Electronic and vibrational signatures of the Au102(p -MBA) 44 cluster

Eero Hulkko, Olga Lopez-Acevedo, Jaakko Koivisto, Yael Levi-Kalisman, Roger D. Kornberg, Mika Pettersson*, Hannu Häkkinen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

81 Scopus citations


Optical absorption of a gold nanocluster of 102 Au atoms protected by 44 para-mercaptobenzoic acid (p-MBA) ligands is measured in the range of 0.05-6.2 eV (mid-IR to UV) by a combination of several techniques for purified samples in solid and solution phases. The results are compared to calculations for a model cluster Au102(SMe)44 based on the time-dependent density functional theory in the linear-response regime and using the known structure of Au102(p-MBA)44. The measured and calculated molar absorption coefficients in the NIR-vis region are comparable, within a factor of 2, in the absolute scale. Several characteristic features are observed in the absorption in the range of 1.5-3.5 eV. The onset of the electronic transitions in the mid-IR region is experimentally observed at 0.45 ± 0.05 eV which compares well with the lowest calculated transition at 0.55 eV. Vibrations in the ligand layer give rise to fingerprint IR features below the onset of low-energy metal-to-metal electronic transitions. Partial exchange of the p-MBA ligand to glutathione does not affect the onset of the electronic transitions, which indicates that the metal core of the cluster is not affected by the ligand exchange. The full spectroscopic characterization of the Au102(p- MBA)44 reported here for the first time gives benchmarks for further studies of manipulation and functionalization of this nanocluster to various applications.

Original languageAmerican English
Pages (from-to)3752-3755
Number of pages4
JournalJournal of the American Chemical Society
Issue number11
StatePublished - 23 Mar 2011
Externally publishedYes


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