5.1. Massenauflösung
5.4.5. Zusammenfassung der Ergebnisse für kleine Silbercluster
Abbildung 5.21.: Alle relevanten Silber-Photoelektronenspektren mit dem Verlauf der Verti-cal Detachment Energy, VDE. Die Tendenz der metallischen Bindung des Wasserstoffatoms an die Silbercluster ist erkennbar. Der Verlauf der VDE ist qualitativ gleich für die Cluster Agn−1H−(rot) und Ag−n (schwarz).
Die metallische Bindung des Wasserstoffatoms an Silbercluster konnte für den Größenbe-reich n=1−4 gezeigt werden. Der Überlapp der s-Orbitale von Silberatomen und Was-serstoffatom ergibt eine metallische Bindung. Auffällig ist der qualtitativ gleiche Verlauf der VDE für die Cluster Agn−1H und Agn in Abb. 5.21. Eine etwas größere Abweichung ergibt sich für AgH und Ag2; danach ist der Verlauf der VDE wieder homogener.
6.1. Zusammenfassung
Es konnten im Rahmen dieser Arbeit folgende Erkenntnisse gewonnen werden:
• Kupfercluster:
Für die kleinen Kupfercluster im Größenbereich n=1−4 konnte eine metallische Bindung eines einzelnen Wasserstoffatoms an den Cluster nachgewiesen werden.
Dies wurde durch den Vergleich der Photoelektronenspektren Cun, CunH und Cun+1 erreicht. Die qualitativ sehr ähnlichen Spektren von CunH, Cun+1 werden dabei als Hinweis für die metallische Bindung gedeutet. Der Verlauf der VDE für die Reihen CunH und Cun+1 ist ein weiteres Indiz für die metallische Bindung.
• Silbercluster:
Für die im gleichen Größenbereich n=1−4 untersuchten Silbercluster ergibt sich ein analoges Bild wie für Kupfer. Der Wasserstoff bindet an kleine Silbercluster metallisch, gezeigt wurde das durch den Vergleich der Photoelektronenspektren der Cluster AgnH mit denen der Cluster Agn+1. Ein Vergleich der VDE stützte die Ver-mutung der metallischen Bindung.
• Al7Hx und Al7Dx:
Die mehrfach hydrierten und deuterierten Al7H/D-Cluster wurden spektroskopiert.
Es wurde versucht die Unterschiede der isolelektronischen Spektren zu erklären, wobei sich an den an Al13 gewonnenen Erkentnisse orientiert wurde.
• Al13, Al13H und Al13D:
Die Photoelektronenspektren wurden verglichen. Die entstandenen Spektren konn-ten durch den Einfluß des Adsorbatgases auf die Clustererzeugung erklärt. Theo-retische Berechnungen der Gruppe von P. Jena tragen zur Strukturbestimmung bei.
Die Spektren entstanden in Zusammenarbeit mit der Gruppe von K. Bowen an der Johns-Hopkins- University.
6.2. Ausblick
Neben einer Erweiterung des Größenbereiches der untersuchten Münzmetallcluster bis zum Beispiel zu n=7, dem ersten Schalenabschlus, bieten sich für weitere Untersuchun-gen andere Materialien an. Ein Vergleich der Hydride der Alkalimetalle mit den reinen Clustern wäre ein interessanter Ausblick. Zum Einen gibt es nur ionische Verbindungen der Alkalihydride, zum Anderen würden die Ergebnisse weiteren Aufschluss über das Ver-halten einfacher Metallhydride geben.
Artikel
• Grubisic, A.; Li, X.; Stokes, S. T.; Vetter, K.; Gantefor, G. F.; Bowen, K. H.; Jena, P.; Kiran, B.; Burgert, R. & Schnockel, H.
Al13H−: Hydrogen atom site selectivity and the shell model The Journal of Chemical Physics 131, 121103 (2009)
Poster
• Dietsche, R.; Lim, D.C.; Bubek, M.; Ketterer, T.; Vetter, K.; Kim, Y.D. & Ganteför, G.
Oxidation / Reduction of Aun(n=2−13) Clusters on SiO2/ Si on HOPG Trends in Nanoscience, Kloster Irsee, 24-28 Februar 2007
• Fischer, T.; Götz, M.; Cordes, J.; Vetter, K. & Ganteför G.
New setup for photoelectron spectroscopy of mass selected clusters. high mass range and resolution, high photon energy and high energy resolution S3C-Symposium on Size-Selected Clusters Brand, Österreich, 12-16 März 2007
• Dietsche, R.; Lim, D.C.; Bubek, M.; Ketterer, T.; Vetter, K.; Kim, Y.D. & Ganteför, G.
Oxidation / Reduction of Aun(n=2−13) Clusters on SiO2/ Si on HOPG S3C-Symposium on Size-Selected Clusters Brand, Österreich, 12-16 März 2007
• Vetter, K.; Cordes, J. & Ganteför G.; Li, X.; Grubisic, A.; Stokes, S.T. & Bowen K.
Unexpected isotopic effect on AlnHm−-Clusters
Clustertreffen 2007, Berlin-Spandau, 23-27 September 2007
• Dietsche, R.; Lim, D.C.; Bubek, M.; Ketterer, T.; Vetter, K.; Kim, Y.D. & Ganteför,
G.
Oxidation / Reduction of Aun(n=2−13) Clusters on SiO2/ Si on HOPG Clustertreffen 2007, Berlin-Spandau, 23-27 September 2007
• Vetter, K. & Ganteför G.; Li, X.; Grubisic, A.; Stokes, S.T. & Bowen K.
Unexpected isotopic effect on Al13H−-Clusters
S3C-Symposium on Size-Selected Clusters Brand, Österreich, 9-13 März 2007
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