clusters
AU - Lünskens, Tobias
AU - Walenta, Constantin A.
AU - Heister, Philipp
AU - Kartouzian, Aras
AU - Heiz, Ueli
N1 - Publisher Copyright:
© 2017, Springer Science+Business Media, LLC.
PY - 2017/11/1
Y1 - 2017/11/1
N2 - 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.
AB - 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.
KW - Oxidation
KW - Second harmonic generation spectroscopy
KW - Size selected clusters
KW - Supported silver clusters
UR - http://www.scopus.com/inward/record.url?scp=85027697218&partnerID=8YFLogxK
U2 - 10.1007/s10876-017-1285-y
DO - 10.1007/s10876-017-1285-y
M3 - Article
AN - SCOPUS:85027697218
SN - 1040-7278
VL - 28
SP - 3185
EP - 3192
JO - Journal of Cluster Science
JF - Journal of Cluster Science
IS - 6
ER -